Publicaciones Geolo_gicas Especiales Del lngeominas

Publicaciones
Geolo_gicas
Especiales
Del
lngeomina s
No.2,pp. 1-186,1979
Bogota - Colombia
ISSN- 0120- 078X
By
FERNANDO ETA YO-SERNA
UNIVERSIDAD NACIONAL DE COLOMBIA
ISSN . 0120. 078X
Publ. Geol. Esp.
Ingeominas

PRESENTACION
Podni parecerles extrafio a los lectores que se publique en Colombia un tra­
bajo en ingles. Esta decision del Comite de Publicaciones del INGEOMINAS responde a
consideraciones puramente practicas. Efectivamente, traducir un trabajo tan extenso
como el del profesor Fernando Etayo significa un esfuerzo enorme; por otra parte, su
nivel y su especializacion lo destinan fundamentalmente a ser leido por profesionales
de Ia geologia. "··
Gustenos o no, el ir.gles se ha vuelto el idioma del intercambio cientifico,
una especie de latin del siglo XX. Todo profesional de las Ciencias de Ia Tierra -y me
atreverfa a decir, de las otras Ciencias-· que no quiera permanecer aislado de los ultimos
avances en su campo debe absorber mensualmente varias decenas de articulos especiali­
zados.
La inmensa mayorfa de esta produccion, que a muchos les parece desmedida,
es publicada en ingles.
De manera que a menos de contentarse con traducciones de textos que ge­
neralmente tienen varios afios de retraso o con trabajos sabre temas locales publicados
en su propio idioma, todo ge6logo que intente mantenerse razonablemente informado
debe leer en ingles.
INGEOMINAS tiene como una de sus funciones mas importantes el difundir·
los conocimientos que existan acerca de la Geologia de Colombia. En esta oportunidad,
el Instituto presenta a la comunidad geologica el excelente trabajo del profesor Fernan­
do Etayo, realizado para optar el titulo de PhD. en la Universidad de California de
Berkeley. No quiero caer en Ia academica costumbre, tan difundida en nuestro media,
de lanzarme en un elogio rimbombante de mi buen amigo Fernando; ofenderia ademas
su tradicional modestia. Sin embargo es buena que los gedlogos colombianos·sepan que
en este momenta Fernando, gracias al Convenio celebrado entre Ia Universidad Nacio­
nal y el INGEOMINAS, esta desarrollando con ge6logos de esta ultima entidad y estu­
diantes de la primera una intensa labor de corr elacion estratigrruica de las rocas crta­
ceas de la Cordillera Oriental, cuya programacion inicial es de dos ailos.
colombiana.
Estoy convencido del gran avance que significara este trabajo para la geologia
Este Instituto se ha propuesto publicar en forma sistematica todos los traba­
jos ineditos acerca de la geolog!a en nuestro pais. Esta en imprenta la tesis de doctora­
do de Daria Barrera y seguiran, en esta colecci6n de Publicaciones Geologicas Especia­
les, otras contribuciones ineditas tanto de colombianos como de extranjeros, en espa-
. fi.ol y en ingles. Espero que los estudiosos de la geologia colombiana no vean en este
esfuerzo un intento extranjerizante sino una clara decision de robustecer el desarrollo
de las Ciencias de la Tierra en Colombia.
Junia de 1979
Michel Hermelin

PUBLICACIONES GEOLOGICAS ESPECIALES DEL
""
INGEOMINAS
ZONATION OF THE
CRETACEOUS OF CENTRAL
COLOMBIA BY AMMONITES
By
FERNANDO ETA YO-SERNA
UNIVERSIDAD NACIONAL DE COLOMBIA
(Departamento de Geociencias, e I.C.N.M.H.N.)
MINISTERIO DE MINAS Y ENERGIA
INSTITUTO NACIONAL DE INVESTIGACIONES GEOLOGICO·MINERAS
1979
Bogota-Colombia, No, 2, pp, 1·188 ISSN • 0120 · 078X

Precio de cada ejemplar: $ 300.00
7.50
Publicacion no periodica
us $
Fonnato de Publicacion: 21.5 x 27.5 em
Derechos Reservados por:
INGEOMINAS: lnstituto Nacional de Investigaciones Geologico- Mineras
Carrera 30 No. 51-59
Apartado Aereo No. 4865 ·Bogota- Colombia
All the concepts emitted in this publication are of the entire responsability of the author.
Edited and printed by Ingeominas.

CONTENTS
ABSTRACT . . . . .. . . . · . . • • . • • . . . . . . • . . . . • . . . . . . . . • • . . . . • • • • . . . . • • , 1
.
INTRODUCTION .
CKNOWLE GMENTS-
. • . . . . . . . . • . : • • • . • . . . . . . • . • • . . . . • . . . . • . . . ,_:-i.c:}._ .
.
• • • •
.
.. .
A D • • . . • • • • ; ,
....
:-- . ' -ri'::j.!.:_
. -
. . • • • • • • . • . . • - . • . . • • • • . • . • - . .-; t•·, -.- • • •
Page
PHYSICAL STRATIGRAPHY • . . . • '" ' . • • • • • . . . • . • • . . • . • . . • • . • . • ,.• .,"ii.... 4
I. THE CRETACE OUS SECTION FROM VILLA DE LEIVA TO LOMA PIEDRA
GORDA, LA RGELY FROM ETAYQ-SERNA,1972. . . . . . . . . . . . . . . . . 4
PAJA FORMATION . . . . . • • , . . . . . . . . . • . . . . • , • . • : . .. . .. . ... . . . 4
SAN GIL GROUP . . . . . . . • . - . • . . . . . . . . . . . . . . . . . . . . . . • . .
2
3
. . . .. . . . 4
CHURUVITA GROUP • . . . . . . ·- · . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
CHURUVITA FORMATION . . . . . . • . . • . . . . , . . • . . . • , . • . , ....... ,. 7
SAN RAFAEL FORMATION . . . . • .. . • • • . . . . .. . . • . • .. • . . .. . . •. • ,.. 7
CONEJO FORMATION . . . . . . . . . . . . . . • . . . . • . ; .......... , .. , . . . 7
PLAENERS FORMATION . • • . . . . . .. . . • . ,. . . ...... . ..... . . .... . 8
GUADALUPE FORMATION . . , . . . . . . . . . . . . . . . . . . . . . . . . . • . . . • . . 8
II. THE CRETACEOUS SECTION IN THE APULO, VIOTA, LAS MESITAS REGION 8
LA NA VETA FORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , , . . 8
VILLETA GROUP . . . . . . . . . . • . . . . • . . . . . . • . . . . . . . . • . . . . . • . . . . 8
SOCOT A MEMBER . . . . . . . . . . . . . . . . . . . . . . • • . • . . . . . . . . , , . . . . . . 9
CAPOTES MEMBER • , . . . . , • . . • . . . . , . . . . . . . . . . . . . . . . . . . . • . . . . 10
HILO FORMATION • . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . . • • . . 11
LA FRONTERA FORMATION. . . . . . . . . • . . • . . . . . . . . • . . . . . . . . . . . . 11
COMMENTS . . . . . . . . . • . . . . . • . . . . . . . . . . . • . . . . . . . . . . . . . . . . . • 11
BIOSTRATIGRAPHY . . . . . • . . . . . . . . . • • . . . . . . • . . . . . . . • . . . . . . . • . .
ASSEMBLAGE ZONES PROPOSED FOR USE IN COLOMBIA. . • . . . . . . • . .
. . . . 13
. 13
Du{renoyia sanctorum-Stoyanowiceras tre{{ryanus Assemblagezone
........................................ 13
Parahoplites (?) hubachi- Acanthohoplites (?) /eptocerati{orme
Assemblage-zone . . . . . . . . . . . . . . . . . . . . . . . . . . . • . . . . 13
Douvilleiceras solitae-Neodeshayesites co/umbianus Assemblagezone........................................
14
Platiknemiceras co/ombiana-Rinconiceras rinconi-Lyelliceras
pseudolyelli{orme Assemblage-zone . . . . . . . . . . . . . . . . . • • 14
Mammites nodosoidesappelatus-Franciscoites suarezi Assemblage-zone
. • . . . . . • • . . . . • . . . • , . . • . . . . . . . • . . . . . . . . 14
G/oriaceras correai-Protexanites cucaitaense - Codazziceras
scheibei Assemblage-zone ...... : . . . • . • . . . . . . . . . . . . • 15
Lenticeras baltai-Paralenticeras sieversi Assemblage-zone. . . . . .
TABLE I................................................. 16
·i-
· · 15

Page
SYSTEMATIC DESCRIPTIONS • • . • • • • . . . . . . • . • • . . • . • • . • • . . • . . · · • · • . • . • 17
Order AMMONOIDEA . . . . . . . . . • . . . . . . . • . . . . . . . . . . . . . . . . . . • . • 17
Family PHYLLOCERATIDAE. . . . . . . . . • • . . . . . . . • . . • . . . . . • . . . • . . . 17
Family GAUDRYCERATIDAE.................................. 19
Family ANCYLOCERATIDAE .................................. 20
Family PTYCHOCERATIDAE................................... 21
Family ACONECERATIDAE . . . . • . . • . . . . . . . . • . . . . . . . . • . . • . . • • . . 22
Family DESMOCERATIDAE . . . . . . . . . • . . . . . . . . . . . . • . . . . . . . . . . . . 23
Family P ACHYDISCIDAE . . . . . . • . . • . . • . . . . . • . . . . . • . . • . . • • . • . . . 30
Family TROCHLEICERATIDAE. . . • . . • . . • • . • . . . . . . . . . . . . . . • • • . . . 31
Family DOUVILLEICERATIDAE. . . . . . . . . . . . . • . . . . . . . . . . • • . . . . . . 32
Family DESHA YESITIDAE . . . . . . • . • . . . . . • . . • • . . . . . . . . . . . . . • . . . 58
Subfamily PARAHOPLITINAE............. . . . . . . . . • . . . . . . . . . . . • 72
Family ENGONOCERATIDAE . . . . . . . . . . • . . • . . . . . . . . . . . • . . . . . • . 74
Family BRANCOCERATIDAE ......... . . . . . . . • . . . . . • • . . . . • . . . . . 78
Family LYELLICERATIDAE . . . . . . . . . . . . . • . . . . . . . . . : ... ... . . . .. 79
Family ACANTHOCERATIDAE ................................. 83
Family MAMMITIDAE. . . • . . . . . . . . . . . . . . : . . . . . . • • • . . . . . . . . . . . . 85
Family VASCOCERATIDAE. . . • . . . . • . . • . . . . . . . . . . . . . . . . . . . . . . . . 87
Family COILOPOCERATIDAE.................................. 90
Family COLLIGNONICERATIDAE. . . . . . . . • . . . • . . . . . . . . . . . . . . . . . . 92
Order NAUTILIDA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Family CYMATOCERATIDAE................ .................. 104
SUMMARY . . . . . . . . . . . . . • . . . . . • • . . . . . . . . . • . . . • . . . . . . • . . . . • • . • • . . 105
RESUMEN • • • . • . . . . . • • . • • . . • . • • . • . • • • • . . • . . • • • . . . ; • . • . . . . . . . • . . • 106
RESUME. .. ... . . .. ...... . . . ... ..... .. . ... ...... ...... .. .... ... . 107
RIASSUNTO • . . . • . . . • • . • . . . . • . . . . • . . . . . • . . • . • . . • • . • • . • . . • . . . . • • . 108
ZUS.AIDIENF ASSUNG . . . . . . • . . • . . . . . . • . . . • . . • . . • . . . . . • . . • • • . . . . . . . 109
REFERENCES.... .. .... .... . . . ...... ... ...... ... ... .. ... . . . ...... 110
'INDEX OF GENERA AND SPECIES. • . . • . • . . • . • • . • • . • . . . . . . . . . . • . . . . • • . • 182
ILLUSTRATIONS
Text-Fig. 1. Map of Colombia showing location of sections investigated in detail • • . . 5
Text-Fig. 2. Composite columnar sections Villa de Leiva · Apulo. • . • • . . . • • . . . . . 6
Text-Figs;--·3 • 9. Sutures and whorl sections of the studied ammonites . . . . . • • . . . . • . . 12C
Text-Figs. 10·17. Scattem diagrams of some of the studied ammonites . • . . . . . . . . . . . .
Plate 1.
Plate 2.
Plate 3.
Ammonites from the Dufrenoyia sanctorum·Stoyanowiceras treffryanus
Assemblage zone. Figs. 1-8. Upper Aptian.
Ammonites from the Du(renoyia sanctorum-Stoyanowiceras tre(fryanus
·
Assemblage zone . Figs. 1-10. Upper Aptian.
Ammonites from the Dufrenoyitz sanctorum-Stoyanowiceras treffryanus
Assemblage zone. Figs.1-2, 4-8, 10·13. Ammonites from the Parahoplites
('?) hubachi-Acanthohoplites ('?) leptocerati(orme Assemblage zone. Figs.
3, 9. Upper Aptian. --
.-11·
13
15:
15

Pl ate 4.
Plate 6.
Plate 6.
Plate 7.
Plate 8.
Plate 9.
Plate 10.
Plate 11.
Plate 12.
Plate 13.
Plate 14.
Plate 15.
Ammo nites fro m the Du(renoyia sanctorum-Stoyanowiceras treffryanus.
As semblage zo ne. Figs. 1- 3, 5, 7- 8. Ammo nites fro m the Prahoplites (?)
hubachi-Acanthohoplites (?) Jeptocerati(orme Asse mblage zo ne . Figs .
4, 6. Uppe r Apt ian. . . . . . . . . . • . . . . . . . . . . . . . . . . . . . • . . . . . . 158
Ammo nites fro m the Du(renoyia sanctorum-Stoyanowiceras tre(fryanus
Assel!l blage zo ne . Fi gs. 3, 9. Ammo nites fro m the Parahoplfte11 (?) hubachi·Acanthohoplites
(?) leptocerati(orme Asse mblage zo ne . l'' igs. 1- 2, 4- 8.
Uppe r Ap tian . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
Ammo nite s from the Dufenoyia sanctorum-Stoyanowiceras treffryanus
Asse mblage zone. Fi gs. 1- 20. Upper Ap ti an • . . . . . . . . . . . . . . . . . . . 162
Ammo nites fro m the Du(renoyia sanctorum-Stoyanowiceras tre{fryanus
As se mblage zone. Fi g. 9. Ammo nite s fro m the Parahoplites (?) hubachi­
Acanthohoplites (?) leptocerati{orme Asse mblage zo ne . Figs; 1- 4, 8.
Uppe r Ap tian. Ammonites fro m the Douvilleiceras solitae-Neodeshayesites
columbianus Assemblage zo ne . Fi gs. 5-7 . Lo wer Albian • . . . . . . . 164
Ammo nite s fro m the Douvilleiceras solitae-Neodeshayesites columbianus
As se mbl age zone . Fi gs. 1-7 . Lo wer Albian .. . • . . . . . . . • . . . . . . . . . . 16.6
Ammo ni tes fro m the Douvilleiceras solitae-Neodeshayesites columbianus
Asse mbl age zo ne . Fi gs. 1- 3, 7- 8. Lo we r Al bian . Ammonites fro m the Platiknemiceras
colombiana-Rinconiceras rinconi-Lyelliceras pseudolyelli-
{orme Asse mblage zone . Fi gs. 4-6 . M idd le Albian .. . . . . . . . . . . . . . . . , ·. · 168
Ammonite s fro m the Parahoplites (?) hubachi-Acanthohoplites (?) leptocerati{orme
Assembl age zo ne . Fi gs . 2- 3. Uppe r Aptian . Ammo nites fro m
the Douvilleiceras so/itae-Neodeshayesites columbianus Asse mbl age zo ne .
Fi gs. 1, 3- 10 . Lo wer Al bian . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Ammo nite s fro m· the Platiknemiceras colombiana-Rinconiceras rinconi-
Lyelliceras pseudo/yelli{orme Assemblage zone. Fi gs. 1-9. Midd le Alb ian .
Ammonites fr om the Plaliknemiceras colombiana-Rinconiceras rinconi-
Lyelliceras pseudolyelli{orme As se mblage zone . Figs. 1· 4. Midd le Al bi an . 174
Ammonite s fro m the Mammites nodosoidesappelatus-Franciscoites suarezi
As se mblage zone . Figs. 1-11, 13-15. Lo we r Turon ian . Ammonites
from the Gloriaceras correai-Protexanites cucaitaense-Codazziceras scheibei
Asse mbl age zo ne. Figs. 12, 16- 19. Lo wer Con iacian . . . . . . . . . . . . 176
Ammoni te s from theMammites nodosoidesappelatus-Franciscoites suarezi
Asse mblage zo ne . Fi g. 5. Lo wer Tu ro nian. Ammonite s fro m the Gloriaceras
correai-Prolexanites cucaitaense·Codazziceras scheibei Asse mblage
zo ne. Fi gs. 1- 4, 7- 10.Lower Co ni aci an . . . . . . . . . . . . . . . . . . . . . . . . 17 8
Ammon ite s fr om the Gloriaccrus correai-Protexanites cucaitaense-Codazziceras
scheibei As se mblage zone. Fi gs 1- 4. Lo wer Co niacian. . . . . . . 180
* * *
17 0
17 2

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMtlNITES 1
Cretaceous rocks ranging in age from
. Upper Aptian to Lower Santonian llve been
carefully mapped, measured and colleoted bed
by bed in two regions (it Central Colombia namely_:
Villa de Leiva (Department Boyaca) and
Apulo (formerly Rafael Reyes, Department
·
Cundinamarca).
The first mentioned sequence comprises
about 2.000m of locally highly fossiliferous
shales, although limestones, sandstones and
chert beds are interspersed and sporadically
yielded fossils. At Apulo the sequence consists
dominantly of shales with locally abundant
fossiliferous calcareous "concretions" and one
intercalcation of fossiliferous graded-beddedsandstones
(turbidites) with a total thickness of
about l.OOOm.
The lithostratigraphic terminology utilized
is that previously proposed and published by
the writer, the old terminology is reevaluated
and some new units are introduced and their
type sections and reference sections described.
Similarly the occurrence of ammonites is indicated.
The core of the investigation is however
the study and description of ammonite taxa:
102 species assigned to 52 genera were thoroughly
investigated, of them 85% of the species
and 21% of the genera are considered to represent
new taxa. A zonal scheme consisting of
7"A'iSemblage zones" is proposed, based on the
succession of ammonites in these two sections,
hopefully it will be a yardstick for the Cretaceous
biostratigraphy of the· northern part of
South America. No close correspondence between
lithostratigraphic boundaries and bios-
Caminante no hay camino ,
se hace camino a/ andar.
ABSTRACT
* * *
Yo u ask me the secret
It only has a word,again.
tratigraphic units has been found, however
some taxa of ammonites witeculiar morphologic
characteristics seem to-'associated with
definite lithofacies.
The diverse taxa of ammonites were studied
through dissection of their conchs in order
to determine their ontogenetic changes and all
morphological characteristics were evaluated in
an attempt to understand each taxon independently.
From the taxonomic investigations and
the known stratigraphical distribution of the
faunas it is shown once more that similar--although
not 'identical' -morphologic types of
ammonites recurred during Cretaceous times.
The taxonomy resulting from· the-criteria
utilized herein indicate that the described taxa
have proportionally a distinctly South American
character, however some ubiquitous elements,
several of them previously unknown from the
Cretaceous of South America are recorded; as a
possible biological explanation for this fact it is
hypothesized, that as in the case of modem cephalopods
the ubiquitous elements of the ammonoid
faunas may correspond to those hatched
from small eggs (with small protoconchs) and
vice versa.
All the species described are illustrated by
drawings of their whorl cross-section and suture
line, and at least one photograph of each.
Conch measurements are expressed in
mm. The symbol D represents the diameter
of a volution. Euw is the external umbilical
width. H is the maximum height and W the
maximum width of the whorl.
Me habeis preguntado que hila el
crustacea entre sus patas de oro
y os re spondo: e/ mar lo sabe.
(MACHADO, HOLUB, NERUDA, poets)
But all this is unripe fruit. Our scholars will some day know more than their masters do
now; so let us patiently continue our work and rema in friends.
E. Suess.

2 F. ETA YO· SERNA
The materials that constitute the core of
this study have been worked on through several
years. Originally Professors J. de Porta and M.
Julivert suggested I undertake the summarization,
according to lithologic units, of the
faunas recorded in any way from the Creta·
ceous of Colombia.
At the end of the original investigation it
was apparent that if progress was to be made in
the biostratigraphy of the Cretaceous in Colom·
bia, it had to be started {rom the beginning,
that is to say through the detailed geologic
mapping of the key areas, the building up of columnar
sections, the collecting bed by bed of
the fossiliferous units, the monographic treatment
of the faunas recovered and the proposal
of zonal schemes based on the information obtained
during the field work. I have attempted
to do that and I hope that I have not contributed
additional complications to the task.
It is obvious that a work of this nature
necessarily had to pass through several pauses
and obstacles, however cooperation was always
found, willingly and uncompromisingly from
the people in charge of the geological institutions
of Colombia.
I have collected fossils largely from two
rions where I have mapped in detail mySirf,
or have had the valuable cooperation of other
field geologists; the areas investigated in the stratigraphical
researches have been more extensive
than those studied in detail. Two regions were
selected as initial key areas, both are classical in
the geological literature of Colombia: .Jijljp_.de
L_!fY.Jl (Department Boyaca) and /wJJ]o (formerly
called Rafael Reyes; Department Cundinamarca).
I have limited my study to beds and
fossils in the interval Upper Aptian to Lower
Santonian; two reasons have influenced my decision:
many classical fossils in the paleontological
literature of Colombia presumably had come
from beds of these ages, and second the
opening of new roads offered the possil-,ility of
exploring fresh, undisturbed outcrops. As a rule,
fossils not found in situ, or impressions only
were not collected in the early phase of the
study.
Two hypotheses arrived at as a result of
this study I think worth emphasizing: A) It has
been common to find con ere lions or lens-like
calcareous ·bodies paved with ammonites, fish
remains, bivalves and gastropods. This has occurred
in different types of host rock: clay-shale,
graded sandstones, etc. (Rod and Mayne, 1954,
p. _207; f:JJO'O·Serna, 1968). _It is suggested in
th1s repdrt . . _t6pt these "bod1es" represent the
result "ote'chanical 'concentration, by the
action of submarine currents on organic remains ·
with similar hydrodynamic behavior; in other
words these "bodies" may represent "microchannels"
and their fossiliferous content may
I. IN TRODUC TION
include both morphologically different or morphologically
similar groups that by a simple
statistical analysis could be treated as a single
taxon. I surmise also cephalopods had definite
niches in their communities. B) The distribution
of cephalopods may be considered mainly
{rom two different points of view: a) necroplanktonic,
2) planktonic; the first approach
does not have any bearing on the origin and
development of new groups or the establishment
of new communities of cephalopods in
areas newly invaded by the sea.
A biological reference point to keep in
mind is that most living mollusks attain their
distribution largely by the possession of at least
one life stage capable of active dispersal or to
passive transportation. The latter type of
dispersal is usually accomplished during the
larval stage, and the larval stage resulting from
development from eggs poor in yolk usually has
a long planktonic stage (Thorson, Scheltema,
Ockelman). This seems valid not only for
mollusks with a larval stage but for recent
cephalopods with a direct development (Vokes
in Lane, 1960, p. 127).
Druschitz and Khiami (1970, p. 36) have
called this early ontogenic stage in fossil cephalopods
ammonite lla. I agree with their idea that
probably the)' did not behave differently from
thir modern relatives in mode of reproduction.
Recent Nautilu s hatches from large eggs sacs.
(Willey, 1896, 1902) and its intraegg development
lasts long enough to produce large ''n autiloide
lla (?)" [see Stenzel, 1964, K82], but as
noted by Willey (1896, p. 222) from observing
the protoconchs of ammonites, could not some
of them have hatched from eggs poor in yolk
with a corresponding ability {or long lasting
planktonic transportation?.
Some groups of ammonoids could have
been distributed by currents in their ammon ite
lla stage. In consequence endemic morphologic
types of cephalopods could be associated
with those "transoceanic travelers", with the
latter making intercontinental correlation
feasible, while the former groups may be useful
for establishing local biostratigraphical sequences.
In consequence I do not find it necessary or even
practical to invoke a ubiquitous nature {or
many of ammonite genera. Convergent iterative
groups have repeatedly been shown among
ammonoids. Consequently I feel that the
necroplanktonic distribution of fossil cephalo·
pods has its special role in intrabasinal distribution
of fossil cephalopods but the life dispersal
o. ( them occurs during the arnmonitella stage.
· - All the material studied in this report will
be housed as the basic type collection of the Ins·
titulo de Ciencias Naturales Museo de Historia
Natural of the Uhiversidad Nacional de Colombia,
Bogota (U.N.C.M.H.N.C.P. No.).

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 3
Many thanks to Professors J. de Porta and
M. Julivert for their valuable suggestion and al·
ways encouraging example. I also want to thank
Professor Robert Hoffstetter who called to my
attention the importanc..of attending afoteign
Institution for advanced studies; to Dr. Jesus A.
Bueno [former Thechnical Director of the Mi·
nisterio de Minas y Petroleos of Colombia), to
Dr. Andres Jimeno rformer Director of the
Geological Survery o{ Colombia 1 who gave me
their support from the beginning of this investigation;
to Dr. Ramiro Lobo [Chief of the Conservation
Branch of the Ministerio de Minas y
Petroleos of Colombia 1 for his cooperation in
obtaining a loan for my graduate studies at
Berkeley.
I have to thank the Universidad Nacional
de Colombia, the Institute de Especializaci6n
Tecnica en el Extranjero (ICETEX) and the
Scholarship Division of the Organization of the
American States (OEA) for their economic sup·
port to complete my researches. Financial sup·
port for the plates included herein was provided
by the Fondo Colombiano de Investigaciones
Cientfficas y Proyectos Especiales "Francisco
Jose de Caldas" (COLCIENCIAS).
I have to acknowledge Professors W.B.N.
Berry, D.A. Savage, J. T. Gregory, C.M. Gilbert,
for their willingness to be member of my com·
mittee; thanks are also due to Dr. Ralph W.
Imlay and again to Professor Charles M. Gilbert
for their willingness to serve on my thesis .committee.
Many friends have shared with me their
ideas and also their skill in field work, of them
G. Renzoni, D. Barrero and C. Caceres-Giron
should not be blamed for my errors. Several
friendly field aides, Messrs. C. Giraldo, H.
Peiia, A. Aleman, J. Higuera, J. Duarte, had to
bear with my stubborn insistency to work
under changing weather conditions or had to
carry the heavy load of unprepared fossils. L. F.
Peii.a, and J. Garzon were very useful in helping
with the preparation of the fossils, I
thank them also.
ll.ACKNOWLEDGMENTS
The following institutions are acknowledged
for their gracious loan of specimens for
comparison: Museum of Paleontology, University
of California, Berkeley [Mr. J. Peck, Jr.],
Museo Geologico, lnstituto Nacional de Investigaciones
Geologico Mineras, Bogota, Colombia
rProf. L. F. Rincon and former Director Dr.
A. Alvarez]; the University of Michigan, the
Texas Christian University and the Academy of
Natural Sciences of Philadelphia; the British Mu·
seum (Natural History). Dr. J. Helms of the
Humboldt • Universitat in Berlin, DDR; provi·
ded me with excellent photographs of H. Karsten's
original material.
I have to acknowledge two old classmates
of mine, deceased Geologist Pedro Carvajal,and
Geol. Dip!. Ruben D. Llimis, who unafraid
backed with their wealth my loan from
ICETEX; Mrs. Amparo Prada was most helpful
in my dealing with the OEA.
Many thanks to Mrs. Gloria C. de Campos
and Mrs. Ines E. de Torres, who did the compo·
sing operation of the final version of the
manuscript. I thank Mr. Carlos Ruiz for his
assistance in improving the quality of the
text-figures.
The author could not have published this
paper had it not been for the compelling interest
of Dr. Alberto Sarmiento-Alarcon, and
especially Dr. Michel Hermelin, Director
Institute Nacional de Investigaciones Geologico
Mineras (INGEOli;JINAS).
I have a deep debt to Professor J. W. Durham
for his highly valuable scientific advise, his
thoughtful interest and his thoroughly under·
standing of my purposes during my studies at
Berkely.
In no way I am holding anybody except
myself, for any heresy I may have fallen into.
I hope this study, as simple as I see it, to
be acceptable to my family, my teachers, my
friends and to those who preceded me in the
study of the Cretaceous of Colombia. If this
work is found to be useful to my own country,
then I will be really pleased.

4 F. ETA YO· SERNA
PHYSICAL STRATIGRAPHY
In the present report only those units
dealt with or that have yielded fossils conside·
red in the investigation will be discussed. A mo·
re extensive discussion will be found in Etayo
Serna (1968a, 1968b), Julivert (1968) and Ca·
ceres and Etayo-Serna (1969). The location of.
the two areas studied in detail is shown on Text
Fig. 1.
,... .._ _
--:-\.YTHE CF;_TA_OUS SECTION_!:ROM
VILLA DE LEIVA TO LOMA PIEDRA
. GORDA. LARGELY_FII,OM .'J'AYQ
SERNA, 1972, SEE TEXT FIG. 2A
PAJA FORMATION
(LoweFHauieriViafi"-Upper-Aptian pars)
The fonnation is typically exposed on the
north bank of Quebrada La Paja where it enters
the Rio Sogamoso (Middle Magdalena Valley),
and was nrst described by 0. c. Wheeler
(Morales et al., 1958). The Paja Fonnation crops
out extensively at Villa de Leiva and surrounding
areas. In addition, it is exposed in a broad
band east of the Arcabuco Anticline. Morpho
logically it forms hills, some of which are being
mined for gypsum. Essentially, the Paja is a thick
sequence of black to variegated shales with abundant
calcareous concretions. Frequent intercalations
of gypsum and thin beds of argillaceous
limestone are also present.
The formation can be divided in three
units: (a) a !erpE _of blak clay she which
weather to a reodJSli color, w1th sandy mterbeds
which represent the feather edge of a thick sandstone
body observed at this S8llle horizon to the
northeast of Villa de Leiva; (b) 8J!1J4_1e_

•
A) VILLA DE LEIVA
-
B) APULO
-
so
t: A
s
'G 100
.0

FIGLH 1\ 2
2AJ Vl:LLA DE LEIVA
CD
-:i
·;;
0
" 0
"' t
"-
s. 1:20;000
'-"-' -'-"-'-'='1
·
· :

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES
CHURUVITA GROUP
(Upper Albian ? pars-Turonia!" pars?)
The name "Churuvita Group" was first
proposed by Etayo Serna (1968b), with the type
locality a section on Quebrada Churuvita (a
tributary of Rio Samaci) along the Sachica­
Puente Samac& highway; According to Etayo
Serna, the Churuvita Group is comprised of the
Churuvita Fonnation and the overlying San Rafael
Fonnation.
The Churuvita Fonnation was originally
described by Etayo Serna (1968a) who selected
as the type locality the exposures on Quebrada
Churuvita along the Sachica-Puente Samaca
road. In the area of interest, the Churuvita Formation
forma the highest ridge on the west
flank of the Arcabuco anticlinorium; it is also
exposed on the limbs of the Churuvita syncline
along the Sachica-Puente Samaca highway. A
tripartite division of the formation is observed;
(a) a basal unit consisting essentially of gray,
thick-bedded, quartzose sandstones with thin
interbeds of claystone and siltstone; (b) a mid·
dle interval of lenticular limestone beds, sometimes
argillaceous, rich in Exogyra, which alternate
with claystone and siltstone as well as occasional
quartzose sandstones; and (c) an upper
unit comprised of massive beds of fine to medium
grained sandstones and equally massive
limestones interbedded with claystones and siltstones.
In general the formation changes facies
toward the west where it becomes more arena·
ceous. The three subdivisions of the formation,
from bottom to top, measure 105 meters (244
feet), 75 meters (246 feet) and 225 meters (738
feet), respectively, giving a total of 405 meters
(1328 feet). The fonnation thins toward the
north. Contact with the San Gil Group is con·
formable at some localities and transitional at
others whereas the relationship with the overl·
ying San Rafael is everywhere conformable.
Fauna collected from the Churuvita Formation
consists for the most part of bivalve mollusks;
they are not described in the present report;
after Etayo Serna (1968, p.41) the mollusks are
the following:
Exogyra boussingaultii Dietrich (non
D'Orbigny)
Plicatulopecten concentricus Brtiggen
Ostrea syphax Coquand?
Pecten tenouklensis Coquand
Exogyra squamata d'Orbigny
Paleontological data from the underlying
and overlying strata suggest that the unit may
be assigned to the Albian pars (?)·Cemomanian.
The report of Venezoliceras (?), previously
(cp.cit)tentatively assigned to the base of the
unit iS now considered unreliable information.
SAN RAFAEL FORMATION
· (Lower Turonian)
Etayo Serna (1968a) first proposed the
fonnation. As type locality he chose the que·
brad a whose source is 200 meters south of Chircal
San Rafael. The San Rafael Formation crops
out to the east of the Serrania de Arcabuco; it
is also exposed along the axis of the Churuvita
syncline. At its type locality, the formation
may readily be divided into: (a) a lower unit of
gray shales which weather to lighter tones with
minor beds of thinly interbedded limestones;
and (b) an upper unit consisting of thinly bedded,
siliceous siltstones with several narrow
bands of chert and toward the top, a single sha·
le bed. The lower unit of the San Rafael is 60
meters (197 feet) thick at the type section, the
upper unit is 14 meters (46 feet), giving a total
fonnational thickness of 74 meters (243 feet).
Whereas the lower unit is variable, the upper
one is of remarkably uniform thickness. From
the lower unit of the San Rafael Formation
near the axis of the Churuvita syncline along
the Sachica·Puen te·Samaca highway, several ce·
phalopods have been collected; Paramammites
colombianus n. sp., is described in the present
report.
CONEJO FORMATION
(Upper Turonian ? -Lower Senonian pars)
The Conejo Formation was first named
by Renzoni (1967; published in Etayo Serna
1968a). Its type locality is the Alto del Conejo
located on the Oicata.Chivata road, some 9 kilometers
(5.6 miles) due northeast of Tunja.
In the study area, the Conejo Formation crops
out on the folds forming the margins of the Sa·
maca-Sora Valley. The Formation is comprised
of three units: (a) an unnamed lower part con·
sisting predominantly of black shales with occa·
sional thin interbeds of fine·grained sandstones
or siltstones; (b) the middle, Cucaita Member
which is exposed in the core of the Cucaita an·
ticline. Its lower part is a series of calcareous
shales alternating with several sandy limestones
beds, the shales containing abundant calcareous
concretions. The member as a whole takes on a
whitish-yellow color due to the claystones toward
the upper part which become progressively
more arenaceous upward; and (c) an upper in·
t.;rval, also unnamed, composed of yellow·white,
quartzose sandstones intercalated with dark·
gray, usually sandy shales. Near the top of the
interval are found highly fossiliferous lenses of
limestone. The total thickness of the Conejo
Formation is 370 meters (1214 feet), divided as
follows: lower interval, 80 meters (262 feet);
Cucaita Member, 170 meters (558 feet); upper
interval, about 120 meters (394 feet). In the
area of this study, the contact with both the si·
liccous siltstones of the San Rafael Formation
and the overlying Plaeners Formation are con·
fom1able. The middle, or Cucaita Member, has
yielded the following assemblage described in
the systematic part of this report.
Nice{oroceras boyacaense n. sp.
Peroniceras robertogarciae n. sp.
Peroniceras diabloi n. sp.
Peroniceras guerrai n. sp.
Prionocycloceras (?) cucaitaense n. sp.
Gloriaceras correai n. sp.
7

8
Gloriaceras paulinae n. sp.
Zumpangoceras ospinai n. sp.
Zumpangoceras (?) sorae n. sp.
Buenoceras loboi n. sp.
Protexanites cucaitaense n. sp.
The uppermost part of the upper interval
contains fossils of early Santonian age, including
Lenticeras baltai Lisson.
PLAENERS FORMATION
(Santonian pars)
According to Julivert (1968), the Plaeners
Formation was frrst differentiated by Hubach
(1931). The type section is located on the Sabana
de Bogota, at "Boqueron de Tabio". The
Plaeners can be traced from its type locality in·
to the study area. It forms the prominent spur
observed to the east of the Samaca-Sora Valley.
The unit consists of a series of gray, siliceous
siltstones in beds of 5-20 centimeters (2-8 inches)
exhibiting rhomboidal fracture and rich in foramlnefera.
The siltstones are frequently intercalated
with beds and lenses of dark-gray chert
and occasional layers of phosphatic sandstone.
In the Quebrada San Joaquin, 50 meters {164
feet) are measured. The contact with the
underlying Conejo Formation is conformable
and with the overlying unit, gradational.
GUADALUPE FORMATION
Julivert (1968) states that Hubach in
1931 named {or perhaps more accurately, redefined)
this unit from exposures in Cerros
Guadalupe and Monserrate,immediately east of
Bogota. The sequence forms the uppermost
·p.rominent cliffs to the east of the Samaca-Sora
valley and represents the northern continuation
of the sandstone of the same name which is exposed
on the mountains surrounding the Saba·
na de Bogota. The lower part consists of beds
of siliceous argillites or siltstones, some of
which tend to fracture rhomboidally. The overlyingTierna
Sandstone is a white, yellow-weathering,
coarse grained arenite which exhibits pro·
mlnent cross-bedding toward its base. In the
studied area the argillites reach a thickness of
50 meters (164 feet) and the overlying sands·
tone 9 meters (30 feet). Contact of the lower
part with the Plaeners is gradational, and contact
of the Tierna Sandstone with the Guaduas
Formation is conformable.
WHE CRETACEOUS SECTION IN THE APULQ,
- VlOTA, LAS MESITAS REGION,
SEE TEXT·FJG. 2B.
·
L
A NAVETA FORMATION
·-?:·.-. . '""- ·r· ., ;.
.
. • - .
.
The' name was originally introduced by
Hubach (1931, p.44) to describe a sandstone
horizon; it has been granted formational ranking
by Caceres and Etayo-Sema (1965, p.5). Its
name comes from the cement factory of that
F. ETA YO· SERNA
name. The unit crops out as the core of the
Diamante anticline [Cerros del Diarnante to the
north, and Cerro del Trueno to the south 1. The
unit is well exposed on the road from La "Naveta
Cement factory to Ingenio Central San Anto·
nio (now Escuela Vocacional), just beyond the
bridge over the Bogota River, or on the west
limb of the El Diamante anticline where the type
section was measured. The La Naveta Formation
consists of a sequence of white to yellowish
quartzitic sandstones, medium to coarse
grained with frequent grains of chert; not very
compact, with interbeds of shale rich in plant
remains. The La Naveta Formation includes
three units of member rank.(!) pi_-m.;
... ber; its name comes from the Ctirros D1amante;
it consists of coralline limestones interbedded
with shales and sandstones, the upper beds are
19 meters (63 feet) thick; it has been mined for
use in cement. A specimen of Thurmanniceras
sp. was found loose near the outcrop of the
unit on the east flank of the El Diamante Anticline,
north bank of Rio Bogota. (2) 'Th . J?.j;
cal member; its name comes from Cerro de Bejiicanvnere
it has been mined.lt is a biostrome
of bivalves, worm tubes and a few corals. It
yielded in situ: Heinzia (Carstenia) sp. The total
thickness measured without having reached the
base of the La Naveta Formation is 243 meters
(801 feet).
VILLETA GROUP
This unit was established by Hettner {1892),
it has been thoroughly reviewed by Julivert
(1968); no type locality has yet been formally
proposed. The name was introduced in this region
by Hubach (1931, plate 1). Several units
with formational rank have been proposed within
the group; {1) the basal unit or Trincheras
Formation named" after its type locaiitfat Quebrada
Trlncheras. It consists of an alternation
of limestone beds very rich in bivalves; its age is
believed to be partly Barremian to Lower Ap·
J!:!l. The lower and upper contacts are confor·
mabie at the type locality. The formation crops
out forming a band around the core of the El
Diamante anticline; towards the northeast the
formation changes into shales. The thickness
measured at the type locality is 180 meters
(594 feet). (2) The. Sos2!Lfl1Tlatiqn. The·
.name was first used by Caceres and"Etayo-Sema
(1969, p.5); it is derived from Quebrada Socota.
This unit is intended to embrace the litho·
logic sequence from the frrst graded quartzitic
and calcareous sandstone at the base of the
Socota Member (to be described next) which is
-here taken as the basal member, and extending
up to the first occurrence of porcellanite beds
here considered the basal element of the
overlying unit,_jhe_lliliL.Eormation. The type
locality of the So"CcifaF"OrfiiatiO'if'tinilong the
new road from Anapoima to Apulo, beginning
at km 3 + 320. Except for its basal member the
:socota Formation consists of a succession Of
shales, they are superficially variegated but dark
gray at depth; there are frequent calcareous
concretions and · ·:gypsum veinlets usually crossing
the bedding of the shales. The maximum
thickness of the unit is estimated as 150 meters

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 9
(495 (et). Two members are described in de-'
tail: {iij thQOTfiA -rlrIT'J.'l .-,E,;.f,_:--.... -...
TION measureu aoou .., me rs " teeL1 norou
of culvert No. 19 [Km 3+220) on the new road
Anapoima·Apulo.
XI Argillaceous limestone bed • . . . . 0.15 m
or 0.49 feet.
.
X Variegated calcareous shales with reniform
calcareous concretions, or lens-like argillaceous
limestones. At base of this segment,
"fP sample C • 199 yielded !llw.clites obli·
- quum (Riedel) . • • . . . . 8 m or 26 feet.
IX Calcareous shales with lenses of argillace·
pus limestones; crushed ammonites,bival·
ves; altop sample C • 200 yielded Riedeli·
"'-' tes obliquum (RiedeQ . . 1.8 m or 5[eet
VTII Argillaceous limestone lens ..... 1 m or
3.3 feet.
vn variegated shales, with intercalations of
thin layers of very fine grained calcareous
and quartzitic sandstones, with bands rich
in fragments of cephalopods and bivalves
................. 8 m or 26 feet.
VI TOP Quartzitic calcareous sandstones,
very finely to finely grained in parallel layers
of 0.001 m (or 0.003 feet); calcareous
concretions are locally present, they contain
crushed ammonites and bivalves . ...
11.50 m or 38 feet.
V Quartlitic calcareous sandstones, fine to
very fine grained, laterally tending to
appear massive, but regularly occurring in
parallel or wavy, fine to very fine layers
of 0.001 m (0.003 feet) thickness, locally
with calcareous concretions surrounded
by fragments of cephalopods or bivalves
or coarse quartzitic sand . • . . 15.50 m or
41 feet.
[V Light gray quartzitic, fine grained sands·
tone, massive, 1 m (3.3 feet? thickness,
with interspersed calcareous concretions
. . . . • 1 m or 3.3 feet.
UI Quartzitic siltstones with intercalations of
very fine grained sandstones; predominan·
tly parallel laminae of 0.001 m (0.003 feet)
thickness. Locally there are lenses with
rounded quartz grains up_ to 0.005 m dia·
meter and crushed ammonites and bival·
ves. Some lenses of limestone also occut . •
7 m or 23.5 feet.
II Calcareous quartzitic siltstones to very
fine grained sandstones with subparallel
to wavy lamination; calcareous concre tions
with fragments of cephalopods and sporadic
rounded quartz grains up to 0.001 m
diameter . • . . . . • . . 7.30 m or 24 feet.
BASE
Dark gray shale . . • • • . 4.5 m or 15 feet.
..
REFERENCE SECTION. SOCOTA MEM·
BER. The base of the measured section is
· near the culvert at K 4 + 06.
Variegated shales, partly covered.
V TOP. Dark gray, quartzitic sandstone,
calcareous, very fine grained to fine grained,
locally medium grained.Subparallel
lamination, with calcareous concretions
which seem to merge in to the envelop ping
surrounding rock; fossiliferous: at 1.4 m
(4.6 feet) from top, sample C-220yielded:
' G_olombiceras sarmientoi n. sp.
r. Xcantliohoplites bigoureti(orme n. sp.
i Clieloniceras(Epicheloniceras) pardoi n. sp.
at-4--m (13.2 feet) from top, sample C-222
yielded Ridelite!i_ esthersemae n. sp . • . . •
5.5 m or 18'"'fee C;· ,"-·

10 F. ETA YO -SERNA
coarse grained sandstone occur and the
rock tend to become massive . 7.1 m or
23.4 feet.
I Alternation of calcareous lenses up to 0.5
m (1.65 feet) thickness, which enclose
abundant fragments of cephalopods and
bivalves and also has rounded grains of
quartz up to. 0.001 m diameter, in &;Iternation
w1th sdtstones beds or fine gramed
quartzitic sandstones • • • 4.15 m or 13.7
feet.
The Socota Member is a particularly interesting
unit; it is missing toward the southwes·
tern part of the region but it increases notably
in thickness and areal distribution northeastwards.
amrtWrdJf:·dAlf?ro;rt!f·e
SECTION of its basal beds was measured
adjacent to the house of Hacienda Capotes. This
name was introduced by Caceres and Etayo­
Sema (1969, p.5), without description of type
section. This unit can be recognized by the
frequent occurrence of argillaceous, thinly
bedded limestones or the abundance of highly
fossiliferous calcareous concretions up to 0.5 m
in diameter distributed in layers; the top of this
unit is marked by the dominance of clay-shale
with frequent occurrence of small argillaceous
to slightly calcareous concretions.
Section of the basal beds of the Capotes
Member measured along the road from the casa
of Hacienda Capotes to Japon, it begins inmediately
adjacent to the house.
VIII Argillaceous limestone • • . 0
feet.
.5 m or 1.65
VII Variegated shales with calcareous concretions;
just above the underlying limestone,
sample C-255 yielded :
j Lyel/iceras pseudolyelliforme n. sp.
i Lyelliceras isaacleai n. sp .
..t:. Hypophylloceras wiedmanni n. sp . • . 2.5
f m or 8.25 feet.
VI Argillaceous limestone thinning and wi·
dening irregularly; sample C-255 x yielded:
"! Ne odehayesites columbianus (Riedel) . • •
0.5 m or 1.65 feet.
V Variegated shales with interspersed calcareous
concretions; argillaceous limestones
separated by variegated shales, with crushed
ammonites . . . . 1.8 m or 5.9 feet.
IV Variegated shales with lenses of limestone
up to 0.5 m (1.65 feet) thickness . . • . . .
2.7 m or 8.9 feet. • .
Ill Argillaceous limestone that tends to split
in thin layers . . . . . . 0.8 m or 2.6 feet.
II Variegated shales . . . 2.5 m or 8.2 feet.
I Argillaceous limestone . 0.8 m or 2.6 feet.
REFERENCE SECTlON of the bottom
of the Capotes Member, ·measured . aetnebegiilning
of trail to the power transmission tower,
just west of village of Tarapaca.
II Dark gray shale; three intercalated layers
of fossiliferous concretions. Sample C-12
yielded :
Neodeshayesites co/umbianus (Riedel) . ..
. . . . . . . . 1.2 m or 4 feet.
I Dark gray shales with very fine argilla·
ceous limestone beds and calcareous concretions
with crushed ammonites. 25 m
(82.5 feet) below sample C-12, sample
C-13 yielded:
Trochleiceras juliverti n. sp.
Douvilleiceras tarapacaense n. sp.
Carloscaceresiceras caceresi n. sp.
BASE . . . . . . . . . . . 60 m or 198 feet.
Hard, red-brick, Trigonia bearing limestone
(Trincheras Forrnation). At this
geographical point the Socota Member
is absent.
REFERENCE _SECTION for basal part of
the Capotes Member and'underlying units; this
section was measured at Cerro Bejucal, from
the machinery house of the limestone mine,
and extending SE along the abandoned road.
VIII Gray shales, sporadic calcareous concre·
tions . . . . . . . . . . . 50 m or 165 feet.
VII Variegated shales with gypsum veinlets,
calcareous concretions and thi n fossiliferous
limestones. At top of these shales,
sample C-169 yielded:
- Rinconiceras rinconi n. sp.
_.., Pla tiknemiceras colombiana n. sp .
.,. Ca rloscaceresiceras sp. . 30 m or 99 feet.
VI Variegated shales with gypsum veinlets,
calcareous concretions and thin fossiliferous
limestones. At top, sample C-170
yielded:
'l' Eodouvilleiceras pedrocarvajali n. sp.
,.. Neodeshayesites columbianus (Riedel)
_ J)·o chleicerasjuliverti n.sp. 12m or 40 feet.
V Variegated shales with frequent calcareous
concretions and lenses of fossiliferous limestones
. . . . . . . . . . . 9 m or 30 feet.
IV Variegated shales with gypsum veinlets
and locally abundant gastropods and bivalves
bearing concretions .... 27 m or
89 feet.
III Dark gray shales . ... 200 m or 660 feet.
II (Socotii"'·Member). Quartzitic graded bedded
sandstones; large blocks of limes­
- tone . . .Du(renoyio codazziano (Karsten)
. . . . . . . . . . · . . . ... . 10 m or 33 feet.

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 11
I (Trincheras Formation). Limestone in thin
beds . • . . • • • . . • . • . • . . • . • . • • . • • • • •
-· uu,.Q SUISlti .This formational
name was mtroucen this region by Hubach
(1931); its type locality is at Hilo on the road
to Cambao. Lithologically it is characterized by
an alterntion of liditet"or porcellanite& with
dark gray clay-shale . In the present report its
base is taken at the rm t occurrence of liditic or
porcellanitic beds. A good reference locality'ls
on the old road Anapoima-Apulo before entering
the Apulo alluvial terrace. The morphologic expression
of this unit is usually steep ciifs or high
peaks with rounded tops; the presence ofbrick
like siliceous fragments allows its presence to be
recognized in the field. Although i!n.P-i
of..a.I;Dln .P,nites are foundJr:t these rocks they were
not studiedl_'"the present Investigation.
UNNAMED UNIT. Above the previous
unit there is a succession of shales, not forma·
lly named, they did not yield any fossils during
the field studies.
..X,B..Q,.F,O.RMA'IlQN . . This for­
mational nairie was introduced in this region by
Caceres and Etayo- Serna (1969, p. S);it consists
of an alternation of thin limestones and dark
shales towards its base but towards the top it
conaists ofporcellanites or finely stratified cherts;
the succession at several reference localities fo·
llows.
REFERENCE SECTION, La Frontera Formatiori,
road Ctimaca:vtOli;at La Cabana. K23.
XII Dark gray, siliceous shale, finely lamina·
ted . . • • • . . . . . . . . 1.4 m or 4.6 2 feet.
XI Alternation of porcellanite& in layers up
to 0.15 m (0.49 feet) thick with gray to
maroon mud shale . . . • 4 m or 13.2 feet.
X Gray shales. • . . . . . . 1.5 m or 4.9 fe et.
IX Creamy porcellanites, sticky when wet,
with impressions of ammonoids . . . . . • .
1:6 m or 6.3 feet.
Vill Gray silt-shale very rich in compressed
impressions of "Inoceramus". . • . . . . . .
2.3 m or 7.59 feet.
Vll Maroon mud-shale and porcellanites • . . •
0.9 m or 3.0 feet.
VI Creamy porcellanites with abundant im·
pressions of ammonites and bivalves, with
some cherty concretions; the rock is stra·
tified in layers up to 0.25 m thick • • • • • •
5.1 m or 16.80 feet.
V Gray silt-shale with elliptical calcareous
concretions • • • • . . • 1,5 m or 4.90 fe et.
IV Creamy porcellanite stratified in layers up
to 0.2 5 m thick, with mud shale intercala·
tions; the porcellanite& tend to break in
small brick-like blocks.4.5 m or 14.8 feet.
·
Ill Dark gray, siliceous silt or mud shale, it
breaks in small slabs. Ammonite impressions
are frequent; there are interspersed
calcareous concretions up to 0.6 m In diameter
. . . . . . . • • • 14.3 m or 4 7.0 feet.
n · Dark gray , mud to clay shale, weakly to
moderately laminated, with elliptical cal·
careous concretions up to 0.5 m in diameter
. . . • • . . . . . . • • 7.7 m or 25.4 fe et.
I Dark gray, clay-shale, with petroleum odor,
there are interspersed limestone concretions
or lenticular beds up to 0.5 m; sample
C-300 yielded:
Mammites nodosoidesappelatus n. sp.
Mammites scutulatus n. sp .
Hoplitoides hemanmojicae n. sp.
Hoplitoides {?) sp . ind.
Franciscoites suarezi n. sp. ·
Fagesia zanellai n. sp.
Imlayiceras {?) ralphimlayi n. sp . • • • • • •
9.01 m or 30.0 feet.
.... R J;:R.E!.NG-CIIQ\':Ult.J.a .. frg!)._a
Formation 'Iriea8tired· at Hacienda La Giraldii,
at place where the formation forms the ridge
alongside the Bogota-Las Mesitas road, Km 27+
832.
Ill Dark shales, partly covered . • . • • . . • • •
II TOP. Fine layers of siliceous shales in alternation
with porcellanites, in layers dominantly
0.1 m (0.33 feet), with intercala·
tions of limestone beds up to 0.5 m (1.6
feet) . . 12.5 m or 41 feet.
I Finely laminated dark gray shales with in·
terspersed lenses of limestone up to 0.5 m
or 1.6 feet thickness, very compact, pyri·
tized, some of them are fossiliferous; sample
C-264 collected 18 meters (59.40 feet)
below the top of this interval yielded:
Hoplitoides lagiraldae n. sp.
Sample C-263 coiiected 11.2 m (37 feet)
below the preceding sample yielded:
Mammites fugax n. sp . . 39 m or 129 feet.
ROAD LEVEL
The laminated clay shales overlying the
Frontera Formation yielded sample C-134:
Prionocycloceras longispinatum (Basse).
Prionocycloceras portarum n. sp.
Codazziceras scheibei (Riedel).
Codazziceras fina n. sp.
COMMENTS
With respect to the lithostratigraphic
scheme utilized in the present report a further
comment is necesary. Some of the fossils ill us-

12 F. ETA YO · SERNA
trated in several of the early paleontological
works on Colombian Cretaceous: I.Lea (1841);
E. Forbes (1845 ); H .. Karsten.(1858); A. D'- O . r
bi!Wr(!B""2)i L_. jec:lel (1938), arne from the ·
Apulo , Vwta, Las Mesitas reg1on. The first
attempt to present a stratigraphic sequence of
the Cretaceous rocks of this region is that of E.
Hubach (1931), in a paper in which a geologic
map and a columnar section are presented ; fossils
were collected and preliminarily studied but
they were not described or illustrated and only
a brief account of them was later given by J!m.;__
istroffer .(t9E?1 presumably based on the mate
nil re'TerreCtO by Hubach . Hubach (Op. Cit.,
p.55) discussed the stratigraphic sequence
studied by him and the faunas with preliminary
identifications by C. Rhein listed in the text.
Of his lithologic units ("Horizons" in Hubach's
terminology) discussed, the most frequently
quoted has been that called "Horizonte
de Colombiceras (rY)" about which Hubach
wrote (Trad., lb., p. 57) "It has been possible to
study carefully the 'Horizonte de Colombiceras'
only in its upper part. These levels of the upper
part have been divided in the level of Hoplites­
Acanthoceras (IV c), in the level of ammonitiferous
concretions (lVb) and in the level of Colombiceras
(IVa). The highest of these levels 1
which form together about 50 to 70 meters ot
the upper part of the horizon, consists of a
bank of lime composed of ammonites of the
group Acanth oceras-Hoplites, that can not be
separated satisfactorily. Furthermore, ch&racteristic
species of Hoplites and of Desmoceras:
D. Hopkinsi F., D. Mayorianus '! are observed".
However and unfortunately the levels
were numbered upside down in the stratigraphic
column on the left side of the geologic
map accompanying the paper, that is level (IV a)
appears as the highest and level (rYe) as the
lowest, but the expression "Nivel de Acanthoceras-Hoplites"
remains attached to the highest
level.
Breistroffer (19 36, p. 156) ave a list of
the fossits='ot-Hubach's levels thJS way: "Le
Gargasien correspond a !'horizon a Colombiceras
(IV) de M. Hubach. Sa partie inferieure
(rYa) renferme, a Viota-Capote-Apulo, Du{renoya
(?) nov. sp. (gr. Codazzklna Krst. sp., sub
Colombiceras Karsteni ap . Rhein). Sa partie
moyenne (rYb) presente, a Cerro del Capote,
Douuilleiceras solitae d'Orb.sp.( ::multinodosum
Rhein in litt.). Sa partie superieur (rv c) montre,
i San-Antonio, Phylloceras cf. Buchwnum
Forl)s sp. (sub Desmoceras Ma yorianus ? ap.
Rhein),· Pse udohaploceras Hopkinsi Forbes sp. ·
et Du{renoya nou. sp. (interm. entre D. lurensis
Kil sp. et D. texana Burckh.).Enfin, Ia locali·
te de Cerro del Capote (IVb-c) a encore donne
Brancoceras cf. aegoceratoides Steinm. (affinites
avec 1' Albien du Perou ). "
Here it is to be observed that there is a
precise correspondence between Hubach's enumeration
of levels in the text and Breistroffer's
usage of the roman numeration.
Hubach (Op. Cit., p. 45-46) had written
"In the Viota region, ascending the Cerro del
Capote, it is found, on the upper part of the
horizon of Colombiceras, first a bank of limestone
30 em thick, consisting exclusively of the
species of ammonite Colombiceras karsteni
Marcou. . . the horizon of Hoplites -Acanthoceras
is above that of the horizon of Colom·
biceras. The magnitude of the sediments that
separate both horizons does not seem considerable,
at most about 50 meters."
Evidently l:!istr?ffer was rong when he
used the expressiOn "I horizon a Colombiceras
(IV) de M. Hubach. Sa partie inferieure (IVa)"
because level (IVa) of Hubach's terminology
represents the base of the upper part of the
Horizonte de Colombiceras; unfortunately Hubach
used both the words horizon and level
(lb., p. 45,46) for two different things.
. Sub

ZONATION OF THE CRETACEOUS OF CEN TRAL COLOMBIA BY AMMONITES 13
tion a6 appeared on lJ. 720 (1963) and on
which the new term "Ubaque-Sandstein-Hypachanthoplites
Niveau" was Introduced. The
above discussed terminology is not followed in
the present study.
1--B-I_o ....
sT_R_A_T_W_ . _AP_H_Y R __ -[.
The following subdivision of the lithologic
sequences investigated in this report, based
on their faunal content (mainly ammonites),
that is their zonation, attempts to be in agree·
ment with the recommendations of the Intema·
ttonal Subcommission on Stratigraphic Classification:
"An International Guide to Stratigraphic
Classification, Tenninology, and Usage"
(1972). All the proposed zones in this scheme
are considered ••Assemblage-zones (Cenozones)".
The purpose-of estibliSJITng Oils zonation IS to--facilitate
the geological work currently being
done on the Cretaceous rocks of the Cordillera
Oriental Colombiana, and I am not attempting
to establish a rigid" Archetypical" scheme. I feel
it is important to have a reference element, an
objective starting point whose value it is hoped
will be challenged by others,
In other words, the subdivisions are
based on the succession of the paleontological
material collected in situ in the field and from
successive sequences of rocks as measured and
mapped at localities of easy access and unequi·
vocal identification. The lower boundary of the
units is established at the fll'S t known occurren·
ce of new taxa, especially genera; the upper
limits of the unit are consequently determined
by the occurrence of the next new groups at
the base of the overlying unit. Correlation or
time equivalence with the zonal scheme established
in Europe is not attempted in greater
detail other than the mere comparison of the
common occurrence of certain groups of
ammonites considered significant enough to
permit usage of the stage terminology for the
Cretaceous rocks as first proposed by_ d'Orbigny
and Coquand.
THE FOLLOWING ASSEMBLAGE ZO·
NES ARE HERE PROPOSED FOR USE IN CO·
LOMB lA.
As far as these studies demonstrate, the
zonal species have their rtrst appearance along
with the fU"S t record of Cheloniceras (EpichelonicerCI$),
Vectisites (Zambranoites), Riedelites,
Juandurhamiceras and GargasicerCI$, Cortezicenzs,
Pseudoptychoceras, Toxoceratoides (Colomboceratoides).
AS TYPE LOCALITY for the base of this
zo e the beds immediately above the white,
argillaceous (tuffaceous?) layer rich in compre·
sse specimens of ''Procheloniceras, cf. Proche­
lomceras albrectUJustriae Hoh." are selected.
These were previously recorded in Etayo-Sema
(1968), "Estacion 10e", columnar section Fig.3,
and "Est.lO", km. 28 on the road Sachica-Puen-
te Samac&, geological map. Lithologically this
zone is represented by La Paja Formation, sg
rE'lt
i!nt E as described by'"Etayo•Seiiia:,--1968. A
CE LOCALITY Cor the zone is the
previously described sections of the_ Socot8
Member on the road Anapoima-Apulo.
Species referred to the zone described in
this paper are:
Du{renoyia sanctorom Biirgl
Du{renoyia boteroi n. sp.
Du{renoyia codazziana (Karsten)
Stoyanowiceras treffryanus . (Karsten)
Stoyanowiceras cintatum n. ·sp.
Cheloniceras (Epicheloniceras) dognaeluirae
n. sp.
Cheloniceras (Epicheloniceras) camachoi
n. sp.
Cheloniceras (Epichelonicenzs) carlosacos-
tai n. sp.
Cheloniceras (Epicheloniceras) jimenoi n.
sp.
Cheloniceras (Epicheloniceras) barreroi
n. sp.
ChelonicerCI$ (Epicheloniceras) pardoi n.
sp.
ChelonicerCI$ (Epicheloniceras) leonhardtriedeli
n. sp.
Vectisites (Zamur-anoites) cadenai n. sp.
Vectisites (Zambranoites) crozi n. sp.
Vectisites (Za mbranoites) zambranoi n. sp .
Vectisites (Zambranoites) duquesi n. sp.
Vectisites (Zambranoites) mateusi n. sp.
Riedelites obliquum (Riedel).
Riedelites (?) quebradanegra n. sp.
Riede lites estheemae n. sp.
Juandurhamiceras juandurhami n. sp.
Juandurhamiceras giraldoi n. sp.
Gargasiceras interiectum (Riedel).
Gargasiceras pulcher (Riedel).
Corteziceras cortezi n. sp.
Pseudoptychoceras gilberti n. sp:
Toxoceratoides (Colo mboceratoides) renzoni
n. sp .
Aconeceras gutierrezpalmae n. sp.
Melchiorites palmeri n. sp.
Eogaudryceras helmsi n, sp.
Eogaudryceras (Eo te tragonites} cabaricoi
n. sp.
Pseudohaploceras le ivaense n. sp .
. Valdedoella (?) colombiana n. sp.
Colombiceras sarmientoi n. sp.
Eodouvilleiceras (?} tequendamai n. sp.
Colombiceras foreroi n. sp.
.P..lil. . aJ.Jw!HI.Gbi. · &gatfJahQuli&
.J!_ptocerati{orme Ass :_ ml Se - zone
As far as known to me these species have
their most occurrence in this part of the sequence;
the absence of Cheloniceras (Epicheloniceras},
Du{renoyia, Stoyanowiceras, Vectisites
(Zambranoites), Aconeceras, Eogaudryceras,
seems indicative also.
AS TYPE LOCALITY for the base of
this zone the clay-shale beds with abundant
argillaceous-calcareous concretions at point
C-127 on the road Anapoima-Apulo is design-
-

14 F. ETA YO · SERNA
ated. In the lithostratigraphic nomenclature it is
represented by the unnamed sequence of shales
overlying the Socota Member and below the
Capotes Member of the sequence in the region
of Apulo, Viota, Las Mesitas,
Species referred to the above named zone
Parahoplites (?) hubachi n. sp.
Parahoplites (?) tristan n. sp.
Acanthohoplites bigoureti{orme n. sp.
Acanthohoplites luisperezi n. sp.
Acanthohoplites seunesiforme n, sp.
Acanthohoplites pluricostatum n. sp.
Acanthohoplites eleganteante n. sp.
Acanthohoplites (?) leptoceratiforme n.sp.
Acanthohoplites (?) serpenti{orme n. sp.
Riedelites (?) filosum n. sp.
Corteziceras latecostata (Riedel)
Melchiorites media Riedel
Both preceding zones represent the pPr
.1\Rtian of Colombia. The tenn Aptian proposea
by· d'Orbigny (1840, I, p. 631) is here adopted;
its previous use in the stratigraphy of the Creta·
ceo us of Colombia has been thoroughly reviewed
by the author (Etayo-Sema, 1964). I find a general
agreement, in broad sense, between my
succession of faunas and those discussed by
Breistroffer (1947), Casey (1961), and Thomel
(1964) for the European uPper Aptian.
As far as known these two species have
their first occurrence in this part of the sequen·
ce. All the genera recorded for the preceding
zones are absent, but this is not so when com·
pared to Europe; the new species listed below
occur for the first time.
AS TYPE LOCALITY for the zone is
selected the same type locality as for the basal
·· part of the Capotes Member, however litholo·
gical characteristics and fossils do n.:t necessa·
rily correspond; as a REFERENCE LOCALITY
the same reference locality as for the Capote&
Member is designated. Other species belonging
to this zone are also given:
Ho/cophylloceras hernandezi n. sp.
Douui/leiceras abozagloi n. sp.
1Jouuilleiceras tarapacaense n. sp.
Eodouuilleiceras pedrocarvajali n. sp.
Neodeshayesites karsteni (Marcou)
Neodeshayesites albertoalvarezi n. sp.
Neodeshayesites cingulatum n. sp.
Neodeshayesites contracta (Riedel)
Carloscaceresiceros monteroi n. sp.
Carloscaceresiceras caceresi n. sp.
Trochleiceras (Trochleiceras) .
juliuerti n.
sp.
Trochleiceras(Jaumaportaiceras) hof{ste·
tteri n. sp.
Elatilmemiceras .colombiana-R inconiceras
rinciiniLjielliceras pseud01ye1Ufor"!e -
_5ssembly .
Some of the preceding species also occur
in this zone but the faunal spectrum changes in
favor of Lyelliceratidae and Engonoceratidae.
AS TYPE LOCALITY of this zone is
chosen the "Estacion 33a" previously recorded
by the writer (1968), columnar section Fig. 9,
and on the geological map annexed to that
paper. Lithologically at its type locality this
zone is represented mainly by "Nivel 8" of the
"Segment B" of the Upper San Gil Formation.
At the type locality the name-bearing species of
the zone have not been recorded yet. AS REFE· .
RENCE SECTION where the species occur are,
first the clay-shale concretions bearing succession
found at Cerro Bejucal, extending SE
along the abandoned road and from the machi·
nery house of the limestone mine.
Other species generally occurring in
the zone are :
- Engonoceras (?) duartei n. sp.
-Xnemiceras semicostatum Sommermeier
-J(nemiceras pegnai n. sp.
-Engonoceras olgaluciae n. sp.
tTegoceras benavidescaceresi n. sp.
):-Lyelliceras pseudolyelliforme n. sp.
'Lyel/iceras isaacleai n. sp.
Ralphimlayites apuloense n, sp.
The last two assemblage-zones discussed
represent the lpwer Albian and the base of the
Middle Albian jn Colombia. The tenn Albian
proposed-by a'Or6lEliY"-

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 15
Other species occurring in thla zone am:
-·· Mammites scutulatus n • .sp.
--Hop/itoides hemanmojicae n. sp.
... Fagesill zanell6i n. sp.
_ Imlayiceras (?) ra/phimlayi n. sp.
- Mammites {ugax n..sp.
- Hop/itoides lagiraldae n. sp.
- Paramammites co/ombitznus n. sp.
1bis zone ia here considered to represent
tile lower Turonian of Colombia. The Turonian
Staie';--pl(i'd '"'by d'Orbigny (1842) 1a aJao
adopted; its previous use in the geological literatuft!
on Colombia has already been discussed by
the author (1964). The affinities of the listed
fossils am given in the systematic descriptions.
G/oriaceras con-eai-Pro texanltes
cucartilense:Codliizrceras scheroei
ml!£e.zone
As far as known these species occur for
the first time in this part of the sequence.
TYPE SECTION of the zone Is the expo·
sores of the Cucaita Member at "Estaciones 6-9"
on the road Cucaita· Piedra Gorda as previosly
recorded by the author (1968, p. 45, Fig. 13,
and annexed geologic map); a REFERENCE
LOCALITY is the less accessible outcrops of
the beds above the La Frontera Formation
(Coordinates 42000W-979000N, . on Plancha
M6·1·A, Cundmamarca of the I.G.A.C.).
Other species consideed belonging to this
zone are:
..aloriaceras paulinae n. sp .
...Peroniceras solorzanoi n. sp .
... Peroniceras dillbloi n. sp.
...Peroniceras guerra/ n. sp.
....Prionocycloceras longispinatum (Basse)
-Prionocycloceras portarum n. sp.
..Prionocycloceras (?) cucaitaense n. sp.
-Nice(oroceras boyacaense n. sp.
-zumpangoceras ospinai n. sp.
.-Zumpangoceras (?) sorae _. sp.
This zone is here considered to represent
the lower Coniacian. The term Coniacian as
proposeci"""by"'d0qu8iia (1857, p. 748) is here
adopted. Similar faunas occurring abroad are
discussed in the taxonomic part of this report.
Lenticeras baltoi-Paralenticeras sieuersi
Assem6lage-zone
The name-giving species have previously
been discussed by the wnler (1969). . .. ·· . . .
The TYPE LOCALITY for the .zone Is
the outcrop of the upper part of the' Conejo
Formation and below the Upper Lidita'Forma•
tion, about 100 meters south of well .B·20, as
depicted by the writer on the Geologic map of
the Villa de Leiva Area, near the road·Puente
Samaca-Cucaita (1968). The Santonian . Stage
also proposed by Coquana1t857,-p -749) is
here stressed, however the basis for Its recognition
is not especially strong when the poverty of
ammonites now known from Colombia is considered.
The proposed zonation is summarized in
Table 1.

16 F. ETA YO · SERNA
TABLE I
ASSEMBLAGE ZONES PROPOSED FOR USE IN COLOMBIA
z
<
-
z
0
E-<
not represented
z
<
Cll
Len ticeras baltai Paralenticeras siiwersi
z
<
-
0
not represented
< Gloriaceras correai Peroniceras diabloi Niceforoceras
-
z
0 Protexanites cucaitaense Prionocycloceras (?) cucaitaense
0
Codazziceras scheibei Z umpangoceras -ospinai
z
<
-
z
not represented
0
Mammites nodosoidesappelatus Hop litoides lacabagne Fagesia zanellai
0
E-< Franciscoites suarezi Mammites fugax Paramammites
0
+ not represented
<
Platiknemiceras colombiana L_y_e lliceras carvajalorum
z Rinconiceras rinconi Knemiceras pegnai
< LyeUi9as pseudolyeli.iforme Engonoceras (?) duartei
- -
-
..::I Neodeshayesites columbianus R:ZIJ_himlayi_ts Jaumaportaiceras
<
Carloscaceresiceras caceresi
Douvilleiceras solitae Neodeshayesites karsteni
Parahoplites (?) hubachi Acanthohoplites (?) lep toceratiforme
z Juandurhamiceras Riede lites
<
-
E-<
(:I._
<
Stoyanowiceras treffryanus
.
.
Corteziceras
Aconeceras
Zambranoites Colombiceras
Co lorn boceratoides Gargasiceras
Pseudoptychoceras Epicheloniceras
Dufrenoyia sanctorum Melchiorites Pseudohaploceras

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 17
SYSTEMATIC DESCRIPTIONS
Phylum MOLLUSCA
Class CEPHALOPODA
Order AMMONOIDEA
Family PLLRATIDAE
Genus I Ph ]lote Suess, 1866
Phylloceras Suess, 1866, p. 7.
TYPE SPECIES. Ammonites heterophyUus
J. Sowerby, original designation.
Phylloceras. buchjqnu;(Forbes) ?
PI. 8, F1g. 4; Text- 1g. 3C.
1844 Ammonites Buchilzna Forbes, p. 177,
Fi· a,b, under the species name.
? 1858 Ammonites Buchilznus Forbes, Karsten,
p. 84.
1881 A. r mmonites.] BuchitJna Fbs., Hyatt,
p. 3'10.
1883 [Phylloceras] BuchitJna Forb., Uhlig,
p. l82.
' ' ·
1907 Amm. [onitesl Buchiana Forbes, Prvinquiere,
p. 50.
1910 Ph. fylloceras] Buchianum Forbes,
Fallot, p. 70.
1920 Ph. [ylloceras] BuchitJnum Forbes,
Gignoux, p. 91.
1923 Ammonites Buchiana, Forbes, Bose,
p. 125.
1923 Ph. [ylloceras] buchitJnum (Forbes),
Spath, p. 17.
1924 Ammonites buchiana Forbes, Sherborn,
p. 925.
? 1936 Phylloceras cf. BuchitJnum Forbes,
Breistroffer, p. 156.
? 1955 Phylloceras cf, BuchitJnum Forbes, ex
Breistroffer, :aurgl, p. 13.
1964 Phylloceras buchianum (Forbes), Etayo
Serna, p. 101. pars.
Holotype B.M.N.H. .
Hypotype C-217. (U.N.C.M.H.N.C.P.Hy. N.1)
I am referring to this species a group
of small, inflated and Involute conchs; they ha·
ve a broad venter and convex sides that round
abNptly into a deep umbilicus.
The adapical part of the last preserved
whorl of the hypotype has low, broad, subdued
leats especially visible with oblique illumina­
tion. These pleats have a sinuous trend, they
describe an arc on the inner half of the flank
and a broad adoral concavity on the adventral
half, they project onto the venter fanning an
adoral arc. The pleats increase their width slowly
but steadily towards tho venter.
There are shallow but wide constrictions
that approximately follow the trend of
the ribs but project strongly forward as a lingui·
fonn arc on venter; they are weU developed on
the internal mold but only as broad and low
areas on the surface of the test. On the adoral
portion of the last whorl the shell Is preserved
and the pleats are well defined as flattened belts
of growth striae wider than the intercostal
spaces. These belts stretch approximately to the
adumbilical third of the flank .where they fade
out and only fine raised growth lines extend
toward the umbilicus. The periumbilical area
seems smooth. Strigations are visible especially
around the umbilicus.
The suture line has L. trifid,., , _
DIAGNOSIS. This species Is characterized
by: A) its sinuous, low ribs especially developed
on the external half of the flank, B) the lingui­
fonn projection of the constrictions on 'ventei:
on the intemal mold, C) the broadly rounded
section of whorls on venter.
Meuuremenu. D Euw H W DfEuw % D/1{%
Hypotype 14 3 ?7 8 21 ?60
COMMENTS. This peculiar species has
been synonymized with P. uelledae (Michelin)
d'Orb. [Fallot, 1910, p. 70; Gignoux, 1920, p.
91], but Spath (1923, p. 17) has given it
specific standing because "It is more inflated
throughout"; in Forbes' species the periventral
and ventral zones fonn a broader arc than in P.
velledae. Phylloceras moriezense Sayn (1920,
p. 194, pl. 1, Figs. 2,3) has a similar develop·
ment of the ornamentation but the whorl
section seems less inflated and its ribs are clearly
rounded in contrast to those of Forbes' species.
However on both species the ribs are slightly
projected on venter.
OCCURRENCE. Capotes Member.
Genus \Holcophylloceras]Spath, 1927.
Holcophylloceras Spath, 1927, p. 38.
TYPE SPECIES, Phylloceras mediterraneum
Neumayr, original designation.
Holotype C-13 (U.N.C.M.H.N.C.P.Ht. N. 1)
Paratype C·13 (U.N.C.M.H.N.C.P. Pt. N.1)
In the juvenile the conch is inflated, na·
rrowly umbilicated, the umbilicus is deep; the
conch Is divided into protruding segments by
biconcave constrictions that are Ungulate on
venter, when the shell is preserved one adapical
ridge parallels the contrictions; the omamenta-

18 F. ETA YO ·SERNA
tion consisfli only of rme growth lines that tend
to form almost imperceptible bands that para·
Del the constrictions and ridges. There are seven
constrictions on the preserved last whorl.
The section of the whorl is subquadrate,
slightly wider than high, it has flat parallel flanks
which are weakly beveled at the periventral
margins producing a narrow venter; the umbilical
wall is oblique on the ad apical segment of the last
whorl, it is subvertical on the adoral portion.
There are seven constrictions on the last preserved
whorl. 'The suture line has subrectangular
bifid saddles and wide, slightly asymmetrical
tripartite lobes.
In the adults the whorl section is subquadrate,
slightly wider than high; the flanks are
flat but round into a narrower feebly arched
venter; the periventral z one is feebly beveled.
The umbical wall is subvertical and the umbilical
rim is rounded.
The conch is divided into segment"$ by fi.
ve wide and shallow constrictions on the internal
mold,these are represented by very feeble
low zones on the shell and are rimmed ad orally
by a slightly thickened ridge. 'These constric·
tions follow the trend of the growth Iirae.
'The ornament consists of raised growth
lirae that gather and crowd in broad, flat,
rib·like sheaves; now and then these sheaves
may raise as low ribs, they begin at the umbilical
seam where they form a minute adoral concavity
just near the umbilical seam from which
point they trend prorsiradiate up to the adumbilical
third of the whorl where they bend
abruptly to form and arc on the middle and
part of the ad ventral thirds of the flank; on th
periventral margin they forin a conspicuos
adoral concavity and on the venter form an
acute adoral arc. The internal mold in covered
by low undulations corresponding to the
sheaves of striae.
The suture line has phyUoid bifid saddles
with narrow bases; E/L is bifid and its external
branch is also bifid and its lower branch contacts
the midventral saddle.
DIAGNOSIS. This species is characterized
by: A) the conch divided into protruding segments
between deep sinuous constrictions, lingulate
on venter in the young, B) flattened segmenbi
of the conch between attenuated constrictions
in the adult, C) its falcoid sheaves
of lirae stressed adventrally, and D) its quadrate
whorl section with feebly beveled perivenargins.
i '
Meuurementa D
Holotype 21
Pmtype 13
EuW H W E(Euw •fJ)fH'%
6 10 11 24 48-
3 7 8 23 64
- COMMENTS. The early whorls of this species
resemble Va ldedorsello getulina (Coquand)
as Ulustrated by Pervinquiere (1907, p. 151, pl.
6, Fig. 16), but the latter has a depressed whorl
section. The Tetrogonites-Iike aspect of the adult
whorl is a mere chance morphological similarity
because in contrast to the latter genus the Colombian
species has L tripartite.
These striking differences between the
juvenile and adult whorls are of common occurrence
in Phylloceratidae (see Wiedmann, 1963,
p.186); the specimens I consider conspecific
came from the same concretion and are similar
in the development of the subquadrate whorl
section.
Of the Cretaceous species referred to this
genus, Holcophylloceras guettardi (Raspall) [in
Wiedman,. 1963, p. 258, ,Pl. 17, Fig. Sa, 8b] ,is
most sirnil.ar to my spec1es. In the European
species thew horl section is rounded (Wiedmann,
ibid, text-Fig. 62a). In the Colombian species the
growth striae are accentuated adumbilically
contrary to those of the Mallorcan species.
This species is named in honor of the zoo·
logist Jorge Hernandez, of the Universidad Nacional
de Colombia.
OCCURRENCE: Capotes Member. Lower
Albian.
Genus l Hypophyllocer3Salfeld, 1924.
Hypophylloceras Salfeld, 1924, p.5
TYPE SPECIES. Phylloceras onoense Stanton,
original designation.
Jil'llPDlWiacerg§ wjed:WIJ.i n. sp.
Pl.10, Fig. 3; Text-Fig ·
? 1938 Phylloceras velledae Mich. var seresitense
Perv., Riedel, p. 8, pl. 4, Figs. 6,7;
pl. 12, Fig. 7, pl.14. Fig. 1.
? 1968 Phylloceras serecitensis sensu Riedel
(non Perv .), Etayo-Sema, 1968, Fig.3,
Table I.
Holotype . C-255 (U.N.C.M.H.N.C.P.Ht. N.2).
The conch is involute, narrowly umbilicated,
the umbilicus is rimmed by a narrow plano·
concave surface. The adumbilical half of the
whorl has an almost smooth surface on which
with adequate illumination, the extension of the
ribs are visible as rm e threads. The adventral
third of the whorl-side is convex and covered
with fme, rounded ribs, separated by subequal
intercostal spaces up to twice as wide as the ribs.
The boundary between the callused and ribbed

ZONATION OF TilE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 19
and tend to fonn bundles some of which beco·
me more prominent near the adumbilical third
of the whorl side that appelll'll
as a surface covered
with irregularly distributed pleats. The section
of the whorl has a broadly rounded venter
and flattened diverging flanks which at the urn·
bllical rim attain their ,!Daximum width and
then tum abruptly into the. oblique umbical rim.
No living chamber is available.
DIAGNOSIS. This species is characterized
by: A) the callused ad umbilical half of the whorl,
B) the channel-like intercostal spaces, the broa·
dly arched trend of the fme rounded ribs on the
flanks, and their feeble projection on venter,
C) the whorl section with broadly rounded
venter and central third of the flank flattened,
and D) the plano concave adumbilical surface.
Meuurementl D Euw H W DfEuw % D/H.04
Holotype 46 6 24 18 13 54
COMMENTS. On Riedel's specimen of
Phylloceras velledae Mich. var. seresitensis Perv.,
from Utica, not far from the region studied in
the present report, (see especially Riedel's illus·
tration of the internal whorl, pl.4, fig.6) the
adumbilical half of the whorl is eroded so the
callused co,yering and urdrlying fme. ribbing
can not be recognized, but Riedel remBl'ks:
"Los flancos estan cubiertos de numerosas listas
finas que, naciendo aproximadamente a media
altura de las espiras, siguen derecho bacia el
!ado extemo, donde forman un arco apenas
perceptible hacia adelante". Riedel commented
that his specimen does not' show the falciform
trend o"f the ribs as in Ph. velledae Michelin (see
the figured cast of the neotype of this species in
Wiedmann, 1963, pl.12). The lectotype of Ph.
seresitense Pervinquiere (1910, p.9, Fig. 2, pl. 1,
Fig. 1; se·e Wiedmann, 1963, p.222) shows a
flattened surface of the flanks that descends
funnelwise to the umbilicus, this surface is
reduced to a mere rim around the umbilicus in
Riedel's figured specimen and in the present
specimen.
Wiedmann, the last reviewer of the
group (1963), recognized three "subspecies" of
Ph. seresitense based on the section of the whorl
and the width of the umbilicus. In the present
species the umbilicus is narrow and the section
of the whorl, like that figured by Riedel (1938
pl,. 12, Fig. 5) has a broadly rounded periventrai
shoulder rather than beveled shoulders as seen
i the lectotype of PerVinquiere (1910, pl. 1,
F1g. lb) and the hypotype figured by Wiedmann
(1963, pl.21, Fig. 1b).
. The. flattening of the flanks in the Colom-
bian spcunens produces a middle third of the
whorl 11de that diverges from the venter and
en pptly rounds into the umbilicus; in Per­
\'Ulqulere s illustrations, both middle and
adumbilical thirds of flanks are flattened but
sho"! . a. tendency to converge toward the
umb1cal rim. Wiedmann used the flattening of
the s1d s as a specific character (1963, p.202·
203, F1g_. 47b): Phy/locerrl$ (Hypophylloceros)
subserec1tense Wiedmann. The trend of the ribs
In the latter species is radial to slightly concave
adorally (?) (op.cit., pl. 15, Fig. 6) on flanks.
The subspecies P. (H.) seresitense tanit Pervin·
quilre (Wiedmann, p. 228, fig. 54) has a biconcave
type of ribbing.
This new species is named in honor of
Dr. Jost Wiedmann, of the Tiibingen Universitat,
West Germany.
OCCURRENCE. Capotes Member. Lower
Albian. Paja Fonnation (Arcillolitas abigarradas
Segment E.). Upper Aptian.
Family GUJ R;;cTIDAE
Genus \E

20 F. ETA YO ·SERNA
increasing overlap of the whorls with age. pressed; the sides and venter are nattened.
DIAGNOSIS. This species is characterized
by: A) the change in shape from subcircular to
rounded rectangular cross-section in the ontoge·
ny, B) the bundle fonning convex Urae, and
C) the lack of 'constrictions' in later stages of
growth.
Meuurementa D Euw H W DfEuw % D{H %
Holotype 17 8 11 1& 41 61
COMMENTS. This species differs from
Eogaudryceras vocontianum (Fallot) [1921, p,
233 b pl. 2, Fig.2] because the lirae are radial ('!)
on ank of his species, (Fallot, op.cit., p.235)
and the constrictions are accentuated, further·
more its maximum thickness is toward the umbilical
margin whereas in the Colombian
species it is located toward center of the flank.
The specimens of Fallot's species referred to by
Wiedmann (1962, p. 40, pl.2, Figs. 2,6,8) as
showing variation of the width of the section
(ib., p.41), clearly show a high vaulted section
also. From Eogaudryceras numidum var. inter·
mediLJ (Fallot) f1920, p. 235, 1?1.2, Fig.3: lecto·
type, Breistroffer, 1947, p.56j the Colombian
species differs because its cross section profile is
more evenly rounded and wider and the less
accentuded constrictions on its flanks attenuate
very early.
This species is named in honor of Dr.
J. Helms of the Humboldt • Universitat in Ber·
lin, DDR.
OCCURRENCE. Socota Member. Upper
Aptian.
Subgenus . (Eojetraponites1nreistroffer, :[D
19 7.
Eotetragonites Breistroffer, 1947, p. 56.
TYPE SPECIES. Lytoceras (Tetragonites) depressus
Raspail, original designation.
.. fogaudr:x,ceras (E otetrag,onites2 cabaricoi,..
n. sp.
Pl. 6, Fig.ll; Text-Fig. 3M, 3N.
Holotype. C-513. (U.N.C.M.H.N.C.P. Ht. N.4).
On the earliest whorl observed (the se·
cond?) the section is reniform, wider than high,
it has a broadly rounded venter; the whorl sides
are convex and round into a vertical umbilical
wall. The ornament on the internal mold con·
sists of rounded prominent undulations which
fonn feeble adoral arcs on the whorl side, they
are separiid by constriction-like low zones; on
the test fine transverse lirae are visible on venter.
On the_ th.. _whorl· [of the paratype ] the omamnt
consiits of bundles of striae, but wide
constrictions that follow the pattern of the
bundles develop on the opposite sides of the
whorl without crossing the venter. On the third
whorl, the whorl section is subquadrate and
has a clear tendency to become higher than de-
DIAGNOSIS. This species is characterized
by A) the ontogenetic changes of the section of
the whorl from renifonn in the inner whorls to
subquadrate In the outer whorls, and B) the
sporadic strong constrictions that do not cross
the venter.
Meuuements. D Euw H W D(Euw % D{H%
Holotype 26 6 11 14 24 44
COMMENTS. This species is comparable
to Eotetragonites jacobi ambigua Breistroffer
f= Guadryceras in termediLJ Fallot, 1920, pl. 2,
Fig. 6, 10), from the French Gargasian but on
the latter species the constrictions are more numerous
and frequent than in the Colombian species
which furthennore is more robust and involute.
This species is named in honor of Mr. Ma·
nuel Cabarico, of the Geological Survey of Colombia.
OCCURRENCE. Socoti Member. Upper
Aptian.
Family
ncM -c Genus
Toxocerat6ides Spath, 1924, p. 78.
TYPE SPECIES. Toxoceras royeriLJnum d'Orbigny
(I.C.Z.N.?).
Subgenus-? {QiJo}itbog}!!!J
n. subge-
::- 7Q not/a,. o'kJ nUS , fp

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 21
area the ribs describe a wide adoral arc and on
both sides of this arc two narrow adoral conca­
vities are formed; the ribs then trend obliquely
and slightly arcuately across the flanks and fl.
nallY they cross normal to th ventral medial
axis where they become depressed and even
very attenuated but not lnterrupted. The inter­
costal spaces are channel like with rounded
bottom and usually subequal in width to the
ribs but occasionally are a bit wider. The moilt
adapical preserved segments of shaft have ribs
of uniform strength that bear low, rounded to
compressed bullae on either side of the vef\tral
median depression;· now and then however a
fmer, almost ventrally nontuberculated rib
occurs, likewise stronger and ventrally noded
ribs are intercalated.
With maturity a clear differentiation of
the ribs occurs: one non stressed rib alternates
with one strong rib which bears one spinose
tubercle on the periventral margin and a second
mammiform tubercle at the boundlllY betwen
the peridorsal and central thirds of the flank;
the costal whorl section acquires a beveling of
its profile on the adventral third of the flank.
With further growth the primlllY ribs develop
an additional, smaller, mammiform tubercle
near the rim of the dorsal side but the ribs are
nearly interrupted on venter, developping a weak
channel along the ventral median line; two
intercalary ribs may occur on mature stages.
Later the section of the whorl becomes roun·
ded subrectangular, the segment of the ribs
between the ventral and lateral tubercles is
flattened, with a tendency to split longitudinally.
DIAGNOSIS. This species is characterized
by A) the rapid increase in width of the shaft,
B) the ontogenetic development of its ornament
from undifferentiated barely tuberculate ·ribs,
not interrupted on venter, to an alternation of
trituberculate primary ribs and almost non tu·
bereulate intercalatory ribs all of which become
attenuated on venter, and C) the progressive
development-of the lateral tubercles.
COMMENTS. This species differs from
.Toxoceratoides royerianus ("d'Orbigny) as emen·
ded by Casey (1961, p. 77) because the ribs do
not divide on the dorsum or if they do no more
than two riblets appear; they differ also in the
suture line which is less complicated in the Co·
lombian species. However this difference may
be due only to the diameter of the whorl at
which the sutu:res were drawn.
. This species is named in honor of the geo·
logqt Giancario Renzoni.
• OCCURRENCE. Paja Formation (Arci·
llolitas ablgarradas. Segment E.). Upper Aptian.
Toxcerutoides (Colomboceratoides} ren­
zom n. sp.
. (Morph I).
Text-Fig. 3P.
Paratype. (U.N.C.M.H.N.C.P.Pt.N.2.)
The shaft Is slightly arched. The early section
of the whorl is vaulted; the dorsal area ia
arched with the sides rounding outwardly up to
the center of the whorl then evenly rounding
toward venter which is flat.
The ornament consists of prominent
rounded ribs which cross the dorsal area linearly
or with a slight adoral bow, they cross the
flanks forming frst a weak adoral concavity on
the dorsal rim and then trending prorsiradiate
or describing a slight arc, or even forming an
adoral concavity; on venter they become interrupted
-on the internal mold- or very attenuated
on exterior of the test around the ven·
tral medial line; the end of the ribs converge
toward the siphonal line forming a wide V with
its apex pointing adorally. All ribs •develop
rounded to spinose periventral tubercles. Though
sporadically one rib may show greater strength,
the ribs gain strength progressively and do not
develop a regular alternation of strong and
weak ribs. The intercostal spaces are deep and
twice as wide as the ribs on the internal mold,
but they appear shallow and narrower when the
shell is preserved. · · .
NOTE: This morph is notabl_e- for the steady
growth of the section of the shaft, by
the strong, uniform and unituberculate
ribbing and the early stressing of the
ventral tuberculation.
OCCURRENCE. Socoti Member. Upper
Aptian.
Family P Y HOCERATIDAE.
Genus 1 Pse udoptychoceras n. (}
.=:: £o.plyrh11u -""A.
TYPE SPECIES. Pse udoptychocerrzs gilberti n.
sp.
DIAGNOSIS. Straight or slightly undula·
ted, slowly increasing initial shaft, ornamented
with prominent, oblique annular rounded ribs,
separated by conspicuous constriction-like intercostal
spaces; the section of the whorl is elliptical
to almost circular, the first shaft bends to
a shorter (?) branch which leaves an opening
("needle hofe") before appressing against the
:lorsum of the first shaft; this second branch is
ornamented with annular acute ribs distant
from each other. The suture line has short sub·
rectangular elements, relatively undisected, L
Is trifid.
COMMENTS. This new genus differs
from Ptychoceras because of its loop forming
hook and its trifid L; from Euptychoceras
(Breistroffer, 1947) because the fanner Is
smaller and has strong ornamentation on both
shaft and hook.
Pseudoeachoceras gjlberti, n. sp.
P[G, li'ig. 18; Text-Fig.3S, 3T.
Holotype. C-223 (U.N.C.M.H.N.C.P. Ht. N. 6).
Paratype. (U.N.C • .M.H.N.C.P.Pt. N.3) .
There are three fragments of the shaft,
two of them with part of the hook preserved.
The shaft is straight, progreSBively tapering, It

22
has a subelliptical to subcircular section: the
dol'Bal region is wide, flattened, abruptly changing
into the feeble convex sides which evenly
round toward the narrow arched venter. There
are broadly rounded, low ribs, slightly thickened
on venter. On the dorsal area the ribs are
barely visible, they cross it as fm e lirae normal
to the dorsal-central axis; at the margins of the
dorsal region the ribs become well defmed and
cross the flanks of the shaft in an arc convex toward
the hook; they cross the venter normal to
the ventral-central axis; the intercostal space,
constriction-like in appearance, is prominent
on flanks and venter and subequal to slightly
narrower than the ribs.
The beginning of the hook Is indicated by
three narrower ribs which appear as a bundle at
the dorsal margin; of the three ribs, that nearest
to the hook is the most prominent and the one
adjacent to it Is the weakest but this relationship
may be inverted on other specimens; a
second group of two ribs follows on the hook
and thereafter only single ribs appear; on the
hook the ribs tend to taper acutely toward the
margin of the dorsal area and to broaden on
venter; toward the beginning of the hook the
ribs sometimes develop a weak tendency to
depress along the ventral-central line.
DIAGNOSIS. This species is characterized
by: A) the change of tbe whorl section through
development from circular to subovate, and B)
its peculiar broad ribbing which gave it a wormlike
aspect.
COMMENTS. This species diffeD from
the type species of the genera Ptychoceras and
Euptychoceras as discussed under the genus.
OCCURRENCE. Socota Member. Upper
Aptian.
Pseudoptychoceras gilberti n. sp.,
rMorph I]
1'1.6, Fig. 17.
Paratype. (U.N.C.M.H.N.C.P.Pt. No.4).
One complete hook (?) and a section of
tbe shaft. The dorsum is flattened and rounds
smoothly into the slightly bulging flanks which
in tum grade into a narrowly arched venter.
There are very broad rounded ribs separated by
constriction-like interspace& which cross the
flanks obliquely and project slightly on venter;
both rib and constriction fade out at the margins
of the donal area. The hook has only single
ridge-like rib8'""whicb taper toward, the dorsal
area and are rounded on venter, the adapical
aide of these ridges is steep whereas the adoral
side Is elongated giving that part of the shell the
appearance of consisting of interlocking segments.
NOTE: These fragments have the section of
their shafts more inflated around the
dorsal zone, the ribs are strong and
rounded and cross the venter obliquely,
and the ribs form interlocking rid-
F. ETA YO · SERNA
ges on the living chamber.
OCCURRENCE. Socota Member. Upper
Aptian.
Rif.A::T:iliD A !i(j E m,--
··---am=ilY:_A C O !I!iN EC E !ii
uenus @co1eceros(Hyatt, 1M3.
r;rcocros H'yaft, 19oa·;·p.loo.
•.•• ,. •• ,.,... .,. ••• • •.
. • -.. :.:-• - .. . · . .•. - 4'• .- -. . . . • ..- · .··-:- · ..
TYPE SPECIES. Ammonites nisus d'Orbigny,
mono typic.
"ficw "ros tierrezealmf.- n.sp .
. 6, Fig. 15;exi-Figs. 33Y, 3Z.
Holotype.C-223 (U.N.C.M.H.N.C.P. Ht. N.7)
Paratype. (U.N.C.M.H.N.C.P. Pt. N.5)
A) Up to 10 mm diameter. The fil'Bt whorl
of the phraginocone is inflated and has a whorl
section only slightly higher than wide, evenly
rounded and with a wide ventra] area. On the
specimen studied the internal mold of the fiDt
whorl shows a rounded rib parallelled on each
side by a rather shallow constriction. On the se·
cond whorl the section is ovoid and has a narrower
ventral zone. On the third whorl the flanks
become flattened and the ventral zone fastigate
and slightly shouldered at its margins, the umbi·
Iical wall is short but vertical with a blunt umbilical
rim. The ornament consists of bundles of
falcate pleats, they trend prorsiradiate to weakly
concave from the umbical rim to the boundary
between the adumbilical and middle thirds of
the flank where they bend sharply, fonning cres·
centic adoral concavity and fm ally projecting
on venter. The pleats are stressed and slightly
raised about the involution line where the sharp
acute bend occurs. The space between the plea
is narrower than the pleats themselves.
B) Up to 20 mm diameter. The most im·
portant aspect of the conch at this diameter is
that the umbilicus has not increased its width at
all, in spite of the great increase in the height of
the whorl; the sides are noticeably flattened
and the venter is planifastigate.
The suture line has E/L divided by a lobe
into two branches of which tbe external one is
the widest and it is also bisected; the internal
branch is subdivided into three ramose bran·
ches. The L/U2 has the internal branch larger
than the rest of the saddles; the external lobe is
subsymmetrical.
DIAGNOSIS. This species is characterized
by: A) its ontogenetic development changing
from inflated involute to septicarlnate oxycone;
the internal mold is almost planlfastigate, and
B) iUI strongly falcate Urae and the tendency of
these to become stressed about the centrolateral
,cute bend.
Meuuremental
Holotype
Para type
D Euw
19 2
9 2 ..
H. W D/Euw0h, D/HOfo
11 5 10 57
5 2 22 55
COl\!MENTS. This species can be differen-

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 23
tlated from Aconeceras nisus d'Orbigny (1841,
p.184, pl. 55, Figs. 7, 8, 9; Sarasin 1893, p. 153,
pl. 4-6, Fig. 9a, b, c, Text-Fig. 1, 2) irrespective
of size, mainly by the more massive and rectan­
gular base of E/L in the Colombian species. On
Sara&in's Figs. 2,3 (ib., p.153) and in d'Orbigny's
Fig. 9 of plate 55, the io_temal branch of E/L is
stronger than the exteni81 branch of the same
saddle, but in the Colombian specimens the re·
verse 1s true.
On Aconeceros nisoides (Sarasin) [ 1893,
i.155, pl.4-6, Figs. lOa, b,c, Text-Flg.3; Casey,
961. p. 125, pl.26; Figs. 3-5, Text-Fig. 41a-c],
again the internal branch of E/L is the predo­
minant (see also Fig. 4le, p.127, Casey, op.cit.);
the growth striae in the Colombian species are
more acute than in the French species (see
Casey op.cit., fig. 41c). The specimen figured
by Somay (1955, p.l2, pl.l, Fig.14) has
a juvenlle suture with E/L symmetrically bifid.
Incidentally, immature whorls of the
Colombian species bear constrictions that are
absent on mature whorls;
': ·.
OCCURRENCE. Socota Member. Upper
Aptian.
Family DEPcMOCEATIDAE
Genus
Melchioriie sptit. i923, p.33 -
_., .... ,. ---.. .. ...... , . ·
·
'· . __ ... .... ..
-- ..
IMe Chiorite{ Spath, 1923.
TYPE SPECIES. Ammonites melchioris Tietze,
original designation.
*ehtBrites media Riedel '?
: : ig. 9; Text:Fig. 3Q, 3 R.
1938 Melchiorites emerici Rasp. var. media
· Riedel, 1938, p. 17, pl. 4, Figs. 9 · 11
pl.12, Fig. 7, pl. 14, Fig. 3.
·· 1957 Melchiorites emerici meaius Riedel,
Burgi, p. 134.
1964 Melchiorites emerici medius Riedel,
Etayo-Serna, p. 111.
non 1965 Melchiorites inca (Forbes), Btirgl, in
.. Campbell arid BUrgi, L. C. D. 8393.
1!:1.65 Melchiorites emerici media Riedel,
BUrgi, in Campbell and Btirg L.C.D.
839"3.
l{olotype. Riedel's figured specimen, 1938, pl. 4,
... ·• . . . . .. Fig. 10-11.
!otype.C-127 (U.N.C.M.H.N.C.P.Hy.N.2.).
·,.t'e locality. Utica (Cundinamarca).
.. · · .. .
Two specimens are available, one of them
deformed. The conch is moderately involute· the
section of the whorl is subquadrate, feebly on­
vex tq Oattened and subparallel on adumbilical
halt of.flanks, then slightly converging to the
feebly arched venter; the umbilical wall is short,
vertical, and rounds abruptly Into the flanks. In
both specimens the adapical third of the last
preserved whorl is septate, the remaining part of
the conch represents the living chamber; there
are constrictions which begin at the umbilical
seam, they are falcoid and wide, they describe
an adoral arc on middle of flank and they project
in a strong linguiform fashion on venter.
On the test of the hypotype C-127 there are
faint falcoid sheaves of stressed growth striae
forming thin, flat ribbons that project on venter
paralleUing the constrictions; on the living cham­
ber this ornament is visible also on the internal
mold where the ribs still retain a uniform thickness.
DIAGNOSIS. This species is characterized
by A) Its compressed section of whorl, slightly
taller than wide, and B) its peculiar sheaves of
rm e striae that form low, flat falcoid bands on
test.
Meuu:rementa. D Euw H W D(Euw % -jH%
Hypotype 18 5 7 7 28 38
COMMENTS. The type species of the genus,
"Ammonites melchioris" Tietze (1872, p.
135, pl. 9, Fig. 9a, b, 10) has a higher and
narrower vaulted whorl section than Riedel's
species. Riedel has .discussed other comparable
species.
OCCURRENCE. Unnamed unit above the
Socota Member and below the Capotes Member.
Upper Aptian.
.Me.l£hiorites121Jlmruj n. sp.
PI. 6, Figs. 6, 10; Text-Fig. 3$
Holotype. C-223 (U .N.C.M.H.N.C.P.Ht.N.8).
Paratype. (U.N.C.M.H.N.C.P.Pt.N.6.).
A) Up to 20 mm fC-2001. Whorls slightly
wider than high (at D:l1,H:7, W:9);each whorl
covers approximately half of preceding whorl.
The inner whorls have rather close, narrow but
conspicuous oblique constrictions; on the adapica!
segment of the last preserved whorl of this
specimen the constrictions begin at the umbilical
seam, slant across the umbilical wall, then
bend and widen near the middle of the flank,
and next project forward as a linguiform arc,
that is most narrow at the ventral median line.
The constrictions are preceded adapically by a
rib which starts near the middle of the flank
and on venter it projects in the same fashion as
the constrictions; a very shallow depressed zone
adorally precedes the rib also.
The ornament becomes distinctive with
growth. It consists of fine rounded riblets some
of which begin in a subdued manner on the
umbilical rim and one or two shorter intercalatory
ribs appear about middle of the whorl; the
large ribs are falcoid, all ribs are well developed
on venter. The constrictions trend across the
ribs. There are 8 constrictions on the last pre·
served whorl and 8 riblets on the space between
the two last constrictions; the intercostal dis·
tance is slightly larger than the width of the
ribs. The umbilical wall is short, vertical, it

24 F. ETAYO ·SERNA
rounds abruptly into the convex sides.
B) Up to 30 rmn [C-223]. One incomplete
specimen septated throughout is available. The
early whorls are smooth. The phragmocone is
sculpt .. ued with periodic, widely spaced radial
flared ribs. These prominent ribs begin at the
umbilical margin in a subdued manner; they
trend obliquely on the adumbilical third of the
whorl or form a tenuous adoral concavity. At
the boundaey with the central third of the whorl,
the ribs make a sharp bend and then up to the
ventral zone they fonn an adoral concavity.
Next they cross the venter in a linguiform ado
ral arc; they are emphasized adventrally. The
section of the whorl is subcircular, slightiy wi·
der than high (H: 10m.m; W: llmm), especially
on the internal whorls; the venter is broadly
rounded grading smoothly into the convex
flanks which grade abruptly into the vertical
umbilical wall.
On the internal mold and also observable
on the exterior of the test there is a constriction
just ad oral to the flared rib; a flattened
area develops adapical to it. Between two of
the prominent ribs there are numerous fm e ribs
(up to 10-14 on venter) which are divided into
two types: 1) slightly prominent, low, fine, top
rounded ribs that begin slightly above the urn·
bilical rim, their trend is that of an elongated S,
like the flared ribs, and 2) fine intercala..T)' ribs
. which rise slightly higher on whorl and only rarely
bifurcate from the primary ribs. The inter·
costal space is at least twice as wide as the ribs,
sometimes greater; the umbilical rim is smoot!":;
with growth the bifurcation or trifurcation of
the ribs seem rather common. On the adoral·
most preserved segment the ribs gather in bundles
·fanning a low triangular periumbilical thic·
kenning which extends form the center of the
flank to the umbilical rim but this does not
occur on the preceding whorls.
. DIAGNOSIS. This species is characterized
·
by. A) its subrounded whorl section, B) the in·
, creasing number of fine ribs through the onto·
· geny, and C) by its strong, flaring linguiform
ribs;
Miluurements. D Euw · H w
Holotype - 31 12 7 1
·Paratype 22 7 1 7
D{Euw % D/H %
39 ?
32 ?
. .
COMMENTS,: Both specimens here COfilSi·
dered conspecific have to be compared indepel)
·dently to other species. In regard to the smaller
specimen, the .closest species known to me is the
one figured by Pervinquiere (1907, p. 155, p.
156, Text-Fig. 61, pl. 6, Figs. 21a-b, 22a-c) as
"Puzosia AnglGdei Sayn"; this thick form shows
fine ribs mostly near the constrictions when:as
in my specimens the ribbing is more uniform
and perc.eptible inwards, down to the involution
line; in the latter feature the Colombian species
is more like the holotype (?) figured by Sayn
(1890, p. 173, pL.2, Fig. 13a, b, c); this could
possibly be due to preservation though.
Pervinquiere (ib., p. 156) compared his
specimens to "Puz. Emerici Raspail" though he
remarked on the flattened flanks and the greater
development of the last who;l in the latter.
In regard to the large specimen (holotype},
this is somewhat similar to "Desmoceras akus·
chaense Anthula" as figured by Jacob (1905, p.
402, pl. 12, Fig. 1; =Valdedorsella Brei&troffer,
1947), but the French species is much more in·
volute and its flared ribs have a peculiar splitting
at that point where the Colombian species have
a centro-lateral acute adoral bend. The African
and European species referred to Valdedorsella
by Breistroffer (194 7, p. 60) are much more in·
flated and narrowly umbilicated than the speci·
mens from Colombian here assigned to Melchiorites.
The constrictions on the latter group of
species is Puzosia-like. This interesting Colom·
bian species also resembles Melchiorites media
Riedel, but the latter lacks the discrete ribbing
on the external part of the whorl and its whorl
section is ogival rather than rounded.
OCCURRENCE. Socota Member Upper
Aptian.
Genus · \Valdedorsella)Breistroffer,
1947.
: Valdedorsella Breistrofer, 1947, p. 60. . :
'' --t. -·..,..-p:•• ,,_.._., • ...,,.,.::,•,j,..p...r•'""
-.... ,...-.,., ,.·,· --- ... . ••-· '• •-·· ----...·-
TYPE SPECIES Desmoceras akuschaense An·
tula, origtilal designation •
Valdedoryella f71 colQ.mbia n. sp.
'M:3, Fig. 10; Text-Figs. 3V, 3W. .
Holotype. Santa Ana (U. N. C. M. H. N. C. P. Ht.: '
N.9).
Paratype. Santa "Ana (U.N.C. M. H,. N. C. P. Pt.
N. 7).
A) Up to 35 mm D. [Sta. Anal. 'The section
of the whorls is suboval, inflated. The test
is ornamented with sinous, flared ribs (27 per
whorl), which correspond to prominent ribs on
the internal mold. There is a constriction on
both sides of the ridge on the internal mold,
they follow the trend of the flared ribs but
attenuate on venter. On the test the constric·
tions are indicated by smooth bands parallel to
the ridges. The sulcus immediately adapical to
the flared ribs is usually the most prominent on
the adumbilical half of the whorl side, but the
reverse is true on the adventral half of the
whorl side. Between two of the ·prominent ribs
there are numerous (:up to 8), rounded ribs,
separated by intercostal spaces one and a half as
wide as the ribs. 'These ribs on venter represent
both primary ribs that originate above the umbi·
Iical rim and secondary ribs that arise from the
primary at about the midpoint of the Oanks. At
the same time the frrst pair of ribs immediately
.adoral to constrictions tend to separate therrisel·
ves from the rest which gather to form a low
bundle at the umbilical rim.
B) Up to 60 mm D [Sta. Ana]. The deve·
lopment of the ornament continues similar to
the previosly described stage except that there

ZONA'riON OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 25
seems to be a tendency to decrease the number
of the ribs on venter between the constrictions,
from 8 to 6 or 5. The living chamber has been
preserved as a quarter of a volution.
DIAGNOSIS. This species is characterized
by: A) the decreasing number of the ribs between
contrictions from...S to 5 through growth,
B) the stressed ribs gathered in bundles toward
the umbilical margins, ands C) the inflated
whorl section.
Meuurements
Holotype
Puatype
D Euw
57 22
37 ?
H W DfEuw% D/H %
22a 20a 38 38
? ? 7 7
COMMENTS. The disposition of the
constriction in this species is close to that des·
cribed by Jacob (1905, p. 402, pl. 12, Fig. 1)
for ''Desmocerasakuschaense Anthula" although
in the French species the flare is divided at the
bend at the midpoint of the flank. This species
resembles "Desmoceras " sparsicosta Boese
(1923, p. 107, pl. 7, fig. 1-3) from Mexico; the
latter, however, possesses intermediate ribs that
bifurcate twice at differente levels on flank
(Boese, ibid., p. 107), whereas in the Colombian
species the bifurcation occurs only once;
the ribbing is much more prominent on theMexican
species, which in addition, is less inflated
than the Colombian species.
OCCURRENCE. Socota Member. Upper
Aptian.
== pseu doha plc er a s }.!:1!-oo:_
Pseudohaploceras Hyatt, 1900, p. 570.
TYPE SPECIES. Haploceras liptoviense Zeuschner,
in Uhlig 1883, original
designation.
uf!l!jaeJ ceras leivaense.l}· sp.
P g:-'1 , Text-fig. au, au.
Holotype. VI-10-17 (U. N. C. M. H. N. C. P. Ht.
N. 10).
The inner whorls are apparently smooth.
The section of the second whorl is vaulted.
Flanks diverging from the rather narrow venter,
reach their maximum width near the external
part of the adumbiliclil third of the flank and
then grade abruptly into the vertical umbical
wall. The last whorl has a cross section much
the same but more inflated.
The test of the last preserved whorl is
ivided into seven trapezoidal areas by flared
nbs which begin irregularly on the adumbilical
thir of the flank although the growth lines
project obliquely onto the umbilical wall. The
intercostal distance between flaring ribs increases
toward the aperture; between two of the
fiared major ribs there are from 7 to 9 finer
alcoi ribs which begin as stressed growth
lines. Independently or in bundles (barely
bulgmg), and which become clearly defined just
adumbilical to mid-venter; they are rounded
and are half as wide as Ule intercostal spaces;
some of Ulem widen irregularly on venter. On
the living chamber Ule ribs become very accen·
tuated especially where Uley fonn bundles but
they do not develop real bullae.
DIAGNOSIS. This species in characteri·
zed by: A) its ogival whorl section, B) the in·
creasing width between its flaring ribs or constrictions
through growth, and C) the progressive
stressing of the primary ribs on the flanks.
COMMENTS. There is some resemblance
between this species and "Puzosia Douvillei"
Fallot rFallot, 1920, p. 259, pro. "Puzosia Matherom
d'Orbigny" H. Douville (1916, p. 103,
pl.13, Figs. 1 to 7)'J, especially"in the tendency
of ribs to gather in prominent bundles adumbi·
lically without, however, Conning heavy bullae
as in Uhlige lla (Jacob, 1907). The African spe·
cies shows more discrete and finer ribbing. Mo·
re similar in appearance, however are several of
the specimens figured by Boese from Mexico as
different species of "Desmoceras " in which the
tendency of the ribs to gather in umbilical bundles
is much more accentuated; one of the most
similar species would be "Desmoceras alzatei"
Boese (1923, p. 114, pl. 8, Fig. 15-18) but the
Mexican species has closer, less distinct ribbing
than the Colombian species.
OCCURRENCE. Paja Formation. (Arcillolitas
abigarradas;segment E). Upper Aptian .
· ·-ae-nus __ -- · ·_-r:coae-;c!{.3n.·
g. ;;. _; J
_
TYPE SPECIES. Carloscaceresiceras caceresi n.
sp.
DIAGNOSIS. Moderately evolute conchs,
with low ogival whorl section; the umbilical
wall is vertical and merges abruptly into the
flanks. The ornament consists of sinuous to bi·
concave growth striae gathered in bundles or
weak riblets which sometimes produce on the
internal mold a ribbon-like subdued costation,
particularly visible on venter. There are cons·
trictions preceded by a prominent rounded
swelling visible both on test and the internal
mold but which develop on the adventral
third of the flank only; adorally the constric·
tion is margined by a blunt ridge extending
across the flank down to the umbilical edge, it
is not noticeable on the test. The constrictions
are accentuated progressively with growth,
from almost incospicuos on the early wh·oris to
very wide on the living chamber. The constric·
tions cross normal to the ventral median line.
The apertural border is plain and follows the
path of the growth striae.
The suture line has E shorter than L,
which is deep and very incised.
COMMENTS. . This _
_new _ __genus .. difters
JI(J.ffi_}3_eudanticeras m_i! ... 19_95) because of
its lomr ·mer wider whorl section, its more
evolute whorl and the strengthening of the
internal sculpture during growth. It differs from
Pseudorbulites [Casey , 1961, p.145, ex Breistro·

26 F. ETAYO · SERNA
ffer, 1963, p.74, nom. nudum type species
UhligellD convergens Jacob, 1907, p.29, pl.2,
fig. 25a, b,c} because the latter lacks flanges
bordering tlie constrictions, has narrow and
falcate constrictions and has a funnel-like
umbilicus. From Puzosia (Bayle , 1878) it
diffen in the lack of linguifonn projection of
the constrictions on the venter and the suture
line with only feebly retracted suspensive lobe.
This genus is named in honor of geologist
Carlos Caceres.
Holotype. C - 170 · 20 (U.N.C.M.H.N.C.P.Ht.
N.lll
Paratypes. C· 1 · 1,2,3- (U.N.C.M.H.N.C.P.Pt.
8,9,10).
A) Up to 20 mm (C-13·1,2 ). The first
whorl after the protoconch is subcircular in sc·
tion, the second whorl is slightly higher than
wide but already has a steep umbilical wall; on
the third whorl the vaulted shape of the whorl
section is reached. The test has growth striae
that extend obliquely from the umbilical rim
and describe a feeble concavity on the umbilical
third of the flank; on the central third of the
flank they fonn an adoral arc and on the adven·
tral third of the flank they fonn one acute concavity,
next they project mode!ately on the
• -
venter.
B) Up to 26 mm diameter (C- 13-3]. Up to
this size no special change occurs on the test
ornament except that the umbilicus has already
begun to widen. The growth striae tend to form
irregular bundles which may leave slight bands
or rib-like impressions on the internal mold;
some striae appear more accentuated than others
especially on venter.
C) Up to 50 mm D (C-13- The specimens
are septate; weak elongated S·h e constrictions
appear; the remainder of the conch corresponC:.s
to the living chamber. Approaching the beginning
of the living chamber the constrictions become
progressively more accentuated; the constrictions
are preceded adapically by a flange-like
bulging on the periventral margins and vent.er
only, but the adoral margin of the constrictions
fonn a short vertical ·wall on the internal mold.
Very wide and · slightly arched constrictions tP.nd
to divide the internal mold corresponding to the
living chamber into triangular segments, and on
these there are htdications of tenuous ribs that
cross the venter, they are narrower than the intercostal
spaces and extend down to the umbilical
seam. These ribs correspond to bundles of
growth striae on the test. The living chamber
occupies half the length of a whorl. On venter
there are ridge-like thickenings of the test co·
rresponding to the constrictions on the inter·
nal mold, but the thickenings are restricted to
the venter and are not noticeable on the flanks.
DIAGNOSIS. The same as for the genus.
Meuurement 0 Euw H W Vw O{Euw O{H W{Vw
% % ,Ofo
C- 13• 1 26 6 12 10 6 24 48 50
c- 13· 2 19 4 9 8 4 21 47 50
C- 13· 3 26 6 13 10 5 24 62 50
c- 13- 4 20 4 10 9 4 20 1>0 44
C· 13· 5 17 3 9 7 1 17 52 1
c- 13·12 25 6 13 7 1 24 62 1
c- 13-13 29 7 14 11 6 24 48 45
c- 13·14 18 4 9 8 4 22 60 50
c- 13·1fi 28 7 14 10 6 25 60 60
C- 13·17 29 7 14 10 6 24 48 60
c- 1a-1s 30 6 16 11 6 20 40 1>4
C- 13·19 32 8 16 7 ? 26 50 7
C· 13·20 35 9 17 14 7 26 48 50
C· 13·22 34 9 16 13a 7a 26 47 40
C- 13·23 37 10 17 13 8 27 47 61
C• 13·26 41 12 18 14 9 29 44 64
C· 13·27 42 11 20 16 9 26 47 60
C- 13-28 42 12 20 16 9 28 47 60
C· 13·29 48 13 21 18 11 27 44 60
C- 13-30 48 14 20 17 10 29 41 59
C- 13·33 34 8 16 13 8 23 47 61
C- 13-34 50 17 21 7 1 34 42 ?
C· 13·36 53 17 23 18 9 32 43 50
C- 13·36 68 20 21 ? ? ? 34 7 ?
C- 1 3·37 52 21 18 ·u 18 36 40 60
C·170· 1 20 6 12 8 4 25 60 50
C-1 70· 2 22 6 12 9 5 23 M 56
C-170· 3 30 6 16 10 5 20 53 60
C-170· 4 32 7 16 12 7 22 60 68
C-170· 7 29 7 14 10 6 24 48 60
C-170· 9 41 10 20 15 8 24 48 63
C-170·11 48 14 21 18 9 29 46 50
C-170·12 46 13 20 17 9 29 44 53
C-170·13 46 12 ,20 17 10 26 ' 43 58
C-170·14 44 12 20 16 9 27 45 56
C·170·16 44 15 19 16 8 34 43 60
C-170-16 44 13 19 16 9 29 43 66
C-170·17 46 14 20 17 9 30 43 63
C-170-1 8 64 18 22 18 10 33 40 65
C-170·19 60 14 23 18 12 28 46 65
C-170·20 62 19 26 21 11 30 42 62
C-170·21 5 7 17 - -24 20 11 31 44 56
C-1 7D-22 76 27 29 28 15 36 38 63
C·17D-23 79 31 31 28 13 39 39 46
COMMENTS. Same as for the genus.
A Peruvian species of ammonites descri·
bed by Gabb (1881, p. 268, pl. 37, fig.l, 1r£! as
"A [mmonites Hyatti", has (ibid.) "su ace
smooth, or on y marked by indistinct lines of
growth, which bend forward on the inner margin
of the whorl, slightly backwards. on the
middle, and then fonnard towards the dorsum .. '
Lisson (1937, p. 23) renamed this species "Des-
mocera$_ Hyattum ", and pointed out (ibid p.25)
that it lacks constrictions and ribs. These characteristics
recall those of the genus Carloscaceresiceras;
however the stratigraphic position of
Gabb's species remains undetermined (BenavideS'-Caceres,
1956, p. 439).
OCCURRENCE. Capotes Member Lower
---...
Albian.
.,e.aroscgce!]§Jc!lro maat!lmLn. sp.
Pl. 0. Fig. 5; Text-figs. 4E; 10.

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 27
Holotype. C-13-33 (U. N. C. M. H. N. C. P. Ht.
N.12).
Very similar to the previously described
species, but in the fanner the elements of the
suture line are higher and the saddles are more
finely zigzagged-lncised;"'in the preceding spe­
cies the adumbilical and central thirds of the
flank are Oat, the adventral third of the flank is
slightly beveled. In Car/oscaceresiceras monteroi
n. sp. the flanks are faintly convex and furthermore
they show more indication of ribbing on
the internal mold.
OCCURRENCE. Capotes Member-Lower
Albian.
This species is named in honor of geologist
Juan Montero:
loceresjcerns C? J £hjmuense, (Bena·
V1 es ace res)
Pl. 11, fig. 9; Text-figs. 4J, 4K.
Hypotype. VL.33a. (U.N.C.M.H.N.C.P. Hy. N.3).
1956 Desmoceras chimuense Benavides-Caceres,
p. 438, pl. 41, figs. 5·8.
1964 cf. Desmoceras chimuense Benavides·Ca·
ceres, Etayo-Sema p. 37, fig. 9.
One internal mold in black calcite. The in,
nennost whorl observed is higher than wide in
section, it has flat flanks which round abruptly
into the short but vertical umbilical wall. The
ventral zone is not discernible ; the visible part
of the flanks shows fine growth striae which
form .a shallow arc from the umbilical seam to
the involution line. The last whorl preserved
has flattened sides which feebly diverge from
the evenly arched venter; the section reaches its
m!D4mum width about the umbilical third of
the who.rl where the sides round abruptly into
the yertical umbilical wall. On the surface of
th .. is mold, vague
indications of constrictions are
Present but the exact trend of them can not be
.
aec.u:rately detennined because of the state of
prervation.
M.asurementl D Euw H W D{Euw % D/H %
VL"33;. at 7 19 33 30 25 . 44
.. . COMMENTS. In suture line and whorl
$ection this specimen resembles that described
by BenavidesCaceres as Desmoceras chimuense
Bnavides·Cce s, 1956, p. 43, pl. 41, fig. 5·
8, '!'he _spec1es IS referred tentatively to Carlos·
cQcereslceras ..
. ·. ·.· OCCURRENCE. Upper San Gil Forma·
tion, r.,evel 8. Middle Albian.
[[..:.'f C o rt e zi ceraij--g.: . ... :'
!YP · ·· .· . S . JitIES. Corteziceras cortezi n.g., n.sp.
- ZvJNctfc.ff.r, -l'1f7t
. · · • · . DIAGNOSIS. Cnch evolute, of moderate
siZe, The early whorls are finely striated the
su.,sequent whorls are divided into segments by
flaring ribs and between them accentuated ribs
occur; the latter may bifurcate at different
levels on the flank. The more prolonged the
initial smooth stage, the less strong the ornament
becomes; all the intermediate ribs are
prominent, however. The ribs tend to gather in
bundles which reach the umbilical rim tangentially
but they do not develop any umbilical
tubercles. There are two constrictions especially
noticeable on the internal mold, parallelling
each flaring rib, of these the adapical constric·
tion is accentuated in early ontogentic stages
but tends to weaken with growth to th·e benefit
of the adoral constriction.
COMMENTS. Corteziceras differs from
Uhligella Jacob 1907 (Type species: D. clansayesense
Kilian) because it lacks nodes or swe·
llings on the umbilical margin. It differs from
Zurchere/la Casey (1954, type species: D. zuer·
cheri Jacob) because of the weakness of the rib·
bing and greater involution of the latter.
.
This genus is named in honor of Santiago
Cortez, Colombian paleontologist·
{r;,fL r:z s cortezj,. n. sp.
lfC3-ng.2, Text-1ig. 4C.
Holotype. Santa Ana, A .. P. G. · · . (U.N.C;M..
N.C.P. Ht. N. 13)
? 1938 Uh/igella ziircheri Jacob &Tobl., Riedel,
p.20, pl. 4, figs. 12, 13, pl. 14, f.4.
? 1957 Uhlige lla ziirchen' Jacob 8. Tobler;
Biirgl, p. 135, pl. 8, fig.S.
The conch is discoidal, moderately umbi."
Heated. The inner whods are smooth, they are
covered only by sigmoidal growth striae; the
latter are concave ado rally on the umbilial wall,
trend obliquely on the adumbilical third of the
flank, then tum feebly adapically describing a
weak arc on the central third of the flank. On
the adventral third of the Dank they trend subradially
and describe an adoral concavity and
finally they barely project onto the venter.
Fascicules of growth lines near the middle
of the flanks pass into ribs that become conspi·
cuous on the venter; at 25 mm diameter they
are already recognizeable. Periodically one of
these ribs becomes more prominent, especially
on venter, but it shows the same trend than the
other ribs; such flange-like ribs are represented
on the internal mold by a rib also, but, immediately
adoral to it there is a deep furrow that
runs parallel to the rib but which is represented
on the exterior by a flattened band.
Adapical to the rib is another less deep
sulcus on the internal mold corresponding to a
flattened band similar to the adoral one. Be·
tween two of these prominent ribs there are
usually 5 finer but also stressed ribs of which
those two occupying a more central position
usually extend down to about the adumbilical
third of the flank, whereas the other two join the
latter at about the central third of the flank;
I

28 F. ETA YO - SERNA
this is particularly noticeable on the exterior of
the shell.
The whorl section is higher than wide and
is widest toward the adumbilical margin; the
venter is arched, the umbilical wall is subvertical
and rounds smoothly into the slightly convex
Danks. On the internal mold the ribs do not give
the impression of being as inclined as they are
on the test. The intercostal spaces are twice as
wide as the ribs.
DIAGNOSIS. This species is characterized
by A) the progressive ontogenetic development
of the ornametation on which the stres of the
ribbing accentuates with growth from the ven·
tral third on the early whorl towards the adumbilical
third on later whorls, B) the triangular
segments of the test with four to five ribs on
venter, and C) by its relatively evolute conch.
Meuurementll. D Euw H W E/Euw % D/H%
Sta.Ana.A.P.G.No. 64 20 20 18 40 40
COMMENTS. With the name of" Uhligella
zurcheri Jac. It Tob.'' Riedel described (1938, p.
20, pl. 4, fig. 13, U, pl. 14, fig. 4) a species of
ammonites as having two or three weak ribs
between two prominent ribs, however on the
illustration it is possible to count up to 5 of the
"weak ribs". This is proven by direct observation
of Riedel's original specimen (S.G.N.C.P.
o .OS1). Riedel's specimen came from the same
general area as my specimens and I consider
,them tentatively conspecific.
On the specimen figured by Jacob (1906,
p. 9, pl. 2, fig. 1a, 1b) the more numerous principal
ribs aie slightly sinuous only and the triangular
surfaces they circumscribe have the shape
of a narrow truncated pyramid, whereas in my
specimens, because of the exaggerated inclina·
tion of the principal ribs this surface has the shape
of an inequilateral trapezoid , furthermore the
arrangement of the ribs on Jacob's specimen is
as if the central intercalatory ribs were branching
about the .!Piddle of the flank; the ribbing is
uniformly thin in Jacob's species.
The specimen figured by Biirgl (1957, pl.
8, fig. Sa, Sb) corresponds to Riedel's original
of plate 4, fig. 12, 13, but the picture is only
8{10 of the natural size.
The Mexican "Uhligella" reesidei Hump·
hrey (1949, p. 152, pl. 18, fig. 3,4), is a much
smaller and·flattened species on which the streng·
thening of the ribs occurs earlier than in the Colombian
species;theyshare,however, the strength
of the ribbing and the tendency to produce a
wide umbilicus. Casey's suggestion of generic
status for this species and similar Mexican species
(1949,p. 336; 1961, p.161} has, in my opinion,
good biogeographic support. A similar observation
was made by Boese (1923, p. 109) when
describing his "Desmoceras " from Mexico
(trans): "Among the European forms . . . . all
are distinguished by their lack of prominent
intermediate ribs".
OCCURRENCE. Socota Member. Upper
Aptian.
Corteziceras cortezi n. sp.
fMorph I]
Pl. 3, Fig. 7.
Paratype. (U.N.C.M.H.N.C.P.Pt.ll)
Only one specimen is available. The test is
thick, the section of the whorl is vaulted with
sides diverging from the arched venter and gaining
their maximum width at the umbilical rim.
The early visible whorls are smooth except for
barely perceptible fine growth lines. The last
preserved whorl is completely septate; the orna·
ment on this whorl consists of primary ribs
which gather together about the umbilical rim,
the secondary ribs bifurcate from the primary
ones at about the middle of the flank but the
adoralmost of the secondary ribs may itself bifurcate
at U1e ad ventral third of the flank; these
groups of ribs occur between two prominent ribs;
the latter ribs cross the flanks in an elongate S.
On the internal mold there is a channel like
constriction, twice as wide as the flaring rib
which develops immediately adapical to the latter;
this constriction corresponds either to a
constriction or to a flattened band on the test.
The umbilical margin is rounded and the umbi·
lical wall is subvertical on the last preserved
whorl.
NOTE : This morph is notable for A} its rather
low section, B) the frequent presence
of constriction (9 per whorl ?), C) the
fasciculation of the primary ribs around
the umbilicus which, however, do not
fonn nodes, and D) its quick accentuation
of the ornamentation and short
smooth earlier stage.
Meuurementlr. D Euw H W DJEuw % D/H%
Sta.Ana.A.P.G.No. 41 15 16 14 36 36
COMMENTS. This "morph" bears some
resemblance to "Uhligella reesidei" Humphrey
(1945, p. 153, pl. 18,Fig. 3, 4), but the Mexican
species is more compressed, the adumbilical and
central thirds of the flank are flattened and the
bundles of ribs are not as strong and persistent
as in the Colombian "morph". The Mexican
species has attenuated constrictions which are
parallelled by more strongly developed ridge-like
ribs (: flanges) contrary to the Colombian
"morph". This "morph" differs from the bolo·
type because of its more numerous constrictions
and more irregular branching pattern of the ribs.
OCCURRENCE. Socota Member · Upper
Aptian.
r1ezife latecostata. (Riedel)
WI. , Ftg. 6, Text-Ftg. 4F.
1\
1938 Uhligella latecostata Riedel, p.2J, pl.5,
figs. 1-3.
19f.7 Uhligella latecostata Riedel,Biirgl, p. 135.
'

ZONA'l10N OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 29
1964 Uhllgello latecostlltll Biedei,Etayo-Sema,
p.lll.
1966 Uhligell4 14tecostatlJ RiedeBUrgl ln Btlrgl
and Campbell.
Holotype. Rledel's- l!peeimen
Hypotype. (U.N.C.M.H.N.C.P. Hy. N.4).
Type LocalJty. Hacienda Magdalena, Viota
(Cundlnamarca).
Three tragments of Internal molds of the
umple 0.256 are referred to thla species.
The section of the whorl has an arched venter
which rounds evenly Into the flattened flank:a,
the latter feebly diverge down to the adumbWcal
third of the flank where they round rather
abruptly Into the abort aubvertlcal umbillcal
wall.
The omament consists of periodic constrictions
that are wide, channel-like, begin tangentlal
to the umbilical rim, and near the boun.
dary between the adventral and middle thirds
of the flank they describe an oblique feeble arc
which Is followed on the adventral third by a
shallow adoral concavity that directly cro111ea
the venter. Adorally to the constriction there.la
a rib that becomes very prominent on the venter
but which fades out before reaching the
adunibWcal third of the flank or just extendfJ
Into it.
. Between the two constrictions there are
four visible ribs on venter; they correspond to
the branching of two main ribs, the adapical
one that begins at the umbilical rim, trends
almost radial on the adumbillcal third of the
whorl side, then abruptly bends adapically on
the central third of the flank but on the !ldventral
third it trends radially again; at the "point of
Its first bend a second branch arises and descri­
bes a feebiB concave arc across the flank, and
then across the venter. The second major rib
begins at the same point as the first main fu­
rrow, but it trends obliquely describing a feeble
arc on. the central third of the flank, then It
abruptly forms an adoral concavity and rm ally
it croaaes the venter straight; at the bend, a se­
cond, · alightly flexuous secondary rib branch
peazs.
OCCURRENCE. Beds above the Capotes
.Member and below the Socoti Member. Upper
Aptian.
Cortezicel'll8 (?) n. sp. 7
Pl. 3 fig. 6; Text-Fig. 3 &
!let specimen C -513
. Only
one spectrnen is available. The ada­
plcal portion of the last whorl prese!Ved has
flankS that descend abruptly into the umbilicus
and round progressively towan:ls veneer with
the maximum thlcknesa about the midle of the
flank, . then they converge toward the narrow
venter forming a low ogive . TowiU'd the adapical
en of the last whorl, the section tend3 to round
urufonnly.
On the· venter the teat ha periodically
thickened, rounded and llnguilonn flanges
that extend, progmufvely attenuated, to the·
umbilicus In a falcold manner. The early portion
oi the teat Is covered with tine falcold to biconcave
striae with the external adoral concavity
occupying approximately the central and adventral
thirds oi the flank, and then project onto
the venter; toward . the adapertural thlrd.of the
lut whorl, tine rounded ribs that are slightly
narrower than the Intercostal spaces become
well defined especially on the central and adventral
thirds of the flanks. The specimen Is com- .
pletely septate. ·
NOTE : This species Is characterized by: A) ita
inflated, low ogival whorl section, B)
the tenuous, fine biconcave ribs, and
C) the externally accentuated flanges
which correspond to the adapical ridge
of constrictions on the intemal mold.
M .. .un ment.. D Euw. H W DfEuw"f0 DfH%
c-13 32 a u 13 211 44
COMMENTS. This species resemblesPseudorbulites
convergens (Jacob) (1907, p.29, pl.2,
fig. 26a, b, c) but differs In the position of the
maximum Inbation which is more toward center
of the whorl ln the Colombian species. This species
also shows great resemblance to the inner
whori:J of Corteziceras cortezi n. sp., however
has a relatively more compressed whorl section
and does not show the biconcave growth striae.
·-· - Genus f Pseudosaynell4 )spath, 192· .
""
-
_ -
" ...
' ...... ,..... _., - ·
_ .,.,... ."" .. ,- .. , .
Pseudosaynell4 Spath, 1923, p. 66.
· · · -- ·
-
· ·· · .
- ·
-
-
··-
· ··· - ·
TYPE SPECIES. Ammonites bicuroatus
Michelin, original daslgnntion.
eyeudosgnea rafiml!lli n. sp.
.3, Frg; 1; ext- J.g. 4N, 4.0.
P
Holotype. SV.-28 (U.N.C.M.H.N.C.P.Ht.N.14).
Paratype. (U.N.C.M.H.N.C.P.Pt.N.12)
Type locality. Lorna San Vicente, Villa de Leiva
(Boyaca).
Description of holotype. The. conch is in·
volul"e discoidal, with sharp venter; the section
of the ' whorl is lanceolate: the maximum width
is on the flattened peri-umbilical region from
which the flanks slope gently up to the sharp
venter- the umbilical rim is blunt, the umbilical
wall is' almost vertical, it changes its inclination
at depth; when the test is preserved the umbilical
rim appears acute.
On a small piece of test preserved around
the umbilicus occur very rm e growth striae. On
the internal mold are low rounded ribs that begin
faintly near the umbilical m trend
radially on the smooth adumblllcal third or the
flank, make an acute bend on part of the central
third and then describe a wide, cre9Centlc adoral
concavity and project sligtly onto the venter.
From the central bend up to the beginning
of the sharp venter the ribs become broad, low
-

30 F. ETAYO ·SERNA
and bifurcate; interc$tory bifurcating ribs also
appear. The distance between the branches of
the wne rib is narrow, but the distance be·
tween each two couples of ribs is usually wider
than a single rib. The ribs converge toward the
umbilical rim; they crosa the acute venter as
fiat, low belts.
One quarter of the last preserved whorl
corresponds to the living chamber. Towards the
end of the phragmocone the external ornament
attenuates but it Is strengthened on the living
chamber. The acute venter is beaded by the
crossing of the Battened ribs; on the internal
mold there are wide constrictions which follow
the trend of the ribs.
DIAGNOSIS. This spedes is chlll"&cteri·
zed by: A) its disk-like appeaJence combined
with the sigmoidal bifurcating ribs, and E) the
change In stress of its ornament during growth.
Meumementa. D Euw H W E/Euw'% DfH"'o
SV ·28 87 8 37 177 1 2 66
La • Ye 24 4 11 1 n 64
c . 223:1: 27 7 7 7 7 7
COMMENTS. A comparable species was
described by Imlay (1944, p.278, tex-fig. 2-4,
plates 42,43); but from the Ulustrations ofPseZl·
dosaynella (i mbriata Imlay, the Colombian spe·
eles has more sigmoidal and leas regularly spaced
ribs; furthennore, the holotype of his species
shows a definite change In the ornamentation in
the latter stage of the ontogeny; likewise the su·
ture line of the Colombian species hu L divided
by a massive tnushroom-likc satldle that with
growth renders this lobe bifid, but this lobe is
ln comparison slim, moss..J.ike in Imlay's species
(see fig. 4d, p.279); it must be pointed out that
the diameters are not similar, however, the Co·
lombian species seems to be smaller altogether.
Pseudosaynella walcotti (Hill) [1888, p.
128, pl. 1, fig.1; Scott, 1940, p.995, pl.56, fig.
1,2] Is a more evolute species and seems to have
leas numerous ribs, but these are stronger
throughout than on the Colombian species.
Of the European species described by
Sarasln (1893), PseudosayneUa bicuroata (Mi·
chelln) shows a slm.Uarlty In the type of ribbing,
but the Lower Aptian French species has its
Danks more fiattened; the suture line at firr.t
alght looks similar, however at similar diameter
the French species has a more massive E/L
saddle. Collet (1.22, p.17) recorded the French
species from Venezuela, but this record hss
been questioned by Casey (1961, p.172).
OCCURRENCE. Socot.i Member. Upper
Aptian. This species is named In honor of Dr.
Ralph Imlay.
Family P ACHYDISCIDAE
- e iiui l "" mwlceras )Spa'fll; 19 39
Lewesiceras Spath, 1939, p. 296.
TYPE SPECIES. Ammonites Peramplua J.
Sowerby, original designation.
M.lJ.l#t;MQ!_f[lllmli n. sp.
.. Pl.T3";"fig.. 4D.
Holotype. C·310 (U.N.C.M.H.N.C.P.Ht.N.15).
Paratype. C-310 (U.N.C.M.H.N.C.P.Pt.N.13 ).
Description, largely after C-310. The
conch is moderately evolute; on the penultlma·
te whorl and the adapical portion of the last
whorl the ornament consists of widely spaced
fianges or ridges which begin at the umbilical
rim and trend radially up to a point near center
of the flank from which point they trend pror·
siradiate and crosa the venter forming an acute
chevron-like projection; this ridge is paralleled
adapically by a aha Dow constriction which
reaches the umbilical margin; the second,
deeper but narrower constriction pamllels the
ridge ado rally, it fades out near the adumbilical
third of the flank. A leu prominent ridge rima
thiG second constriction.
Between each two adjacent principal
ridges there is a large blunt bullate umbilical
swelling; on the adapical third of the length of
the last preserved whorl this swelling gives rise
to a low rib which dies out about the middle of
the flank or ontlnues almost imperceptibly
across the venter. On the adoral half of the
whorl however, this tubercle gives rise to one or
two rounded and prominent n'b c which describe
an are on the flanks and projecb; onto venter in
the same manner as the constriction. One
intercalary rib which does not reach the umblll·
cus may occur.
The intercostal spaces are wider than the
ribs, they are flattened and shallow between the
ribs which arise from the adumbilical tubercles
but narrower and deep near the constrictions.
The section of the whorl is low, ogtval to
renifonn, the umbilical rim rounds abruptly
into the vertical wall; there are seven prominent
umbillcal tubercles on the last whorl.
DIAGNOSIS. This species is characterized
by: A) the long enduring stage with constrictions
and intervening umbilical tubercles, B) the
pairs of rlbs i!Iising from the umbilical tubercles
later in the ontogeny. Presumably only the ju·
venlle stages are known as yet.
Mtuureruenta.
C·310
C· 310
D Euw H
211 .-11 9
14 li li
w D/Euw% D/H"k
11 "" 36
7 36 36
COMMENTS. In the illustrated species of
LewesicerG 1n the "Treatise" {Wright, 1957,
L-378, fig. 494, la-1b) the principal ribs bonn·
ding the constrictions bear prominent tubercles·
but•the intercalary ribs appears to begin on the
venter and advanCE toward the umbUlcus with·
out any tubercles, completely the reverse o! tbe
Colombian species. Houaa {1965) ball diacuased
at length the problems wlth respect to the type
specie& of IK.wesiceras.

'1\lronian.
ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 31
OCCURRENCE. La Frontera Fonnatlon.
This speciE!& is named In honor of the
geologist Carlos tJ1loa, Instituto Nacional de In·
vestlgaciones Geologico·Mlneras.
... . _
FamilY HEIRATIDAE
,, ! Genus -[Oc fJier# t""ilfof'iruPre!· ·
' mer, 3.
__ .:...:_.,.., •• - . _
.:.:..:_;;>:(.·'-"-"'""""'"' .. .,,., ... ,..,... .... . ......... .. _--:;;r. ... .... ..,. .. .. .. . .-.. ,, .... __ _
Trochleiceras 'Fallot and Termier,1923, p. 74.
TYPE SPECIES. Trochleiceras balearense Fa­
Dot and Tennier, monotypy.
h jc\(7ihce ftil .iUlivW,i n.sp.
I. , _g. , ext· g. f, .
Holotype. C-215·1 (U.N.C.M.H.N.C.P.Ht.N.16}.
Paratype. C-215-2 (U.N.C.M.H.N.C.P. Pt. N.14).
Small, relatively evolute conchs (C-215·1,2).
They have a well defined ventral median groove,
paralleled by rounded ridges, In a pulley fashion.
The initial whorls of the phragmocone are
smooth, covered only by sinuous lirae which
trend as an elongated s with stress on the exter·
nal concavity. The lirae cross the venter nonnally
to the ventral median line. Bundles of striae
form periodic narrow, low ribs which now and
then are raised.
On the living chamber and adjoining part
of the phragmocone, compact bundles of lirae
form a kind of stem on the inner half of the
whorls, about middle of the flank this stem
splits into five rm e, rounded to flattened riblets
that extend to the ventral median line. The
ridges that parallel the ventral median grove
appear minutely denticulate because of inter·
section with the riblets. One tubercle-like
outgrowth on the right side of the holtype is
interpreted as a adventitious growth to cover an
extraneous object.
DIAGNOSIS. This species is characterized
by: A) Its small conch, B) its rounded subrectangular
section, and C) the change in ornament
through growth, showing only sporadically
stressed lirae on the early whorls, and later by
riblets issued in groups of five from an adumbi·
lical principal stem.
Meuurement.. D Euw H W DJEuw% D/H%
C·21&·1 14 6 6 6 . 43 43
COMMENTS. This species can be diffe·
rentiated from the type species of the genus:
Trochleiceras balearense Fallot and Termier
(see Fallot and Tennier, 1923, p.74, pl. 6, figs.
7-9, text-fig. 32; Collignon, Magneticerc.s magneti
C., 1950, p.48, p1.6, figs. 1, 1a, 1b text­
g.4;Wiedmann, 1962, p.323, pl.18, fig. 2, text­
ug. 3J, because the species from the Balearics
d not show any change in the ornamentation
du f!ng ontogen r, and only prominent single
"pnmary riblets ' occur up to the living cham·
ber.
OCCURRENCE. Lower Albian.
This species is named in honor of Professor
Manuel Juiivert.
no/i S ub gJl \
... -a- ma_..p
....
o_ft_a_ic_e_ras__,) n. subg.
-= Tru diflv:wo . .')
TYPE SPECIES. Trochleiceras (Jaumaportai·
ceras), ho(fste t.W,n :n. sp.
DIAGNOSIS. Jaumaportaiceras differs
from Trochleiceras by the absence of a ventral
sulcus or only a very weak indication of it on
the inner whorls, by the presence of ventral
bullae, and by a more lacerate suture llne.
This subgenus is named in honor of
Professor Jauma de Porta.
Troch$ras (Jauma,eortaiceraf!.2.
Jj07fffeJt.ifii. sp.-
PI.10, fig. 4; Text-figs. 4G, 4H, 4L.
Holotype. C-215·5 (U.N.C.M.H.N.C.P.Ht.N17).
Paratype. C-215· (U.N.C.M.H.N.C,P.Pt. N15, 16,
17).
A) Up to 15 mm D [C-215·3,4]. The
conch is small, flattened, evolute; the section
of the whorl is rounded subquadrate; the umbi·
lical wall is vertical and rounds evenly into the
flattened to slightly convex flanks, which in
tum merge smoothly into the flattened venter.
On the adapical segment of the specimen
studied (mostly decorticated), a shallow broad
groove is present on the internal mold. At this
stage of development, when the test is preser·
ved it appears smooth, covered only by rme
growth striae, occassionally one of them is more
prominent. The surface of the shell has low
broad undulations.
The living chamber occupies half a
whorl, and whose beginning in this case
is marked by the close approximation of the
last two sutures which earlier in the phragmocone
are distant from each other. Low
:ounded ribs are developed irregularly on the .
living chamber; they flatten on the venter and
form transversely rounded tubercles on each
ventral margin. Where the shell is preserved
(C-215-4), it shows broad, raised bundles of
lime separated by narrower but well defined
intercostal spaces; theses correspond to the
bulges on the internal mold.
B) Up to 20 mm D [C-215·51. At the dia·
meter of the holotype, the intemaf mold of the
living chamber shows relatively accentuated ven·
trai bullae on conspicuous rounded ribs; the latter
begin on the external part of the umbilical
wall and trend prorsiradiately on the adumblli·
cal third of the Oank, then they abruptly chan·
ge trend to radially or slightly inclined adapica·
fly, they then describe a narrow concave arc on
the adventral third of the flank; they cross
normal to the ventral median line; a few of the
ribs are feebly depressed on mid-venter; the
principal ribs bifurcate twice: first about the
boundary between the adumbilical and central

32 F. ETA YO · SERNA
thirds of the flank where a subtriangular thick·
ening is usually fanned, and second on the ad·
ventral third where no swelling is fanned; the
adoral branch is usually , though not alway£ the
strongest one. The strength of the ribs is not
uniform and the distance between them likewi·
se varies. Adorally to the principal ribs are depreBSed
bands that follow the trend of the
ribs.
During growth the whorl section changes
from subrenifonn to subquadrate with slightly
arched venter, likewise the innennost whorls
are smooth but bear broad flexuous swellings;
in the later stages of growth, and mostly on the
living chamber the secondary ribs branch from
primary ones at different levels. There is a
feeble ventral sulcus on the innennost whorls
which disappears or is very faint on later stages
of growth; appearance of ventral, rounded
bullae-fonn tubercles seem to characterize the
beginning of the adult stage.
The conch appears to consist of in terloc·
king segments;- Now and then the primary ribs
(?) on the inner whorls may be raised as thin
flanges which begin slightly above the umbilical
margin and attain their maximun flaring at the
middle ct' the tlank; parallel and adapical to
them, a wide shallow constriction develops.
DIAGNOSIS. The characteristics of the
species are the same as for the subgenus. The
variation of the morphologic characteristics is
significant: the ribs mny vary in strength, likewise
the width and depth of the constrictions
are variable but not their .;hape; on same phragmocone
both raised and low ribs may develop;
some ribs are broad and low and arise in pairs
from the periventral margin.
Meuuzemente D Euw H W DfEuw% D/H%
C-211)-3 13 II 6 I) 38 38
0·210-4 16 6 6 8 37 37
0·2111•6 22 10 8 8 411 38
C-216 20 ll 7 7 46 36
C·2l6·7 16 7 6 6 44 37
C·21fi-8 16 7 6 6 47 40
C·2lli-ll 16 7 6 6 44 37
C·2l !o·10 13 7 7 ? 1 1
0·216·12''18 7 8 6 44 37
COMMENTS. Trochleiceras ambanjabense
Collignon (1962, p. 37, pl. 130, fig. 985)
from the Upper Aptian (Gargasian) of Madagascar
at equiv&lent diameters (approx. 9 mrn),
lacks the development of the periventral bullae,
it has a more accentuated, even thoutb weak,
ventral mediari groove, the section of the whorl
is subrectangular rather than subquadrangular
aa in the Colombian sp.ecies, furtherm ore
instead of low broad ribs on the early whorls,
the Madaga.o;can species has numerous rm e rl·
blets. The Colombian species diffen from the
type species of the genus by the type of ribbing,
more complicated suture line and nearly absent
ventral groove.
OCCURRENCE. Lower Albian.
This species is named in honor of Professor
Robert Hoffstetter.
Chel o niceras Hyatt, 1903, footnote p. 101
TYPE SPECIES. Ammonites comuelianus d'Or·
• bigny subsequent designation,
I.C.Z.N., opinion 428, 1956.
Subgenus {Epichelonicen!JCasey, 1954.
Epicheloniceras Casey, 1954, p. 113
TYPE SPECIES. Douvilleiceras tschemyschewi
Sinzow, original designation.
eloniceras (Epichel,gTJicets§)
a l!!i n. sp.
H
'":; Tg . ;Text-Fig. 4W.
1968 Cheloniceras aff. Ch. juv. ex. aff. comue­
-lianum d'Orb, Riedel, Etayo-Sema 1968,
Fig. 3, Table I.
Holotype. VL12·2 (U.N.C.M.H.N,C.P. Ht. N.18)
One slightly defonned internal mold is at
hand. The adapical portion of the last preserved
whorl has prominent low rounded primary ribs
which begin near the umbilical seam; they bear
a tiny spinifonn tubercle at the umbilical rim,
and on middle of the flank a very prominent
spinose tubercle at which point the primary rib
trifurcates, the branches cross the venter, slightly
depressed at the median line and fonn rounded
shoulders; on the venter the ribs bend slightly
forward in a broad a.c; of the three branches
the median one tends to be the most prominent;
bet.ween two tuberculate ribs there are two in·
tercalary ribs of which the adapical one begins
at the middle or the flank as if bifurcating from
the subsequent tubercle. A succession of closely
spaced trifurcating ribs follows the preceeding.
Two intercalary ribs reappear about two thirds
of length of the last whorl.
Of the trifurcating ribs only the central
and adapical branches are depressed on venter,
they are nearly equally strong, and are more
prominent than the other ribs. The intercostal
spaCPII vary from narrower to as wide as the ribs
on venter; on the flanks they are deep and
channeled. The large lateral spinifonn tubercles
are pointed adapically, whereas the periumbUI·
cal ones are mammiform. Tne section of the
whorl at the apertural end of this specimen is
inflated renifonn. The conch has 37 ribs on the
venter of the last preserved whorl.
DIAGNOSIS. This species is characterized
by: A) its highly developed lateral tubercles
•from which ribs trifurcate, B) its thick renlfonn
intercostal whorl section, and C) the sporadic
occurrence of intercalary ribs.
"•";,,
Meuuremenu. D Euw H W DfEuw% D!H"k
VI-u-2 s7 13 a a 31> 40

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 33
COMMENTS. This species resembles the
inner whoda of Cheloniceraa (E.) debile Casey
(1962, p. 244, pl. 37, r.a, 7, Text· Fig. 85, 86b
and especially ftgums 86a. 86b) but on the
EugUah species the central one of the branching
ribs Is the 1trongest, turthennore It has "groups
of tblee to four intermediary ribs at 20 mm
diameter ,. (Casey, ibid..,p. 244) whereu in the
Colombian species the intermediary ribs ue
almost abeaent.
Them Is also a resemblance between the
Colombian specimen and the lectotype of the
type species of the subgenus (Sinzow, 1906, pl.
2 Figs. lla-c; reproduced in Casey, 1962, p.
2S7, Text-Fig. 82a, b, c); on the Russian fonn
the ventral median sulcus Is deep and the ven·
tra1 tubercles prominent, opposite to the sltua·
tlon the Colombian species.
OCCURRENCE. Paja Fonnation (Arcillo·
Utu abigarradu, segment E), and base of Ar·
cllloUtu con nOdulos huecos. Upper Aptian.
· · This SJ!ecies is named in honor of Mrs. El·
vira de Borru, of Villa de Leiva.
. Cheloniceras (Ef!.ic!JonJ2e.L camachoi
n. ap.
PI. 2, Fig. 3; Text-Fig. 4T.
1928 Cheloniceras stoliczkanum Gabb,
Buse, p.141, pl.S, Fig. 2. Text-Fig.18.
non 1936 Ch.[eloniceras] Stoliczkanum Gabb,
'
Basse, p. 88.
'l 1936 Cheloniceras ct. Stoliczkanum Gabb
sp. em. Basse, Breistroffer, p. 156.
1938 Cheloniceras stoliczkanum Gabb, An·
derson, P..· 176, pars., only reference
to Basse s illustrated specimen.
1964 Cheloniceras stoliczkanum (Gabb ),
Etayo-Sema, pars., p. 118.
1968 Cheloniceras (Epicheloniceras)stoliczkanum
sensu Basse (non Gabb ), Eta·
yo-8ema, p.28, Fig. 3, Table I.
1970 Cheloniceras (Epich. [ eloniceras V sto·
liczkanum, Wiedmann, p. 484, ex re·
view of Etayo-Sema's 1968 paper.
H olotype. (U.N.C.M.H.N.C.P.Ht.N.19).
. .
Paratype. (U.N.C.M.H.N.C.P.Pt.N.18).
The adapical portion of the last preserved
whod on the holotype (VI-10-17) shows strong
ular ribs which bear a tiny mammtfcnn tu·
bercle at the umbilical margin, a conical tuber·
cle abot the middle of the flank and a promi·
nent triangular transversely elongated :reriven­
tral tubercle; on venter the intercostal :iistance
1
1
• 1 more than twice the width of the ribs but it is
..·
. • th. an
.
. two times on the flanks; in gener 1 the
..&tercostal spaces Qre shallow. The ribs are tnick
an.d rounded.
Between two prominent ribs a nearly
imperceptible Intercalary rib appean, tt Ia
feebly depressed along the ventral median line;
with the tncreuing size the strength of both
ribs and tuberculation rapidly increases, and
approaching the preserved apertural region the
Intercostal spaces are very deep and channel
fonn; at this stage of growth the Intercalary rib
approximates to the periumbUlcal tubercle of
the preceding rib u if arising from t. ·
The periventral tubercles give the impression
of being slightly bent posteriorly. There
are 18 well defined ribs on the last whorl. The
Jatenl tubercles were long and spinose as shown
by depressions on the umbilical wall of the
holotype and the paratype.
DIAGNOSIS. This species is characterized
by: A) the rapid on to genetic strengthening of Ita
ornament contemporaneously with a slow in·
crease of the umbilical diameter, B) ita subrectangular
intercostal whorl section, with greatest
width about the umbilical rim', and C) the regular
occurence of only one intercalary rib appearing
near the umbilical rim .
Meuuremenw. D Euw H W DfEuw % DJH %
VI · 10 • 17 47 21 19 28 411· 40
T.I.P. GuaduQ 61 27 ? ? . 44 1
COMMENTS. This species differs fonn
Cheloniceras stoliczkanum (Gabb )(1869) by not
having the very depre!l&ed whorl section during
ita development and the width-length ratio not
remaining the same throughout as on the bolo·
type of the California species (Acad. Nat. Sci.
Phil., no. 4 786). The ventral nodes on Gabb's
species are broadly rounded, lobe-like, but in
the Colombian species their height is greater
than their width (in correlation with the com·
pression of the section?); the periumbilical tu·
bercles are represented by feeble bullae through
the ontogeny on Gabb's species but they are co
nical and prominent early in the ontogeny of
the Colombian species.
OCCURRENCE. Socota Member. Upper
Aptian. Paja Fonnation (Arcillolitu ablgarradas,
Segment E). Upper Aptian.
This species Is named in honor of geologist
Ricardo Camacho.
1906 Douuilleiceras Stoliczkanum, Gabb, R.
Douville, p. 145 (pars), only pl. 1, Fig. 1,
la.
1925 Douuilleicera.s AmazonarumBurckhardt,
p. 26.
1938 Douvilleiceras stoliczkanum Gabb, Anderson,
p. 176, p.
Holotype. Specimen figured in Douville's paper;
see synonym.

34 F. ETA YO · SERNA
Hypotype. (U.N.C.M.H.N.C.P. Hy. N.5).
Type locality. "Vallee des Amazones .. [sic], un·
known.
Descn· tion after the only specimen avai·
lable [C-514 . This is a moderately evolute species;
the oral portion of the penultimate
whorl is characterized by widely separated, rela·
tively thin primary ribs three to four times na·
rrower than tlle intercostal spaces; they bear a
mammtfonn tubercle at the umbilical rim, and
a prominent spine at center of the flank. On the
adapicai portion of the last preserved whorl, the
ribs appear to be extended towards the umbill·
cal seam, with a feeble adoral concave arc; on
the inner flank the ribs are nearly radial but on
the adventral half of the flank and on venter
they swing slightly forward producing a wide
adoral arc; the growth lines are rme raised
threads which sometimes gather in bundles and
resemble intercalary ribs but no true intercalary
ribs are present. All ribs are depreued along the
ventral median line and on both sides of it pro
minent crest like tubercles are developed. On
the adoral portion of the last whorl the ribs
are only slightly promiradiate. No living cham·
ber is preserved; up to the anterionnost part of
the preserved conch it is septate. The whorl sec·
tion at this point ia inflated, rentfonn, it has an
Inclined J:llbilical wall which rounds &mootbly
into the flanks.
DIAGNOSIS. This species is characterized
by: A) its sparse ribbing with only primary ribs
or sporadic, weak intercalary ribs that disappear
before reaching the umbilical rim, and B) its re·
nifonn whorl &ectlon.
MeUUftlmenta. D Euw H W D/Euw % D/H%
C-614 80 30 20 83 ISO 33
COMMENTS. This is a peculiar species not
easily comparable to any described specie&
known to me; it is most aimllar to "Douuilleice·
ras Martini d'Orb." as described by Sinzow
(1907, p. 171, pl. 2, especially fig. 13a, 13b)
but on the Russian species the intercalary ribs
are common and at simllar dlamete:n when
rlbbinll: is attenuated in the Russian species the
o_p pOSlte seema true for the Colombian Wton.
The generic •ignment is questioned because of
the projection of the ribs onto venter on the
Jut whorl.
OC9URRENCE. Socota Member. Upper
Aptian.
Chlon f&12.f!eloni£erus
r _o'SaQL: n. sp.
PI.2, Fgs. 9·10; Text-Figs. 4R, 48; 11.
Holotype. C·223 (U.N.C.M.H.N.C.P.Ht. N.20).
Paratype. C-223 (U. N. C. M. H. N. C. P. Pt.
N.19, 20, 21).
A) Up to 25 mm D [ C-223·11. The umbi·
liens is deep· and wide; on· the two im t observa·
ble whorls the sculpture can not be clearly dla·
cemed but at the beglnlng of the third whorl
(4th of the phragmocone?), very prominent
elongated spinose tubercles develop on the mid·
die of the flank (= along the involution line),
they arise from low wide ribs which extend
toward the umbilical rim. On the fourth or last
preserved whorl of this specimen very slight
mammiform tubercles develop at the periumbi·
lical inception of the ribs; at the same time on
both sides of the ventral median line, rounded
to acute swellings are developed. Although the
ribs tend to fonn a wide concave arc on the
fianks and to project weakly onto the venter
they also tend to widen on the adumbilical half
of the whorl as if forming an adoral arc 1 at the
same time they tend to split longituainally.
Along the ventral median Une the ribs are de·
pressed; sporadically there is an intercalary rib
which differs from the primary ribs only in its
lesser strength.
The whorl section is subcompressed to
subpoligonal: the umbilical wall is inclined, it
merges smoothly into the slightly convex
adumbllieal half of the flank, the adventral half
of tl1e flank converges and rounds into the flatte·
ned venter.
B) Up to 35 nun D [C-223-2). The earliest
part of the last whorl of this specimen is like
· the late part of the preceding specimen. The ornament
continues developping _ in a similar. way
except that one or two folds (In tercalatory
ribs?) without tubercles appear between two
primary ribs. The periumbilical tubercles conti·
nue inconspicuous but the ventral tubercles
tend to acoontuate; the ribs tend to extend to
the umbilical seam fanning and acute adoral
concavity.
C) Up to 50 mm D [C-223·11]. At the
beginning of the last whorl in this specunen the
distance between the centrolateral and periven·
tral tubercles progreuively increases. At this
stage the intercalary ribs are well defined and
characterized by lack of periumbilical or lateral
tubercles, they have only periventral tubercles;
this intercalary rib appears near the preceding
primary and approaches it near the umbUlcal
margin. The last two ribs of this specimen chan·
ge their strong lateral tubercles into tiny spines.
'Ibe Intercostal whorl section ilaubrectangular,
it has an oblique umblllcal wall which tends to
become vertical toward the umbilical seam. The
ventral zone is nattened. Near the aperture the
ribs give the lmpression of slightly curved clubs.
D) Up to 75 mm D (C-223]. The oma·
ment is u on the preceding specimen; the living
chamber represents two thl.rda of the last whorl;
the principal morphological features are the
progresaive weakening of the tubercles, especla·
lly the centroiateral and ventrolateral onea,
which cwaes the ribs to loose their ventral
median depression. 'Ibe adaperturalmoat whorl
section is a slightJ.y depresaed dome.
.
DIAGNOSIS. Thia apeclea is characterized
by: A) the ontogenetic development of the no
des whose strength lncreaaes from mammiform
adumbilica! ones to the pertventral comute tu·
!.'lerdes which in intennediate stages of growth

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 35
are very prominent but fade out on the adult
earlier than the lateral and adumbilical, B) its
simple, well separated club-shaped ribs, and C)
its subrectangular, dome-like whorl section.
Measurement. D Euw li w DfEuw%D{HO/o!"o. R.
c23·t 25 14 9 1'3· 66 36 ·J0(1/2)
C·223•2 36 16 13 18 44 16
c-22a-3 33 14 15 19 42
43 19
46 19
36
.
C-223-4 12 13 14 40 30
C·223·1i 41 19 16 20 46 19
C·223.0 32 14 12 16 40 38
39
9(1/2)
C·223·7 41 20 16 ? 48 39 19
C·223-8 7 7 7 7 ? 7 9(1/2)
C-223·9 1 1 7 1 ? 7 9(1/2)
43
C·223·10 19 16 21 44 39 22
C·223·11 63 25 20 26 47 38 19
C-223·12 47 21 19 22 44 40 ?
c-223·13 --33 22 20 25 41 38 10(1/2)
C·223·1 4 1 1 ? ? ? ? 10(1/2)
(·223·15 57 26 21 27
44
46 20 37
C:·223·16 73 32 25 36 34 23
COMMENTS. This species is similar to
Cheloniceras (Ep icheloniceros) subnodosocos·
ta tum (Sinzow) [1907, p. 175, text- fig_. 4-5,
pl. 2, figs. 1 • 8, especially plate 2 fig. 8 j, but
on the Russian species is a secondary rib which
arises from the lateral tubercles and a single in·
tercalary also occurs, a charateristic that does
not occur on the Colombian species; the latter
also seems to attain a larger size than Sinzow's
species. From the preceding table it is clear that
the number of ribs is very constant in the Co·
lombian species, contrary to the Russian species
in which this number is variable. The record of
Sinzow's species in the Villa de Leiva by Biirgl
(1954, p. 16) and quoted by myself (1968, p.
28), is now considered doubtful.
OCCURRENCE. Socota Member. Upper
Aptian.
This species is named in honor of Profe·
ssor Carlos E. Acosta, Department of Geocien·
cias, Universidad Nacional. Bogota.
Chelonicera (EpJcheloniceras) jimenqL
n. sp.
Pl. 2, Fig. 8; Text-Fig. 4X.
Holotype. C-514 (U.N.C.M.H.N.C.P.Ht.N.21).
Paratype. C-514 (U.N.C.M.H.N.C.P.Pt.N.22,23)
A) Up to 15 mm D [C-514 ]. The whorl
section is renifonn. The sculpture consists of
veey faint ribs, slmost plaits, prorsiradiate, they
describe a wide arc on the venter; the adapical
half of the last whorl on this specimen has the
shell preserved; the ornament visible on it :s low,
belt-like ribs ventrally arched and separated by
wide intercostal spaces which are covered with
growth striae; fine flat ribs may interpose ado·
rally. The whorl section is a smooth arc. On the
adoral half of the last whorl of this srecimen,
inconspicuous mammiform prominences begin
to form on the ribs at the middle of the flanks.
:rhe ribs begin at the umbilical rim but some
mtercalary ribs begin on the adumbilical third
of the flank. The umbilicus is deep.
B) Up to 21 mm (C· 5141. The ribs have a
tendency to develop a second, faint, radially
elongated tubercle at the periumbilical margin;
on the venter they te··tQ.l\*tpress along the
median line and to raise' sl}gJ:ill!:on both sides;
the ribs are very fine, thread-like to moderately
strong, feebly sigmoidal on the flank and projec·
ted as a wide arc on venter. ..
C) Up to 30 mm D [C-514). The periven·
trai and lateral tubercles accentuate for a short
distance and then soon fade out. Sporadically
some intercalary ribs detach from a node on a
primary at the middle of the flank or from its
periumbilical region. There is a tendency toward
an alternation of a secondary rib between two
primary ones; at the anteriormost observed part
the whorl section is subquadrate.
D) Up to 60 mm D [C-5141. Only half of
a specimen is available on which four whorls
can be observed. The umbilicus is deep, funnel
shaped. On the second internal whorl there are
low ribs which disappear before the umbilical
rim; the umbilical wall is subvertical, high, it
rounds smoothly into the convex sides. On the
third whorl the ribs are rounded imd extend
as sharp ridges to the umbilical" seam, they des·
cribe an adoral ccncavity on the umbilical wall
and part of the adumbilical third of the flank
but on the remainder of the flank they describe
an adoral arc; at this stage of development the
intercostal spaces are two to four times as wide
as the ribs when no intercalary -ribs are develo·
ped.
Intercalary ribs are rare. On the last whorl
the ribs are thread-like, acu te and conspicuous;
they begin near the middle of the umbilical wall
and trend rursiradiate to the umbilical rim where
they bend abruptly, then they trend nearly stra·
ight or in a feeble forward arc on the central
third of the flank, then they cross the venter .
straight or bent forward. On both sides of ven·
ter the ribs raise in a feeble bullae and the me·
median ventral region appears slightly excava·
ted. The intercostal spaces are very wide, cha·
nne!-like, three to five times as wide as the ribs.
The whorl section is nearly rectangular with
rounded periventral margins, flattened venr
and moderately oblique umbilical wall.
DIAGNOSIS. This species is characterized
by: A) the transitory development of the lateral
tubercles, B) the numerous fine, acute ribs on
the adult whorls with nearly no intercalary ribs,
and C) its subquadrate whorl section.
MeiL:Iurements. D Euw H w D/Euw% D/H0k
c. 514 15 6 6 7 40 40
c. 614 21 8 8 10 38 38
c. 514 30 12 12 15 40 40
c. 614 60 30 21 26 50 35
COI\IMENTS. This species is comparable
to "Douvilleiceras Martini d'Orb" as figured by
Sinzow (1906, p.171, pl.2, fig.13-17) but the
latter differs by the stronger development of the

36 F. ETA YO - SERN A
tuberculation at equivalent stages of juvenile
development, and because on the Colombian
species at adult sizes the ribbing is regularly fine
with exclusively primary ribbing whereas on the
Russian species primary and secondary ribs alternate
and the whorl section is depressed,
oblong and notsubquadrate as in the Colombian
species. No other comparable species is known
to me.
OCCURRENCE. Socota Member. Upper
Aptian.
This species is named in honor of the geologist
Andres Jimeno, former Director of the
Inventario Minero Nacional, and 1st. Director
of the Institute Nacional de Investigaciones
Geologico-Mineras.
Cheloniceras (Ep icheloniceras ) barreroi
n. sp.
Pl.2, Fig.l; Text-Figs. 4P, 4Q.
Holotype. C-514 (U.N.C.M.H.N.C.P.Ht.N.22).
This is a peculiar stubby Cheloniceras
species with the general appearance of a water
wheel. The umbilicus is deep an wide and its
sides vertical on each whorl. The earliest whorls
observed (adoral part of the second whorl) have
strong ventrolateral spines, and the umbilical
wall and flank form a continuous broad arc; on
the third whorl a subvertical rather high umbili·
cal wall rounds smoothly in to the convex
flank; on the adapical portion of the fourth
whorl the periventral tubercles appear faint on
flank as broad, slightly raised ribs, shortly after
every other rib develop mammiform tubercles
on the umbilical rim.
On the fifth whorl the adult ornamenta·
tion is well defined and characterized by heavy
primary radial ribs which have a spine at the
umbilical rim and a second heavy and stronger
spine at middle of the flank where the rib bifurcates
with the adoral branch thinner; on both
sides of the ventral median region all ribs develop
transverse crest-like tubercles and the mid·
venter is depressed.
At the beginning of the last preserved
whorl there is an intercalary rib, between two
branching primaries, which is as prominent as
the primary ribs, but on the central segment of
the whorl the bifurcating ribs follow each othl!r
without any intercalary rib and finally near the
aperture no bifUrt!iltions occur even though one
intercalary rib beginning at level of the midi ate·
ral tubercle may · be present, but the dominant
ribs are single prominent primary ribs.
The inte.tcostal spaces are twice as wide
as the ribs especially between two successive
primaries and narrower between the branches
of a bifurcating rib. At the end of the last preserved
whorl its section is very depressed, trans·
versely elongated and polygonal in outline, it
has a vertical u_bilical wall,flatdiverging adumbilical
half of Whorl, convergent adventral half
of whorl and flattened venter. The ribs stop at
the umbilical rim though when the test is preser·
ved a stressing of the growth lines occurs down
to the umbilical seam.
DIAGNOSIS. This species is characterized
by: A) a very depressed section of the whorl
and B) the development of its ornament which
begins with ribs laterally tuberculate and with
feeble swellings on both sides of the median
ventral line, they subsequently develop mammiform
umbilical tubercles and bifurcate from the
centrolateral tubercle, finally only tritubercula·
te single ribs are present.
Measurements D Euw H W D/Euw "fo 0/H%
C·S14 42 19 14 24 45 33
COMMENTS. This species resembles Cheloniceras
clansayesense (Jacob} (1905, p.4.3, pl.
13, figs. 4a, 4b,4c) but the Colombian species
develops its mature single ribbing earlier in the
ontogeny than the French species.
OCCURRENCE. Socota Member. Upper
Aptian.
Holotype. C-504 (U.N.C.M.H.N.C.P. Ht. N.23).
Four whorls are present on the largest
specimen; on the first whorl -apparently the
second of the phragmocone- widely spaced
pleats are present, they bear long spines along
the involution line, and disappear about the
umbilical rim; on the third visible whorl small
spine-like tubercles appear at the umbilical rim,
they connect to the ventrolateral ones through
a wide triangular like extension of the rib,
which itself extends on the umbilical wall to
· the umbilical seam; at the same time one or two
intercalary ribs develop as fine pleats between
the primary ribs, it disappears about the umbi·
Iical rim and has ven trolateral spines; at this sta·
ge the umbilical wall is vertical.
On the last preserved whorl there is an
alternation of one or two narrow and acute
intercalary ribs, which may have a tubercle or
lack it at the middle of the flank, but they
develop tenuous bullae-like tublercles on both
sides of their median ventral depression. Spora·
dically one of the primary ribs bifurcates at the
lateral tubercle with either the adoral or the
adapical- branch of it being the most prominent.
One intercalary rib may rise from the periumbi·
Heal tubercle of a primary rib. In general all ribs
describe a wide adoral concavity from the
umbilical seam to the lateral tubercle, from that
point Jhey slant slightly forward producing a
slight bow at the level of the lateral tubercle, .,
this is especially notable on the intercalary ribs.
lmfnediately adventral to the lateral tubercles
the ribs are sligh tly depressed and then they
fonn an elevated periventral tubercle; the
depressed ventral medhm region between the
periventral tubercles forms a wide shallow
groove.

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 37
The section of the whorl between the ribs
is suboval, almost as high as wide, but at ribs it
is polygonal with the umbilical wall subvertical
and high.
DIAGNOSIS. This species is characterized
by A) its high whorl section and B) the oma·
ment of its adult whorl -which varies from two
to more intercalary ribs between primaries or
coupl«!S of primaries.
Meuurement.l D Euw H W DJEuw% D/H%
C·604 4'1 26 22 7 44 38
. COMMENTS • .COmpared. to Chelanicerll$
(Epicheloniceros) barreroi n. sp. the angle for·
med by the segments of the ribs between lateral
aJ1d . adventral tubercles is obtuse in the latter
out in. Ch. (E.) pardai it is very steep, almost
ninety degrees; in the latter species the bifurca·
tion of the ribs is irregular contrary to the for·
mer species.
OCCURRENCE. Socota Member. Upper
J\ptlan.
This species is named in honor of geologist
Rafael Pardo.
Cheloni§ W te H fichelonicerizs.L
Jfonhar _q__ n. sp.
Pt 6, fig, 3; Text-fig. 4U.
1938 Cheloniceras clanseyense Jac., Riedel, p.
. 22, pl. 5, fig. 4,5, pl. 14, fig. 5.
1957 .Cheloniceras clanseyerue Jacob, Bilrgl, p.
.. 135. .
1965 Chetoniceros clanseyerue Jacob, Biirgl, in
·. Campbell and Btirgl.
Ilolotype. Specimen figured by Riedel, 1938,
Hypotype. l(UN.M.H.N.C.P. Hy. N.6)
.·· .. Only two specimens available (C-223].
The earliest part of the shell observed is distor·
d by .a malformation. On the adapical part of
e last preserved whorl the first rib that can be
observed res.embles a low rounded ridge which
attenuates and fades out near the umbilical rim;
it describes.a tenuous,.wide adoral concavity on
the whorlSlde and on the venter they project
formlilg a. wide adoral arc. These ribs have a co·
nical . tubercle in the middle of the flank and a
slight bump on both sides of the ventral median
lb:u. Th.e ribs are distant from each other and
are s.eparated by flat intercos spaces. Advan·
· u clng adorally the next rib has a slight periumbi·
cal mammiform tubercle which become
P.tominent on the next (3rd) rib. On subsequent
n,bs a.· . continuous strengthenir.g of the lateral
and yentrolateral tubercles is initiated but the
.rnbdical tubercles scarcely increase in size.
ar · groth lines describe a wide adoral
. ·ie w . c . begrns at the umbilical seam and
e:J;. nds to the periventral margin from which
.tnt they- project onto venter; in general their
·
trace follows that of the ribs. The whorl section
· at the preserved apertural end is transversely
subrectangular: the umbilical wall is oblique
and it rounds smoothly Into the convex sides
which themselves round smoothly into a
flattened or broadly arched venter. The umbili·
cal wall seems to become oblique in the adoral
portion of the last whorl. There are 13 ribs on
the last whorl preserved.
DIAGNOSIS. This species is characterized
by: A) its tapering ridge-like ribs slightly exten·
ding onto venter, B) the uneven development of
the size and shapes of the tubercles: mamml·
form, conical spinose and ·nod6Se: for adumbill·
cal, centrolateral and periventral respectively'
and C) its wide flattened intercostal spaces with
only fine growth striae.
Meuurementa D Euw H W D/E1.1,w% DfH%
C·223 33 14 12 16 43 36
COMMENTS. This species was referred
by Riedel to Jacob's species (1905, p.413, pl.13,
figs. 4a, 4b, 4c; 1906, pl.l, fig. 7a.7b) but on
the latter the ribs bifurcate from the lateral
tubercle, the opposite is true for the Colombian
species.
OCCURRENCE. Socota Member. Upper
Aptian.
This species is named in honor of Dr.
Leonhardt Riedel.
.f!Jelonic!Jr! C¥EJchelonf!:eras} huertasf.. n.
sp.
Pl.2, fig. 4; Text-figs. 4Y, 4$ .
Holotype. VL-7-Sa-11. (U.N.C.M,H.N.C.P.Ht.
N.4).
Paratype. (U.N.CM.H.N.P. Pt. 24,25).
A) Up to 10 mm D. The second whorl of
the phragmocone is coronate, it has a row of
spiniform tubercles along the periventral margins
(=involution line); from this row of tubercles
the flanks descend into the subvertical umbilical
wall. On the third whorl, ridge like folds extend
from the umbilical seam, describing a tenuous
adoral concavity, up to the periventral tubercles
with the maximum depth of the concavity at
the umbilical rim; however on the adventral
half of the whorl they are slightly convex
ad orally or nearly straight. One or two of such
folds however bend on the adumbilical half of
the flank in such a fashion that they appear to
arise from the umbilical rim of the preceding
fold. From the periventral tubercle the ribs
cross the venter; the intercostal spaces are more
than twice as wide as the ribs; they are natte·
ned and they are at times interrupted by
a constriction-like groove. The whorl section
has a sub trapezoidal outline, with a broad roun·
ded venter.
B) Up to 25 mm D (same specimen). The
ribs are stronger, they describe a continuous
shallow adoral concavity from the umbilical
seam to the periventral margins from where

38 F. ETAYO - SERNA
they project slightly forward on venter, for·
ming a wide adoral arc. At this point the ribs
are differentiated between : A) primary ribs
which develop a tiny bullae like periumbilical
tubercle, that are acute to subrounded on the
flank up to the lateral tubercle, and then they
become rounded, B) intercalary ribs attenuated
in relation to the primary ones; they extend to
the umbilical seam as fine threads but become
well stressed on venter and C) secondary ribs
connecting the lateral tubercles and developed
adapically to the primary ribs. There is no regu·
larity in the occurrence of one type or the
other but at least on this specimen, after two
successive bifurcations there may be several, up
to three, single intercalary ribs.
The primary ribs are more prominent on
the venter and faintly flattened along the
siphonal line . Those ribs which bifurcate are
followed adorally by a constriction-like sulcus.
The intercostal spaces are slightly wider than
the ribs. On the last third of the last whorl of
this specimen all ribs tend to have the same
strength on venter, at the same time the intereostal
distance increases. There are 45 ribs on
venter of the last whorl on the specimen studied.
C) Up to 40 mm D. Although in the pre·
viously described stages of growth the ribs are
less strengthened than in the specimen selected
as the holotype, I am considering them conspe·
cific because the general development and the
shape of the ribs is the same. In one specimen
there is a widening of the ribs toward the aper·
ture but this, as judged by sporadically developed
similar spaces at intermediate sizes, is inter·
preted as due to hampering of rib development
during growth.
The last whorl of the largest specimen
examined has about 45 ribs on the venter, they
are sin,gle rounded, closely spaced, separated by
constrictit;li1Jike intercostal spaces; they bear a
: Hny periUmbilical spine, and an spinose centro·
jate)l.ibercle. from which ribs may bifurqate,
and; sci.n\e'primary ribs at the adapical 'portion of
'"'the whorl have a'tenuous ventrolateral eleva.lon.
The, nb i;?ild to be equy strengthened though
th interealary ribs, atnuate more rapidly on
E! flanks.
' ; , · · · · ' ·
, . , DIAGNOSIS. '!'his species is characterizP-d
by! the development 'of its .. ornament which be·
gins with A) bifurcatihg primaey ribs and inter·
talary ribs, which B) grade into uniformly roun­
. ded, losely spaced ribs and i:lituberculate rib·
bing in the adult and C) the section of the whorl,
reniform throughout the ontogeny .
Measurements. D Euw
VL • 7 • Sa • 11 8 8
VL • 7 ·Sa · 11 23 10
VL
• 7 ·Sa· 11 41 51
H W D/Euw % 0/H%
8 3 37 37
9 18 43 39
16 23 36 39
COMMENTS. This species is similar toCh.
basseae Breistroffer (1936, p.156: Acanthoceras
(Cheloniceras) n. sp., Basse , 1928, p.138, text·
fig.15, plate 8, fig.1), but in the latter species
the section is almost circular, furthermore con·
trary to the new Colombian species the ribs are
uniform in size except "jusque' au voisinage de
l'ombilic a1 bord duquel elles semblent se grou·
per en donnant naisance a un tubercule", Basse
(ibid., p.138).
OCCURRENCE. Paja Fonnation (Arcillo·
litas abigarradas. Segrr.ent E). Upper Aptian.
This species in named in honor of the pa·
leobotanist Gustavo Huertas, of the Universidad
Nacional de Colombia.
cs-· - -ecmitesf._Y;!GiJ
Vec.mites Casey, 1962, part.4, p. 256.
TYPE SPECIES. Vecmites caprotinus Casey,
original designation.
flo.-, u?'>

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 39
from the centrolateral tubercle of a PrimarY rib
and the other appears in a subdue manner near
the umbilical rim; the primary ribs are wide and
flattened on the venter.
B) Up to 20 mm D [C-504]. With growth
one or two intercalary ribs tend to become well
individualized and at the same time the vertex
of the adoral ventral arc of the primary ribs tend
to be depressed suggesting ventral tubercles. •
C) Up to 45 mm D [C-504]. The flattening
or depression of the ribs on venter accentuates
with growth giving the ventral arc a truncated
aspect. The intercalary ribs become as promi·
nent as the primary ones except that they fade
out before reaching the umbilical rim. The
living chamber occupies about two thirds of the
last preserved whorl and It is characterized by
the irregular occurrence of the ribs, which are
well but variably extended onto the venter. The
Intercostal spaces are two or three times as wide
as the ribs. The section of the whorl is ttansver­
sely subrectangular and has rounded comers; the
umbilical wall is oblique. A dorsal shield is pre­
sent.
DIAGNOSIS. This species' is characterized
by: A) the broadly arched and truncated projec·
tion of the ribs on venter, B) the transversely
subrectangular whorl section of the adult, and
C) the discrete development of the ribs.
Me..uements. D
c. 04 16
C.• 04 20
0"04 46
Euw H W D{Euw0k D/H %
6 7 1 37 7
7 7 1 1 7
22 16 20 48 3
COMMENTS. This species differs from the
type species of Vectisites Casey (1962 = V.caprotinus
Casey, p. 256, pl. 40, fig. 9a, b, lOa, b,
te.xt · fig. 89a), as noted for the subgenus.
· . OCCURRENCE, Socota Member. Upper
Aptian.
· This species Is named in honor of Francisco
Zatnbrano, geologist of the Instituto Nacional
de Investigaciones Geologico-Mineras, Bogota.
Xe'W'ites 'Zambranoites J cruzi D..J
Pl. , fig. ; Text-Figs. 5A., 5B.
Holotype. C-50 4 (U.N.C.M.H.N.C.P. Ht. N. 26).
The first whorl observed seems to be the
first whorl of the phragmocoile and Is smooth;
the • . second whorl shows a high subvertical um­
bllic:al wall which changes abruptly into the
lllightly convex aide; very fine, widely separated
pleats. are visible on the test. On the t."l ird visible
who.:d those pleats become wide and low and
they have a faint conical node at the line of in­
volution which at that point is about at the
bounduy between the middle and adumbilical
thirds of the flank. At the adapical portion of
the lt whorl o.f this specimen (4th of the phrag­
mocone) the nbs are clearly visible from the
wnbllical seam; up to the lateral tubercle the
nbs describe a tenuous adoral concavity. then
they slightly bend at about the central third of
fiank and rm aUy they describe a wide adoralconcavity
up to the periventral margin and project
onto venter, describing an acute, almost
chevron-like arc; this bend accentuates with
growth of the whorl.
The ribs become progressively depressed
along the ventral median region in such a
manner that at the adoralmost portion of the
conch there are two elevated tubercle-like
shoulders on each side of the venter. The first
third of the length of the last preserved whorl
has a faint non-tuberc:ulate intercalary rib
which begins at the periumbilical margin. The
living chamber occupies about two thirds of the
last whorl and is characterized by loss of the intercalary
rib and increasing distance between
the primary ribs. The intercostal spaces are wi·
de, one and a half as wide as the ribs if one
intercalary rib is present but from three to four
times when the intercalary rib is missing, this
is especially noticeable on the internal mold.
The umbilicus is graded shaped, deep. The intercostal
whorl section at the adaperturalmost
part of this specimen is rounded subquadrangular.
DIAGNOSIS. This species is charaterized
by : A) its. small, relatively compressed conch,
and B) the rapid development and accentuation
of the adoral arching projection and depression
of the ribs along the midventer.
Meuurements D Euw H W D(Euw % D(H0k
C·604 2 10 10 12 40 40
COMMENTS. This species diffe rs from
Vectisites (Zambranoites) zambranoi n. sp. be·
cause of its rapid acquisition of a strong ventral
projection of the ribs.
OCCURRENCE, Socota Member. Upper
Aptian.
This species is named in honor of Jaime
Cruz, former Subdirector of the Instituto Na·
::ional de Investigaciones Geologico·Mineras,
Bogota.
Vectisites oza mbranoite!)._ mateusi n. s
Pl.6, fig. 2 ':" - ' '
Holotype. VL-11-3 (U. N. C. M. H. N. C. P. Ht.
N.27).
Paratype. (U. N. C. M. H. N. C. P. Pt. N.28).
Two specimens are available. The conch
has moderately compressed sides and slightly
rounded venter. The adapical portion of the pe·
nultimate whorl bem close pleats on the flank,
ltl umbilical wall is vertical; toward the adapical
region of the last whorl the primary ribs begin
to diffe,rtllltiat.e, they are flexuous, adorally con­
cave on the external part of the umbilical wall,
adorally arched on the central third of the flank
and finally projected onto the venter. The part
of the ribs on the adumbilical third of flank are
flanged but a tubercle is not developed. On the
ventral median line of the adoral portion of the

40
last whorl the ribs are inconspicuously flattened.
On the last preserved whorl the ribbing is prominent
and consists mostly of primary ribs, so
me of them in couples; intercalary ribs are also
present, they are initiated in a subdued manner
near the adumbilical third of the flank.
DIAGNOSIS. This species is characterized
by: A) the ontogenetically late and inconspicuous
(if any) development of the tuberculation,
B) its strong flexuous ribbing, and C) its
compressed suboval whorl section.
Meumementl D Eu.w H W bfEu.w0k D/H%
VL-11-3 33 12 13 7 36 39
VL-11·3 30 11 13 13 37 43
COMMENTS. Compared to the other species
In the genus Vectisites described from Colombia,
this is the only species which combines
a strong flexuoslty of the ribbing with great
attenuation of the tuberculation (?).
OCCURRENCE.Paja Formation (Arcillolitas
abigarradas. Segment E.). Upper Aptian.
This species is named in honor of Luis E.
Mateus, geologist of Ministerio de Minas, Bogota.
V£ r;,tes _ CZambranoites cg4£_nqj_ n. sp.
Pl.6, 1g. 4, Text-figs. 5L, P.
Holotype. C-514 (U.N.C.M.H.N.C.P.Ht. N.28)
Only one specimen is available, it has the
shell preserved. The conch is stubby and compressed.
The ornament consists of ribs which
usually develop in pairs at the periumbilical
·margin; of these ribs, the adapical one is thic·
ker and rounded, radial, flanging outward on
the adumbilical half of the whorl side, it is be·
veled on the periventral zone and transversely
elevated in a bullae-like fashion on both sides
of a depressed and narrow median ventral region;
futher adorally the ribs tend to be slightly
projected on venter; the adoral or secondary rib
tapers toward the·.'Un1bilical margin, on venter
it is narrower andlower than the primary one
and does not develop periventral tubercles on
the depressed median ventral zone. Sporadically
an isolated primary rib develops.
The intercostal spaces between a prima·
ry and· its paired secondary rib is as wide as the
primary rib, but the intercostal space between
that secondary and the following primary is
wider than the primary rib itself. The ribs in
general are high and rounded and the intercostal
spaces are channel-like. Near the aperture
the ventrolateral bullae disappear. The intercostal
section of the whorl is low subquadrate with
rounded comers and convex sides. The 1J.mbilical
wall is oblique. There are 25 ribs on venter
of the last whorl. The apertural border is plain,
with a slight reflection at the umbilical wall.
DIAGNOSIS. This species is characterized
by: A) its depressed octagonal costal whorl section,
B) its heavy, rounded ribs, C) the presence
F. ETA YO · SERNA
of ventral bullate swellings only on the ribs, and
D) the angular periumbilical and centrolateral
bending of the ribs without development of tubercles.
Meumementl D Euw H W DfEuw· % D/H %
C·614 36 16 12 12 44 33
COMMENTS. This species shows some re·
semblance to the type species Vectisites caprotinus
Casey, (1962. p. 526, pl. 40, fig. 9a, 9b es·
pecially), but on the English species the lateral
tubercles persist longer; on the other side the
Colombian species is more depressed than
Casey's species.
OCCURRENCE. Socoti Member. Upper
Aptian.
This species is named in honor of Raul
Cadena, Universidad Nacional de Colombia,
Bogota.
D£tisits.l,Zg_mfJronQj{esLfl.ug_tteJi n. sp.
Pl. 6, lfg.2; Text-fig. 5!.
Holotype. C-514 (U.N.C.M.H.N.C.P.Ht. N.29)
Paratype. C-514 (U.N.C.M.H.N.C.P.Pt.N.29)
A) (C-514). The earliest whorl observed
(adoral part of the second whorl) has a depressed
subelliptical section: a broad arc connects
the center of the flanks, then the whorl rounds
smoothly into the umbilical wall which is incli·
ned. The sculpture at this stage consists of in·
conspicuous folds which describe an adoral
bend on the middle of the flank, and is delimi·
ted by a concavity both adumbilically and adventrally,
these pleats are projected onto the
venter forming a wide adoral arc.
On the adoral portion of third whorl the
ornament is already visible: it consists of
prominent riblets which begin at the imprecise
umbilical rim; from the point to the periphery
the ribs describe one adoral arc at the center of
which a conical tubercle springs; from this
tubercle the ribs describe an adoral concavity
and then extend onto venter describing a
linguiform arc. The intercostal spaces are at
least three times as wide as the ribs, much
greater on venter; they are covered by growth
lines which parallel the ribs.
B) At 15 mm D [C-514 ]. At this diame·
ter the w_horl section increases in height and the
conical nodes occupy a more central position
on the flank; the adventral half of the flank is
compressed, at the same time on the internal
mold the ventral linguiform projection of the
ribs flattens in a visor-like fashion and contemporaneously
on both sides of the ventral me·
dian line the ribs begin to raise in transverse,
faint but perceptible tubercles. On the adumbi·
lical.half of the flank the ribs flare in a charac·
·
teristic fashion.
C) Up to 30 mm··n ( C-514). On the lar·
gest specimen the lateral nodes begin to fade
out contemporaneously with the development

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 41
of the ventral nodes. The final type of ornamen­
tation -as far as it is known- consists of well
marked slightly flexuous, well separated ribs
which project a bit onto venter where they are
slightly depressed along the ventral median area
and slightly raised on both sides of that area.
The ribs begin at the external part of the umbi­
lical wall with a little thi!:kening but are not tu·
berculate; there Is usually one intercalary rib
whicll begins at the periumbilical rim whre it
is inclined toward the preceding rib. The inter·
costal whorl section is transversely rectangular
with rounded comers. The umbilicus is deep,
slightly inclined.
DIAGNOSIS. This species is characterized
l:ly: A) the early and brief strenthe ing of its
lateral tubercles and the ventral hngu1form pro·
jection or the ribs, and B) its compressed sub­
qudrate whorl section.
Measurements.
c. 514
C·514
D Euw
16
6
30 12
H W D/Euw %
7 8 33
12 14 40
D/H%
46
47
COMMENTS. This species differs from
Vei:tisites (Zambranoites) zambranoi n. sp. be­
cause on the latter the projection of the ribs on
venter is retained or stressed to a greater diame­
ter. Ve ctisites (Zambranoites) cruzi n. sp. by
cofrtrast stresses its ornament very early in the
otitogeny and the intercostal distance is very
.lile,
OCCURRENCE. Socota Member. Upper
Aptian.
This species is named in honor of Hermann
Duque, paleontologist of the Instituto Nacional
? } nvestigaciones Geologico-Mineras, Bogota.
f : LC( yp a : a .:,o!.}!_ te (8:2
HJ!pacanthoplites Spath, 1923, p. 64.
2!1
TYPE SPECIES. Acanthoceras mille tianum
(d'Orbigny) var. plesiotypica
Fritter, original designation.
raacanthoplites (?)
os_naliciae n. SJ?.: ..
PI03, fig. 11.
Ho)otype. T.P.I. Guaduas (U.N.C.M.H.N.C.P.Ht.
, . · N.30).
Paratypes. T.P.I. Guaduas (U.N.C.M.H.N.C.P.Pt.
N30,31).
·. A) Up to 15mm diameter{T.P.I. Guaduas].
At 'the .innermost whorls (D:9mm) the section
ubquadrate with rounded periventral mar·
ipDS and venter; the sides are convex, the umbi·
heal willl is subvertical. The ornament consists
o ribs which begin at the umbilical rim and are
S!lghtly flexuous, rounded, with short vertical
s.les but flattened top and they progressively
Wl.d.en . from the umbilical margin toward the
Penphery; the ribs are separated by subequal
!n.tercostal spaces; the former cross the venter
1" a feeble adoral curvature. The ribs are
slightly depressed along the ventral median line
producing on each side feeble transverse bullaelike
elevations: Occasionally a minute conical
tubercle developes on one rib (??). The ribs may
also bifurcate on the adumbilical third of the
flank; they tend to become more rounded with
growth.
B) Up to 30 mm D [T.P.I. Guaduas]. The
early portion of the last whorl is subquadrate, it
has flattened sides but rounded periventral and
ventral margins; the umbilical wall is subvertical
and rounds smoothly into the flanks; at the
adoral portion of this specimen the whorl sec·
tion is subrectangular. The ornament consists of
ribs which initiate midway on the umbilical
wall. The ribs are rounded,. well separated ,
sigmoidal; irregularity some of the ribs bifurcate
on the adumbilical third of the flank, both
from the adapical side of the primary ribs or
from the adoral side of them ; there are intercalary
ribs also. The ribs become slightly higher
and wider on the venter. The ribs flare out on
the umbilical rim and are slightly weakened on
the middle of the venter.
C) Up to 50 mm D [T.P.I. Guaduas]. The
ornament is characterized by a conspicuous alternation
of ribs which on one side appear as
primary but on the other as secondary. Toward
the aperture the venter is well rounded, the ribs
tend to be prorsiradiate uniform and elevated
on venter. The ribs have a weakly biconcave profile
and are slightly elevated on the venter. There
are 37 ribs on venter of the last preserved whorl.
DIAGNOSIS. This species is characterized
at mediun and large sizes by : A) its radial to fee·
bly flexuous ribbing, B) the tendency of the
secondary ribs to branch from the raised peri·
umbilical flanges of the primary ribs and C) the
tenuous periventral bullate swl#llings on venter.
Measurements. D Euw H W D/Euw "/o D{H%
T.P.I. Guaduu 15 5 7 7 33 46
T.P.I. Guaduaa 30 10 13 12 33 43
T.P.I. Guaduas 32 18 21 18 35 40
COMMENTS. A comparable species was
described by Liss6n (1925, p. 27, pl. 2, figs. 4, 5)
as "Parahoplites Mill e tianum d' Ob. sp.", but
very little can be determined from his illustration
or description except that the Colombian
and the Peruvian specimens look very similar.
The neotype of Hypacanthoplites plesio·
typicus (Frittel) as figured by Casey {1965, p.
42tl, Text-Fig. 155b, c) has stronger and
flexuous ribbing on the flanks than on the
Cclombian species. Furthermore on the former
the ribs are thick on venter [on the illustration]
but they are thin in the Colombian species.
OCCURRENCE. Socota Member. Upper
Aptian.
This species is named in honor of Miss.
Alicia Vanegas Leyva, former librerian of the
Servicio Geologico Nacional of Colombia.

42
Hypacanthoplites dognaliciae n. sp. ?
Reference. Specimen C· 222.
The early portion of the last whorl is hi·
gher than wide with maximum inflation on the
adumbilical third of the flank; the sides are fla·
ttened and slightly convergent towards the wide
flattened venter. The umbilical wall is oblique
and rounds smoothly into the flanks. The early
part of the last whorl has fine acute ribs, which
begin on the middle of the umbilical wall or at
the umbilical rim; these ribs are more or less
falcifonn on flanks.
The primary ribs are characteristically
prominent, flaring out on the adumbilical third
of the flank whereas the secondary ribs may
flank from the adoral side of the primary ribs
on the adumbilical third of flank, or they may
appear independently but they are not empha·
sized adumbilically. The intercostal spaces are
twice as wide as the ribs. On the adventral third
of the whorl and on venter the ribs 1\le flattened.
The ribs are almost imperceptibly elevated on
venter. There are 38 ribs on the .renter of this
specimen.
Measurements D Euw H W D/Euw%DfH0/o
C·228·B 32 11 14 12 34 44
COMMENTS. This specimen differs from
the holotype mostly because the mature ('?) living
chamber appears at a much smaller diameter,
this. occupies two thirds of the last preser·
ved horl.
OCCURRENCE. Socota Member. Upper
Aptian.
r """ .
-G";----ad:rham}cer-¥·'g·ni.
'm:E"SPECiEs. Jua;;;r; ;;
;··}u-;,;;trhan
;
mi n. g.1 n. sp. L>
:: Yu,r£nay•O. Kl."ttr v-- 16.>o•f; .-1!/Ar
.
DIAGNOSIS. Evolute conchs reachmg
moderate size. The early depressed whorl section
rapidly changes into a compressed oval sec·
tion. The early ornament consists of fine
flexuous, closely spaced ribs which cross the
venter uninterruptedly, these ribs progressively
separate from each other and widen on venter,
likewise the ribs differentiate between primary
and intercalary; with growth the primary ribs
flare out on the adumbilical half of the flank,
all ribs are less prominent on the adventral half
of the flank. AU' ribs have a tendency to be
excavated on their adoral face along the ventral
median line, producing on both sides of it more
or less conspicuous elevations. On the living
chamber the depression of the ribs abruptly
ceases and they have a girdle like appearance on
venter f= Colo mbiceras-like stage] . No tubercles
occur throughouWh.e ·ontogeny.
.
COMMENTS. This genus has already been
illustrated as "Du{renoyia" by Casey {1965,
p. 418, text-fig. 152): "Dufrenoyia sp. example
showing Colombiceras·like sculpture on final
quarter-whorl, indicative of a link between the
F. ETAYO - SERNA
Deshayesitidae and the Acanthohoplitinae,
"Upper Aptian, near Bogota, Colombia (Univ.
California no. C-1325)". I have examined this
specimen and as is shown on the right-hand fi.
gure in Casey's illustration the depression of the
ribs along th ventral median line is accentuated
adorally before the "Co lombiceras-like" sculpture
suddenly develops. In other words, the depression
of the ribs ceases before the final living
chamber.
From study of this new genus, it ap·
pears that the "Clavate termination of the ribs
bordering the siphonal band" of the "post·nepionic
ventral growth" of Du(renoyiD (Caser,
1964, p.376) and the periventral "elevations '
of Juandurhamiceras are not homologous morphological
elements: on the latter the ribs in
early ontogeny cross. the venter uninterrupte·
dly and subsequently they tend to depress
along the ventral median line, but on the former
the reverse is true with the addition that
the ribs are interrupted on venter in an early
stage.
Previous to the present study precise in·
formation on the exact stratigraphic position of
Juandurhamiceras was not available. It is here
presented because together with specimens of
the type species I have found a specimen that I
consider conspecific with the specimen illustrated
by Casey (op. cit., text-fig.I52). I am making
it the holotype of a new species: Juandurhamiceras
joepecki n. sp., characterized by the
rapid acquisition of the "Colombiceras-like sty·
le of ribbing".
Comments on the specimen illustrated by
Casey, both as to its uncertain stratigraphic
position or its significance as a "link" have been
made by Wiedmann (1966, p. 45) and Wiedmann
and Dieni (1968, p.93), respectively. The
genus Juandurhamiceras differs from Colombi·
ceras (Spath, 1923), here understood to embrace
those species closely resembling the type
species, by the lack of any indication of lateral
tubercles, at any stage of owth. Incidentally
the tendency to proCiuce girdle like ribbings, i
believe, is not per se an indication of phlyoge·
netic linkage.
This genus is named in honor of Emeritus
Professor John (Spanish: Juan) Wyatt Durham,
of the Department of Paleontology, University
of California at Berkely.
...J.BtrodurhQ!!Ji"m uangurhamJ..n. sp ..
Pf.4, 1'ig.2; Pl.3, fig.5; Text-figs. 5C, 5J; 12.
Holotype. Santa Ana A.P.G. (U.N.C.M.H.N.C.P .
. Ht. 31).
Paratype. Santa Ana A.P.G. (U.N.C.M.H.N.C.P.
Pt. 32,33,34).
•
. ·-.,. . : •.
. . .
A) Up to 30 mm D (Santa Ana A.P.G.).
The early whorls were studied by disecting one
specimen. The protoconch is depressed; the
adapical section of the..second whorl is wider
than high , with its maximum width located at
center of flank, but the adoral portion of this
, ...

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 43
whorl is subcircular. The third whorl is higher
than wide.
The earliest ornament observed is on the
second volu lion and consists of annular fine
rounded ribs which are visible from near
the umbilical margin, they then trend pr;>rsira·
diate as a very elongated S on the convex·flank,
and cross the venter unihterruptedly; they are
as wide as the intercostal spaces though a cons·
trictlon-like intercostal space can be observe
on this specimen. The ribs rapidly become narrower
than the intercostal spaces (adoral por­
tion of the third volution) and at the same tl­
l]le they broaden on venter; shortly after (H:7
mm) the ribs become prominent on the flanks;
contemporaneously the ribs begin to inflate on
the ad umbilical third of the flank and to con·
tractact on the adventral third; this contraction
is followed by the development of a slight de·
pression of the ribs on their adoral .side along
the median ventral line, this produces delicate
to accentuated humps on both sides of venter;
the ribs have not been observed to be interrup­
ted on venter. At this stage of growth the ribs
are .
prominent, separated by wider intercostal
apaces and they are straight of feebly flexuous.
. • B) Up to 41 mm D (Santa Ana A.P.G.).
As in the preceding specimen, the successive
whorls only cover the external third of the preceding
whorl; the umbilical wall is inclined and
evenly rounds into the flanks; the periventral
rnaigiq is abruptly rounded and the venter is
rounded to flattened.
The . ornament consists of primary ribs
which appear about the middle of the umbilical
wall but may extend, on exterior of shell to the
umbilical seam. The ribs describe a slightly adoral
concavity in the umbilical region, then a con­
laxity on the adumbilical and middle thirds of
th flank where they are flared, then they are
febly concave adomlly or straight on the
adventral third . of . the flank, there they are
.flattened and contracted; the ribs cross the
l't!.n ter straight, flat-topped and prominet; along
. tbe periventral margin the ribs have delicate
lvations. The ribs are now differentiated into
cp,unary and secondary ribs, the former genera­
JI:y· flare on ftanks out to the involution line
m :\Vhere .they are less prominent; the secon·
g!!Y ribs anse imprecisely outside the umbilical
j(,',; ::Sn:;;nrlnt
f»1 111Jd generally do not flare out.
t
:!a
f:lt:1Ve PMl&Q' or secondary. ribs occasiona·
.t'Wl;lll· The intercostal spaces are almost
, c . • -, I1S wide as the ribs. The periventral
,Iy.a,fions on the ribs attenuate towa..tl the
14.o. end of the conch at this diameter. The
;g ell8Jllber ccuJ?ies three four!bs (3/4) of
.
iila·'lution, on Its venter the ns broaden
'"· "'frund .
and th adventral elevations disap­
, . owever, particularly on the in tern a! mold.
!l_dQ face of the ribs on venter show a
ctetllctlon.
.. _,:,;:·
.. ;
G
DIA NOSIS. This species is characterized
by: A) its moderately large size and evolution,
B) the regular alternation of feebly flexuous,
wen spaced, primary and secondary ribs on
middle and late stages of growth, and C) the
;JrJ: ri:. ssing of ventral "ele·
- - .-:"i"':.-""·
Meuurcneru D Euw H w 0/EUW 0/H No.R
% %
Sta. Ana ·1 30
Sta. Ana · 2
Sta . .Alla ·3
Sta. Ana •4 26 10 11 8 38 43 20
Sta. Ana · r. 26 11 10? 8 44 40'1 21
Sta. Ana • 6 30 14 12 9 47 40 2&
Sta. Ana · 7 36 167 1& 10 .42? 42 26
Sta. Ana · 8 29 12 12 9 41 41 22
Sta. Ana • 9 37 17 13 1 46 36 24
Sta. Ana ·10 437 19 17 12 44 39 20
Sta. Ana ·11 39 19 16 10 49- . 41 26?
Sta. Ana ·12 38 20 15 11 63 39 21
Sta. Ana ·13 367 17 1& 10 47? 42 . 24
Sta. Ana ·1 4 48 24 18 12 50 38 .• 2&
Sta. Ana ·1 5 36 16 13 10 46 37 24
Sta. Ana ·16 60 26 18 13 62 36 . 215
Sta. Ana ·17 417 19 16 12 46 36 26
Sta. Ana ·19 337 14 13 9 42 39 22?
Sta. Ana ·20 267 117 11 ? ? 7 . 26?
Sta. Ana •26 41 21 15 10 51 36 22
Sta. Ana ·27 36 16 13 9 43 · 37 21
Sta. Ana ·30 59 30 21 16 61. 35 28
Sta. Ana ·31 64 28 21 15 62 39 24
Sta. Ana ·34 407 18 16 10 45 40 26
Sta. Ana ·35 31 14 12 9 46 39 22?
Sta. Ana ·36 37 17 14 11 46 38 26
Sta. Ana ·37 36? 18 13 10 46 37 23
Sta. Ana ·38 37 18? 14? 10 49 38 21?
St.. Ana ·39 327 16 13 9 47 40 19
Sta. Ana -40 35 17 13 9 48 37 207
Sta. Ana ·42 49 24 21 11? 49 43 28
COMMENTS. Same as for the genus.
OCCURRENCE. Socota Member. Upper
'
Aptian.
J!MmdYdJamit{lJIS joepecki.,n. sp •
lil: 4, fig. 5.
Holotype. U.C.M.P •• C -1325 (Dlustrated by Casey,
1965, p. 418, text-fig. 152).
Hypotype.Sta. Ana 9 (U.N.C.M.H.N.C.P.lly.7)
Only one specimen is available (Sta Ana
A.P.G. 19). Very flat, slab·like sides, planar ven·
ter and very wide, radial ribs which are like clove
buds; ther are slightly but clearly flanged on
the adumbihcal third of the Dank. On t.'t e In·
temal mold the intercostal spaces are one and a
half times as wide as the ribs; the ribs are very
wide on venter and cross it l in early.
luqndurhamicras_gj[_qldgj,
n. sp.
PI. 3, fig:-"!3.
Holotype. Sta Ana A.P.G. N. 42. (U.N.C.M.N.
C.P.Ht. 32) •

44 F. ETA YO · SERNA
One large specimen is referred to this species.
The early internal whorls are covered with
fine rounded ribs, convex on the adumbllical
third of the whorl ; some of them, especially
those which begin at the umbilical wall are prominent
and flaring (=primary ribs); the secondary
ribs start at the periumbilical margin usua·
lly in pails, they are thin. On the last preserved
whorl the ribs are fine, particularly on the in·
temal mold. The primary ribs describe an adoral
concavity on the umbilical wall and part of the
periumbilical third of the flank, then they des·
cribe an adoral bow, sporadically very strong,
approximately on the central third of the flank,
on the remaining third they develop another
adoral shallow concavity and the profile of the
ribs is consequently biconcave; the ribs are slightly
thicker but rounded on venter where they
are feebly elevated. The whorl section is higher
than wide, It has an inclined umbilical region
which rounds into the flank; the periventral
margins are rounded. The last whorl has 28 ribs
on venter; the living chamber is preserved as half
the length of the last whorl.
DIAGNOSIS. This species is characterized
by: A) the delicately humped periventral margin
of the ribs is transient, B) the flexuous rib·
bing starts early in the ontogeny, and C) the rib·
bing is less prominent.
Me&llll'emenu.
D Euw H W D/EUW D/H No.R.
Sta. Ana 42 49 24 21 11? 49 43 28
. COMMENTS. This species differs from
Juizndurhamiceras juandurhami n. sp., because
on the latter the whorl section is more contrac­
.ted adventrally, and its ribs have conspicuous
periventral elevations throughout ontogeny.
OCCURRENCE. Socota Member. Upper
Aptian.
This species is named in honor of Mr. Car·
los Giraldo of the Instituto Nacional de Investi·
gaciones Geologico-Mineras, Bogota.
cG·"":If -!fPfii
Acantho hoplites Sinzow, 1907, p.458.
. 19;·\
TYPE SPECIES. Acanthohoplites aschiltaensis
(Anthula), subsequent desig·
nation, Spath, 1921.
Acanthol!gp_lites boureti[grme. n. sp.
Pl .5, fig. 2; Text-fig. 5U, 5V.
Holotype. C-127 (U.N.C.M.H.N.C.P.Ht. N.33)
Paratype. VL10·10 (U.N.C.M.H.N.C.P.Pt. N.35)
"?1938 Acanthoplites bigoureti Seusnes, Riedel,
p.45, p, J , _ . , g.7, pl.14, fig. 24.
19S8 Acrrfohbplites bigoureti sensu Riedel
(non Seus.), Etayo-Sema, p.20, fig.3.
1968 Acanthohoplites bigouretii sensu Riedel
(non Seusnes), Etayo-Sema, p. 28, tab.L
i970 Acanthoh-(oplites) bigoureti, Wiedmann,
p.484, ex review of Etayo-Semas's paper.
Only half an individual is available. On
the earliest observed whorl there appears to be
bullae-like tubercles along the line of involution,
however the preservation does not permit one
to be sure of this, after these bullae there is a
tract on which pleats rather than ribs are developed.
At this stage of growth the whorl section
is depressed; the umbilical wall is subvertical
but there is no well defined umbilical rim. At a
larger stage (on the penultimate whorl) the ribs
differentiate. The prominent primary ribs begin
at the umbilical seam, they trend across the
umbilical wall and adumbilical half of the flank
describing a slight adoral concavity; one or two
intercalary ribs develop between the primary
ribs, they attenuate before reaching the umbili·
cal seam.
On the last whorl the intercalary ribs are
present in groups of two or three, of these ribs
the adoral one sometimes inclines towards the
immediate adoral primary rib as lf branching
from it. The primary rib develops a prominent
triangular area with a spine; from this tubercle
the ribs bifurcate or trifurcate. The in tercostal
spaces are slightly wider than the ribs when
shell is preserved but they are one and a half
times as wide as the ribs on the internal mold.
The ribs themselves have steep sides and roun·
ded top, they describe a wide concavity on the
flank and project on venter where they are
slightly wider and flat-topped, the latter .is.
particularly conspicuous on the intemlll mold,>
On the venter the ribs tend to be :equally
developed but occasionally some are narrower.
At the beginning of the last whorl the section is
subcircular, at its adoral part it becomes ogival,
slightly compressed ad orally.
DIAGNOSIS. This species is characterized
by: A) the accelerated strengthening of its oma·
ment, especially the lateral tubercles, B) the
constancy of the wide intercostal distance, C)
the dominant flaring character of the ribs, and
D) the ogival section of the whorl on ribs.
MeaUrements D Euw H W D/Euw D{H No. R.
•;, Ofo
C-127 24 11 9 9 46 37 21(1/2)
COMMENTS. The section of the young
specimen described by Jacob as "Douuilleiceras
bigoureti Seunes sp." (1905, p. 415, pl.3, fig.
Sa, 6b) is transversely elongated, lenticular. The
inner whorls of the Colombian specimen appears
to have more ribs than the specimens refe·
rred to Seunes' species and figured by Pervin·
quiere (1907, p.195, pl.S, fig. 37, 38) both sha·
re however a circular section (intercostal) of the
whorl.
c;'5eunes (1887' p.567) previously 'noticed>
that in this group of taxa the young specimens ·
of related (?) species are similar, the species
being differentiated .. only in the adult stages.
Seunes' figured specimens are larger than my
specimen, however, their primary ribs are out·

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMCNITES 45
standing club-shaped contrary to my species on
which the intercostal spaces are wide and the
nbs only slightly increase their width.
OCCURRENCE. Shales above the Socota
Member and below the Capotes Member. Upper
Aptian. Paja Formatiol). (Arcillolitas abigarra­
das. Segment E). Upper Aptian.
cnwohonlites seunesitjmn.t n.sp.
. .7 , 1g.8; Text-fig. 5Q, 5R.
llolotype. C-127 (U.N.C.M.H.N.C.P. Ht. N.34)
Paratype. C-127 (U.N.C.M.H.N.C.P.Pt. N.36)
A) Up to 24 mm D. This specime!l has
the iimer whorls leached away ; the penultunate
whorl has periodically raised and elevated pri­
mary ribs w..hich bifurcate at the umbilical rim;
between two of the primary ribs there are two
or three secondaries, the fanner appear at the
umbilical seam but the latter usually do not.
The umbilical wall is subvertical and rounds rather
abruptly into the flank. On the third
or last preserved whorl, the primary ribs begin
to . develop triangular tubercles which have a
· small spine on top, from them the ribs bifurcate.
All the ribs cross the venter with similar strength,
they are almost rectiradiate and they cross the
venter nonnal to the median ventral line. When
the. shell is preserved the ribs are as wide as the
intercostal spaces, they have steep sides and
rounded tops. The intercostal whorl section has
flattened sides and broadly rounded venter,
it is higher than wide. Toward the aperture one
intercalary rib usually occurs between two
primary ribs lacking tubercles or with only
a minute conical one but without a bifurcation.
· .• B) Up to 48 mm D. In this specimen, the
:ho]otype, from the third whorl on, the oma­
Q:tent consists .of one intercalary rib , tapering
· toward the umbilical rim, between prominent
pri:rriary ribs with subre.ctangular profile; all
>P.s cross the venter straight and became slightly
.?IViened. The ribs are slightly narrower than the
ifitercostaLspaces where the shell is preserved
,ut on the internal mold the spaces are at least
'twice as wide as the ribs; the umbilical wall is
sh:ort and rounded.
'-' : DIAGNOSIS.· This species Is ch8lacteri­
ze_ by: _A) .a transito _ ry tuberculate stage (up
,/ttl: the th.irdwhorl), With numerous cloS£:ly spa­
},- rib and B) the adult stage on which stron­
;flf: J:[a,nn_g rect!radiate primary ribs and less pro­
;iiJ#.ent Intercalary .ribs alternate; all ribs are
::·\Y c:ontracted on the adventral third of the
;;_-menta D Euw H W D{Euw D!H No.R.
;_ ··< ).· ;c:.iz7 . 24 10 8 9 r; ;; +4o
x.;i. -';.'C-127 48 24 17 16 &o 31'i 20(3/4)
A
:: .COMM?NTS. This species ;esembles
aw{Johplrtes _senesi (Jacob) (Br"istroffer
"
Pi 7 · Douu1llezceras bigoureti var seunesi
95• Ptr - 416, pl. 13, figs. 7a, 7b), but
atter ass onger ornamentation, the whorl
section is more compressed, and the intecalary
ribs are shorter than on the Colombian species.
OCCURRENCE. Unnamed beds above the
Socota Member and below the Capotes Member.
Upper Aptian.
A£an.thh O-¥ J.i1 lLtasu,nQ.,n. sp.
Pl. 7, fig. 2, Text- 1g. 5Z, -
Holotype. C-157 (U.N.C.M.H.N.C.P.Ht. N.35)
Only one specjmen is available. The inner·
most observed whorls have the umbilical wall
convex, it merges into the flank without defi·
ning a rim; the :flanks and the ·venter are evenly
convex but the whorl section is wider than high.
At this stage the ornament consists of rounded
ribs, almost as wide as the intercostal spaees,
they are annular to slightly prorsiradiate, they
taper toward the middle of the umbilical wall.
Groups of three (common) to four of these
ribs are separated by slightly more prominent
ones which develop a large, conical to rectangular
tubercle immediately adumbilical to the
involution line ; from this tubercle the ribs bi·
furcate : the aaapical branch crosses the venter
straight but the adoral branch projects slightly
adoraly. Tn e intermediate rib nearest to the
emphasized primary rib is inclined as if arising
from the latter near the umbilical wall.
At a whorl height of 5 mm (correspon·
ding to the adapicalmost part of the preserved
whorl), the intercostal spaces are wider than
the ribs especially on the internal mold. At this
whorl height the venter is broadly 8lChed to
flattened, it has rounded periventral areas. On
the adventral half of the last whorl only one or
two ribs appear between two tuberculate ribs.
On the last quarter of the last whorl the primary
ribs do not bifurcate though the tubercle is
present; the intercostal spaces have become
very wide, channel like, but shallow, the ribs
have si,P.es sloping symmetrically (approxima·
tely 45 ?) and have a subrounded top. The aperture
is rectangular with rounded comers and it
is wider than high. There are about 50 ribs on
the last incomplete whorl. Sometimes there is a
:onstriction-like interspace, adoral to the ribs
with a node.
DIAGNOSIS. This species is characterized
by: A) the decrease in abundance of the ribs from
the inner whorls to the last one , B) the rapid
attenuation of the lateral nodes and disappearance
of bifurcation, and C) its transversely subrectangular
whorl section.
Me>tlllrements. D Euw H W D{Euw % 0/H %
c-127 24 11 8 9 46 33
COMMENI'S. Acanthohoplites roc hi Breistroffer
(194 7, p. 66: "A can thoplites Mille tianum
D'Orb. r.p. var Sinzowi" Roch, 1926, p. 290, pl.
18, tigs. 1, 1a, 2, 2a; especially fig. 1), has an
ontogenetic development which Is the opposite
to that of the Colombian species: on its early
whorls it has well marked and separated ribs
whose number Increases with growth. From

46 F. ETAYO - SERNA
"Acanthoplites Derognati Roch" (1926, p.
218, pl. 18, fig. 4, 4a) the Colombian species
differs mainly in the whorl section which is hig·
her than wide in the French species and in the
varying strength of the ribs on the venter of
Roch's species, they are uniform or only sporadically
accentuated· on the Colombian species.
OCCURRENCE. Unnamed beds above
the Socota Member and below the Capotes
Member. Upper Aptian.
. Acanthohoelites odiosu§.n. sp.
Pl. 4, fig. 4;Text-figs ER , 5ti.
Holotype. C- 127 (U.N.C.M.H.N.C.P.Ht.36).
Only two specimens are available but neither
shows the innermost whorls. The best preserved
specimen has the earliest portion of the
last whorl depressed, the umbilical wall is subvertical
to rounded and it passes into the adumbllical
half of the convex flank, the adventral
third of the whorl is slightly inclined and the
venter is flattened.
The ornament is divided into prominent
primary ribs and less prominent secondary ribs;
the former are of two types: A) prominent
radial ribs which begin at the umbilical seam (?)
and flare out forming an arc on the adumbilicai
third of the whorl and terminate in a small conical
tubercle, at this tubercle the rib bifurcates,
the adapical branch crosses the venter almost
straight whereas the adoral branch is feebly
arcuate and B) these are thin annular and
parallel ribs between two prominent ribs and
they vary from one to three in number and the
rib _nearest the subsequent adoral primary is
inclin-ed to it as if bifurcating from it.
All ribs converge on the adventral third of
the flank toward the venter as if forming ventrolateral
shoulders, they are arched but adorally
not flattened. Adorally some ribs bifurcate on
the ad umbilical third of the whorl without developing
a tubercle, or a rib can develop an adventral
tubercle without bifurcating, at least on one
flank. These ribs have a tendency to develop a
second tubercle, poorly developed at the umbilical
rim; this gives the ribs a definitely polygonal
profile.
The adapertural segment of these specimens
has a s.o);w.uadrate whorl section with
weak periventral bevelings. There are 35 ribs on
venter of three quarters of the last whorl. The
spacing of the ribs increases adaperturally and
the number of ribs between a pair of emphasised
ribs decreases to one by strengthening of
the other. The ribs have symmetrical slopes and
are rounded. The intercostal spaces are shallow,
almost twice as wJ!ie as the ribs on venter, less
wide on the flank; the ribs do not widen on
venter.
DIAGNOSIS. This is a stout species characterized
by: A) its change in whorl section from
depressed to subquadrate, and B) the strength
of its ornament with flaring ribs on the internal
half of the flank.
Measurements. D Euw H W DfEuw % D/H %
c-127 26 11 10 10 42 38
COMMENTS. This species resembles Gargasiceras
acutecostatum (Riedel} (1938, p.42,
pl.8 1 fig. 1-6, pl. 14, fig. 23) but on the latter
the JUVenile has a subquadrate whorl section but
this is transversely subelliptical on the former;
on Riedel's species the flaring of the ribs accentuates
with growth but the opposite is true in
Acanthohoplites odiosus n. sp. The latter differs
from Acanthohoplites quitasuegno n. S?· by the
less inclined umbilical wall, its section is subrectangular
and its ornamentation is weaker at all
comparable diameters.
OCCURRENCE. Unnamed beds above
the Socota Member and below the Capote&
Member. Upper Aptian.
Acaathob.f:Ute§ olr,ui,Q6tatym n. sp.
Pl. 7, fig. , Tex-fig. 58, 51\
Holotype. C -127 (U.N.C.M.H.N.C.P.Ht.N.37).
Paratype. C • 127 (U.N.C.M.H.N.C.P.Pt.N.37).
The description is based on the holotype.
The part of the phragmocone nearest the pro·
toconch is smooth ; approximately at 2.5 mm
diameter very well marked bullae-like tubercles
develop just adumbilical to the involution line;
these tubercles seem to extend toward the umbilicus
and at about 3 mm diameter the tubercles
are clearly prolongued toward the umbilicus
forming ribs; at this stage the umbilical wall
is convex but there is no umbilical angle and
the umbilical wall grades smoothly into the
convex flank.
The ribs begin at the umbilical seam, they
run straight on the umbilical wall, they form a
slight concavity on the adumbilical third of the
flank and subsequently follow an arc to the
involution line, from that point to the periventral
area they form a concave and finally pro·
ject on venter. As soon as the ribs have beco·
me clearly recognizable they appear like fine,
rounded weak adorally biconcave cords separated
by slightly wider intercostal spaces.
The earliest portion of the conch is ornamented
by primary ribs; shortly after this stage
the ribS" differentiate into primary and intercalary,
the latter tapering and fading out toward
the umbilical walr; these intercalary ribs incline
toward the preceding primary as if bifurcating
from it near the edge of the umbilical wall.
On the adapical portion of the last whorl
(D: 18mm) the ribs are slightly adorally arched
on• venter; they are thin, relatively high and ha·
ve almost symmetrically sloping sides and roun­
.ded tops; on venter and especially when the
shell is preserved the central part of the ador&!
slope of the ribs widens in a visor·like fashion.
Adorally on the last whorl, some primary ribs
have a slight tendency to flare out on the adum-

ZON ATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMM ONITES 47
bilical half of the flank. The ribs have a marked
tendency to appear as primary on one flank and
as a secondary on the other. The whorl section
near the aperture is vertically subelliptical. There
are 62 ribs ori the venter of the last whorl.
. DIAGNOSiS. This species is chararized
by : A) its progressively--steeper umbilical wall
during growth, B) its subovate section and C) its
ornament consisting of fine, numerous, irregu­
larly alternating primary and secondary n'b s
.whose profile varies from feebly flexuous to
biconcave.
Measurement.. D Euw
c - 127 24 10
C-127 19 7
H W D/Euw% . D/H o/o
9 9 42 37
8 8 37 42
NOTE: Width and height give similar values be­
cause· they are approximate.
COMMENTS. This species differs from all
ot:her species here referred to Acanthohoplites
because .of its subovate whorl section and
nuinerous fine ribs.
OCCURRENCE. Unnamed beds above the
Socota Member and below the Capotes Member.
Upper Aptian.
cqnthohoites elegaTJ,{g,Ql l.(f:,n. sp.
l. 5, fig A; ext-fig. 5X.
Holotype; C-127 . (U.N.C.M.H.N.C.P.Ht. N.38)
Paratype. c:121 (U.N.C.M.H.N.C.P. Pt. N.38)
· · · A)Up to 12 mm D (C-127). On this small
specimen the protoconch is visible, it is followed
by the smooth first whorl which has two consqiitions,
, one at the contact with the protocon.ch
·and a second one half the length of the
yolution. The beginning of the second whorl is
Jndlcated by a raised, bullae-like tubercle at the
Jnyolution line; these tubercles (10?) are widely
separated from each other and tend to reach
'fhe umbUical region as weak pleats; on the
tllircJ ·whorl these tubercles disappear and only
Milt, f o ls are present, some of them slighly
,,9re pronunent than the others, but all seem
Jl;) nd at the umbilical wall ; they are rounded
g low:, they are prorsiradiate on the visible
· ·9 the fla,nk; the intercostal spaces are a
Wider thll!l the ribs.
,'.,c·;;:;;,q, the
.
last , whorl (=4th) the ribs are
fi.J!!1' 91Js; they have a convexity on the middle
:d ,p of the ad umbilical thirds of the flank
:#:i :Q.ne ; adoral concavity on the adventrJ
' tli f;lilf(ll·f:he are projected on the venter where
1 . ,Ji!Y;f.;,.,,''{.'fk horl section is rounded, with a
;!1· Yntral . 2!0n (on . the ribs) which tends
·· ' .slightly . ftatned; the flanks are convex
'Plalary nb maY.
o\1!;1¥, the. tunbilical wall is subvertical.
'.;.·
..
·'. o
.
r
toll ow · ·
.. . . . ·
approach e!:,her the
m . .. .. g p nmary
as if bifureating
: : . d qccass10nal!y one of the
.
· secondary
.
.· •. ·,ch.es from, a , Pnmary. Toward the aper­
, Ill· Primary .nbs develop small rounded
tubercles at level of the involution line (adven·
tral third of the flank).
Up to 17 mm D·(C·l27Amore advanced
stage of growth is marked:by a shifting of
the point of initiation of th.,i®ondary ribs to·
ward the middle oftheo,flank;.sdisplacement
occurs progressively ; there may be one or two
intercalary ribs between two primary ribs. The
aperture is retracted on the adumbilical third
of the whorl.
C) Up to 25 mm D (C-127). The orna·
mentation described for the previous stages
consolidates as alternating priJl! ribs which
begin at the umbilical seam describing a conca·
vity, they draw an arc on the central third of
the whorl and draw a faint concavity or follow
almost straight on the adventral third of the
whorl and then extend onto the venter in a
wide arc; at this point the whorl section is
vaulted and the umbilical wall is inclined, the
ribs are finer than the intercostal spaces and the
tubercles disappear. There are 46 ribs on the
last whorl of the largest specimen studied.
DIAGNOSIS. This species is characterized
by: A) the rapid change of the early tuberculate
ornamentation into flexuous ribs, B) its rounded
whorl section and, C) the alternating long
primary ribs and short intercalary ribs.
Measurements 0
C-127 12
C-1 27 17
C-1 27 25
Euw H W DtEuw ",l, DIH%
4 5 5 33 42
7 6 6
10 10 9
41
40
35
40
COMMENTS. This species resembles
Acanthohoplites bigo ti (Seunes) (1887, p. 568,
pl.12, figs. 2a, 2b), and although comparison at
similar diameters can not be made the retention_
of an accentuated ventral flexion to a larger diameter
is apparen t on the specimen illustrated
by Seunes; in general the French species seems
to have a more compressed section than the Co· ·
lombian s p ecies. Jacob (1905, p.412) referred
to Seunes species but did not figure it, so his
comment that at a diameter of 15 mm "certaines
cotes l!!gerement plus accentuees sont bitu·
rew!lees" can not be utilized, though such
phenomenon never occurs in the Colombian
species; likewise the French species, as described
by Seunes, has more numerous ribs.
OCURRENCE. Unnamed beds above the
Socota Member and below the Capotes Member.
Upper Aptian.
_ftS.9JUi.n. sp.
Pl. 5, fig.B; Text-fig. 5W, 5Y.
Holotype. C-127 (U.N.C.M.H.N.C.P. Ht. N.39)
Paratype. C-127 (tt.N.C.M.H.N.C.P.Pt. N.39,40,
41).
A) Up to 18 mm D (C-127). The pro toconch
is followed, after a constriction, by a
smooth whorl. The beginning of the second
whorl is indicated by the appearance of bullaelike
tubercles at level of the involution line.

48 F. ETA YO · ERNA
These tubercles extend rapidly (half a whori Ia·
ter) onto the flank in such a way that the ado·
ral part of the second whorl is covered by raised
sharp ribs that lack any indication of tubercles;
no other indication of tubercles can be obser·
ved subsequently; at this stage the ribs descri·
be an adoral arc on the visible part of the flank;
the umbilical wall is high and rounds smoothly
into the flanks without Conning a shoulder.
The intercostal spaces are channel-like and wider
than the ribs.
On the adoral half of the third whorl the
previously unifonn ribs begin to differentiate
into prominent primary ribs, well defined
externally to the umbilical wall, and intercalary
ribs. A transition zone occurs where pairs of
primary ribs are separated by an intercalary rib.
At the ad apical part of the fourth · whorl an
alternation of primary and secondary ribs is
clearly established, although sporadically two
successive primary ribs may occur. On the last
whorl of the two specimens, the ribs describe a
feeble adoral convexity on the adumbiUcal
third of the flank and the external part of the
umbilical wall, but on the middle and adventral
thirds of the flank they describe a wide concavity
and finally they project in a wide arc on
venter. At that point the intercostal whorl
section is subcircular (H : 6 mm; W: 6 mm), but
the umbilical wall overhangs the previous whorl.
At this stage of the ontogenetic development
the ribs are more widely separated than on the
early horl.
On a group of small specimens it can be
observed that the curvature described by the
ribs on the flank may be more or less accentuated;
the strength of the early tubercles also
varies. On two specimens dissected to the
protoconch the tubercles on the second whorl
at the involution line are in fact periventral
nodes (=coronate whorl): at that stage the
whorl has a convex-concave section beveled on
each side; the third whorl has a transversely
subelliptical section and the fourth a subcircular
to vaulted section; the overlapping of the
whorls extends only to the periventral !Ilargin
of the preceding whorl.
B) Up' to 50 mm D (C-127). On this spe·
cimen the protoconch and early whorls can be
observed although the initial ornament is weak;
the development of the ornamentation follows
the same pattern described for the smaller specimens;
on the last preserved whorl the whorl
section is higher than wide with the maximun
inflation near the:adumbilical third of the flank.
The ribs are high with steep sides and sharp
tops, the intercostal spaces are at least one and
a half times . wide as th ibs; the ribs are
slightly flexuh .e flank and they extend
onto venter ir( li)load but slightly pointed arc.
On venter all rll5s a're of equal strength and are
not thickened. Sporadically one rib may bifurcate
. from the adventral third of a preceding
primary but no tubercles develop; the primary
ribs have a faint tendency to flare out periven·
trally.
C) Up to 125 mm D (C-127). Or. this specimen
the early whorls are observable and they
are similar to those of the previous specimens.
On the last whorl the ornament changes, the
ribs widen and become rounded and the secondary
ribs tend to connect more frequently with
the primary ribs near the boundary between
the middle and the adumbilical thirds of the
flank, or sometimes at the umbilical margin.
The primary ribs reach the umbilical seam and
are prominent on the periumbilical rim; they
have a straight to feeble sinuous profile; they
describe a clear concavity on the umbilical rim
and a broad slightly projecting arc on venter.
DIAGNOSIS. This species is characterized
by A) the transitory tuberculate stage of the
early whorls, B) the young adults with acute,
high, feebly falcifonn primary ribs which alternate
with one or two intercalary ribs begining
near the middle of the flank, C) the mature
adults have broad primary ribs which become
very prominent at the umbilical rim and bifurcate
near the middle of the flarik, and D) the
changes in whorl section from rounded to subrectangular.
Measurements D Euw H w D/Euw D/H No. R.
% % +
C·127 lEi 6 6 6 40 40 42 ?.
C·127 l6 6 6 6 37 37 50?
C-127 17 7 7 6 41 41 46
C-127 18 7 7 6 39 39 48
C-127 50 23 18 17 46 36 46 +
C-127 126? 46 50 40 7 7 60 7
COMMENTS. This species resembles to
"Parahoplites obliquum" Riedel [1938, pl.6,
fig. 11-12; see also under Riedelites herein),
particularly when the inner whorls of the former
are considered ; on Riedel's species the ribs
become conspicuously quadrate in section on
venter but in this new species the ribs are
rounded on venter or develop a visor-like projection
on the ventral median line.
OCCURRENCE. Unnamed beds above
the Socota Member and below the Capotes
Member. Upper Aptian.
This species is named in honor of the late
geologist Luis A. Perez, Universidad Nacional
de Colombia.
_A£aat!JohoDli.te.. (?ll.e.Jltacs:.rati[Qc:mg n.sp.
Pl.7, fig.4; Text-fig. 58.
Holotype. C-127 (U.N.C.M.H.N.C.P.Ht.N.40).
Only one specimen is available. The conch
is evolute; the nuclear whorls have been dissolved
away; ·on the second whorl the ornamentation
is alrei@y' . visible · ,and characterized by .cq
and well • elevated flaring ribs, of which one or
two are' less elevated and appear like intercalary
ribs between primary ribs. On the third whorl
the ribs begin on the .wnbilical wall describing
a feeble concavity, then they fonn an adorai.
arc on the visible part of the flank.

ZON ATION OF THE CRETACEOUS OF CENTRAL COLOMDIA BY AMMONITES 49
The intercostal spaces are channel-like,
.;,ider than the ribs. On the last whorl the ribs
are very prominent. On the last third of the last
whorl, the primary · ribs develop a blunt tuber·
cle approximately at the boundary between the
middle and the adventral thirds of the flank.
(:;=involution line),and ati.that point the primary
ribs bifurcate. F'rom the tubercle to the peri·
ventral margin the ribs are clearly beveled; at
the periphery the ribs are raised in to slight
hurnps and then are depressed at the ventral
median line . The secondary ribs have the same
changes but weakly developed.
The intercostal whorl section is circular.
The umbilical wall is continuous with the flank
throughout all the stages of growth and there is
no thickening of the ribs on venter. The inter·
costal spaces-tend to widen toward the aperture.
There are. 36 ribs on the venter of the last whorl
of this specimen.
DIAGNOSIS. This species is characterized
by: A) its whorls barely in contact, B) the acute
and flaring ribs, separated by wide, channel like
intercostal spaces, and C) the adventral beveling
and median ventral depression of the ribs.
Measurements. 0 Euw H W 0/Euw % 0/H%
c . 127 30? 13 9 ? ? ?
COMMENTS. At first glance a comparable
species is "lloplites Ruspolii Mayer Eymar"
(1893, p. 258, pl. 2, figs. 10·11) from Somali·
land, but.this species has a much more compre·
ssed whod•section, higher than wide, a more
trongly beveled periventral area with a very
'narrow median ventral zone, however the type
of ribbing appears similar. Collignon (1962, p.
'l.i fig. 1027} figured as "Colo mbiceras sp. aff.
caucasicum Lupp." a specimen which slightly
i'e rnbles the Colombian species but it lacks
tile periventral elevation of the ribs and the
pressed ventral median line.
.-=· ·::. _
..
.
·
OCCURRENCE. Unnamed beds above
the Spcota Member and below the Capotes
Mrnber. Upper Aptian.
:? ... : . , Pl. 3, fig: 3; Text-ng. 5o.
.•. •· A · c.· «nth . dh . oplites L'?l s:pe'Jli[Or'!J n. sp.
tt?l?type. G l27 (U.-N.C.M.H.N.C.P.Ht.N.4 1).
:)";.-Jialf a small . specimen with the proto­
:c:mc prnsery-:d. At th beginning of the
ec·o
..•. d wh
orl
tiny ullae-hke tubercles appear
i:ttlpedlately adumbiiical to th.e involution line;
Jt?; tl_t ese tuercles faint pleats extend t.o the
· -
..mh,IUcal .am; at . the inception of the third
W,.pd noticeable ribs are present, and some of
J.llQ1 have_a spine-like tubercle at point where
:: .f()Uomg whorl begins. The ribs are cute
-!.·!;l .. ,j;he mtercostal spaces are at least twice as
;.-·:·-p()radically. one rib becomes more pro­
'1\'lP:e. as the nbs;
.
:-b· · ··.·.1•f':.,.n. ·n'and.fan()t{ter _nb inc . lines toward it as if
· . .
lJ.l rca ng ron · •t b · .

50
.,CQ.IQmQ.ik.er::fJ§. W forg.ro.t, n. sp.
Pl.6, fig.13; Text-figs. 6A, 6B, 6D.
1938 Colombiceras aff. tobleri Jacob, Riedel,
p.51, pl.8, figs.23·24, pl.14, f-7.
1949 Colombiceras aff. C. tobleri (Jacob),
Humphrey, p. 151.
?1954 Colombiceras aff. tobleri (Jacob), BUrgi,
p. 17.
1957 Colombiceras aff. tobleri Jacob, Biirgl,
p. 135.
1957 Colombiceras nov. spec., Btirl, pl.8,
fig. 2, "specimen HB2327/1' ; recte
HB2327/2, X 8/10.
1964 Colombiceras aff. tobleri Jacob, Etayo·
Serna, p. 119, pars.
1965 Colombiceras aff. tobleri Jacob, Biirgl,
in Campbell and Biirgl.
Lectotype, Here designated, the specimen figured
by Riedel, 1938, p. 51, pl.8,
figs. 23-24, pl. 14, fig. 27.
Paratype. The second specimen referred to by
Riedel, 1938, p.51, M.G.N. Pal. 020.
Hypotype. (U.N.C.M.H.N.C.P. Hy. N.8,9,10).
A) Up to 20 mm D (C-200·1,2,4). The
innermost whorl observed (3rd'?) is coronati·
fonn, with its maximum width toward the cen·
ter of the whorl side; there is a continuous roun·
ding of the intercostal whorl section; the umbi·
lical wall is short and vertical. There are groups
of annular well raised ribs that begin at the umbilical
seam, they are sharp on the flank but
tend to flatten and widen on venter; adapically
these groups of ribs are separated from each
other by a deep channel-like constriction and
adorally by a prominent, slightly thicker and
flanging rib which at the level of the line of involution
develops an acute node from which
another rib branches to join a similar tubercle
on the opposite side, these ribs appear always
immediately adapical to the constriction; at this
stage the intercostal spaces are one and a half ti·
mes wider th the ribs.
These groups of ribs consist of five, four,
three or two ribs, in decreasing order from the
adapical to the adoral part of the shell, but the
pattern seem

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 51
? 1957 Co lombiceras nov. sp. aff. tobleri (Jacob),
·
. BUrgi, pl .8, fig. 6a, 6b, "specimen 666",
rect. x 8/10.
Holotype. C-5 13 (U.N.C.M.H.N.C.P.Ht. N.42)
p aratype. C-5 13 (U.N.C.M.H.N.C.P.Pt.N.42,43)
. The whorl section ts depressed in e ear­
ly juvenile it is rounded subquadrangular m the
later whoris. In the juvenile the umbilical wall is
vertical, short, it rounds sl!loothly into _the sligb·
tly convex flank, the penventral margm rous
evenlY into the venter. In the adult the umblh­
cal wall is inclined.
·on the adult, the ornament consists of
strong primary ribs which flare out on the
flank· they are concave on the umbilical wall and
make' an adoral arc on the adumbilical and
middle thirds.of the flank, they then cross the
venter straight, but the general appearance
of their outline is as if they were rursiradiate.
on the. adventral fourth of the flank and on the
. venter the ribs are flattened. The primary ribs
begin at middle of the umbilic wall r a the
umbilical seam; the secondary nbs begm etther
Independently at the periumbilical margin or
. "adjoining" the subsequent primary rib ; at the
periventral region some of the primary ribs
develop .a small to medium size tubercle from
which; usually but not always, a secondary rib
branche. and crosses the venter to join a similar
tiJ.bercle on the opposite side; sometimes the
priary d secondary ribs apparently coalesce
giving a very broad section to the venter, the
tubercle, however, persists.
Usually there is only one long secondary
rib but s()metimes two are present. With growth
the primary . and secondary ribs regularly alterqate
. On the flank the Intercostal spaces are
.. deep and wider than the ribs but subequill to
them on venter.
. . DIAGNOSIS. This species is characteri·
zed by: A) its stocky build, B) its rounded sub·
quadrate whorl section, C) its wide umbilicus,
and J?) Its moderate size and regular illtemation
of pnmary and secondary ribs on the adult.
. Mei.lunmellta.
0 · 220 1.
C2.20 - 2
C-U0·3
C·220 -4
D
36
23
28?
197
Euw H
17 12
11 ' 9
14 10
8 7
w D{Euw 0/H No.R.
% %
12 47 33 17(2/3)
9? 48 39 26(3/4)
11 60? 36? 18(1/2)
7 42? 37? 38?
. . · . ·· . ,POI\IIMENTS. This species was illustrated
b(Z !lurgl as Co lombiceras nov. sp. aff. tobleri
· . R o.> . (Biirgl, 1957, pl.8, fig. 6), Likewise
1e e .(1938, p. 46, pl. 12, fig. S) recorded
,.
·· . A.canthoplites aff. abichi Anth." from "Ha-
cienda Magdalena, al Este de Viota", a Iocillity
'\'(here_ .the .same unit as that from which my
ln1tenal has been collected crops out "Parah o­
4bb, 2 t97
P ltes abichi Anthula" (1899, p. 118, pl. 9, figs.
_
· stion
g n\b ..
type speCies of Pro tacanthoplites,
01l • has irregularly spaced ribs with
rcates, · along the lme of mvolution , the
. bifu · · · . rc es from hich seconary rib
Russian species also lacks the regular adult
alternation of primary and secondary ribs of
the Colombian species. The new species also has
some ree'T'hlance to ''Acanthoplitespotreritense
Humphrey" (1949, p. 139, pl. 12, figs. 11·12),
but the Mexican species is more closely costate,
is compressed and has a median yeqtral depression
of the ribs as in Gargasiceras Casey {1954).
OCCURRENCE. Paja Formation (Arcillolitas
abigarradas. Segment E). Socota Member.
Upper Aptian.
This species is named is honor of Dr. Alberto
Sanniento A., former Director of the
Servicio Geologico Nacional (1961-1964).
ca;;;:s-' (Gargasicergc:;;:"1954.-]
Gargasiceras Casey, 1954, pp. 114.
TYPE SPECIES. Ammonites gargasensis d'Orbigny,
original designation.
Garf:icer interiectum (Riedel).
PI. , fig. 5, Text-fig. 61. ·
1938 Acan thoplites in teriectus Riedel, p. 41,
pl. 8, figs. 8-10, pl. 14, fig. 22.
1954 Gargasiceras interiectum Riedel, Casey
p. 114.
?1954 Acanthohoplites in teriectus Riedel, Biirgl
p. 17.
? 1955 Acanthohoplites in teriectus Riedei,Biirgl
p. 12.
? 1957 Acanthohoplites in teriectus Riede Biirgl
p. 135 .
1964 Acanthohoplites in teriectus (Riedel),Eta·
yo Serna, p. 119, pars.
1965 Acanthohoplites in teriectus Riedel,Bilrgl
in Campbell and BUrgi.
Lectotype. Here designated, the specimen illustrated
by Riedel, 1938, pl. 8, fig.lO
(S.G.N.Pal. 0310).
Hypotypes.ta Ye (U.N.C.M.H.N.C.P.Hy.N.11.
12).
Type locality. Barichara-Sube (Santander).
A) Up to 17 mm D (La YeJ . The earliest
nuclear whorls studied have a w1dely rounded
venter, the whorl section is wider than high and
does not show a defined periventral angle; the
ornament consists of well defined flexuous
growth striae which are narrower than the inter
spaces between them. This non-ribbed stage is
followed by the sudden development of a rib
bearing a bullae-like tubercle rLa Ye-2-bis], approximately
at center of the ftailk, from which
two flattened ribs fork which are slightly depressed
along the ventral median line; the adaplcal
rib is itself divided longitudinally by a cieft so
as to form two individual riblets.

52
Among the subsequent flared ribs some
of them develop minute tubercles at the level of
the line of involution. On the venter the ribs are
more distinct, due to the fact that their adapi·
cal side is vertical but their adoral side is incli·
ned. The adapical whorl section of the same spe·
cimen, at a diameter of 16mm is almost circular
(H:4; W: 4mm) butadorally it has already begun
to fonn a broadly rounded periventral margin.
There is a rather high and steep umbilical wall.
The primary ribs begin at the umbilical
seam as raised lines, they describe an adoral
concavity to the periumbilical margin and from
there to just beyond the middle of the flank the
ribs describe an adoral convexity and then an
adoral concavity on the adventral third of the
flank. The intercalry ribs begin at the boundary
between the adumbilical and the middle thirds
of the flank or near the lateral tubercle.
B) Up to 33 mm D [La Ye-5-bisl. On the
ad apical preserved portio ;'\ ' he last wh orl two
types of ribs are present: one type begins at
middle of the umbilical wall and describes an
adoral concavity to the beginning of the middle
third of the flank, then they describe an adoral
convexity on the middle third, and adventrally
the ribs describe a shallow lid oral concavity.
Some of the ribs bifurcate near the boundary
between the middle and adumbilical thirds of
the flank, or more frequently at the boundary
between the middle and adventral thirds of the
whorl and have a tendency to develop a minute
tubercle there; the other type of ribs begins as
fine threads near the umbilical rim, trend simi·
larly to the others and slowly increase in size
towards venter where all the ribs have a similar
width and are separated by wider intercostal
spaces,
· . . DIAGNOSIS. This species is characterized
by: ·A) a rather long smooth stage (with cons·
trictions?), B) a longer juvenile stage with nume·
rous sigmoidal ribs, and C) a mature stage with
mostly non tuberculate ribs with an alternation
of primary and intercalary ribs, with a tendency
for dominance of the primary over the intercalary
ribs adaperturally.
Measurements. D Euw H w D/Euw D{H No,R.
% %
La-Ye·2·bls 17 6 7 7 6 36 417 30(1/2)
La-Ye·3-bls 17 67 ? ? ? 417 ?
La-Ye-6-bls 28 10 10 11 36 36 30(1 /2)
La•Ye-5-bls 33 14 13 14 42 39 30(1/2)
cm.l.ll\1EKTS. This species differs from
qargasiceras pliJc'J;fp JRiedel) by te oval sections
of tile lahte tile fQmler has a
rounded subquadrite one. In G. pulcher (Riedel)
the bifurcation of the ribs occurs regularly near
tile middle of the flank and at similar diameters
the ornament of prominent bifurcating ribs is
still present but the opposite is true for G. interiectum.
OCCURRENCE. Socota Member. Upper
Aptian.
F. ETA YO - SERNA
Gargasiceras interiectum (Riedel)
(Morph I)
Pl. 6, fig. 8; Text-fig. 6H.
Hypotype. La-Ye-4-bis (U.N.C.M.H.N.C.P.N.13)
A) Up to 13 mm D [La-Ye-0]. The adapical
half of the last whorl appears smooth but it
is covered by fine , low flexuous riblets, they
cross the venter uninterruptedly; the ribbing
becomes prominent rather abruptly on the ado·
ral half of the whorl; the ribs start at the umbi·
lical seam and make a delicate biconcave arc to
tile venter, they flare out on the adumbilical
third of the flank and are sharp; on the adventral
third of the flank they are flattened and
on the venter a bit wider and slightly depressed
along the median ventral line. One of the early
ribs has a weak tubercle at level of the involu·
tion line where tile rib trifurcates but on the
other flank no tubercle is developed and th e rib
only appears broader. An alternation of long
primary ribs and shorter intercalary ribs begins
almost contemporaneously with the appearence
of the ribbing.
B) Up to 40 mm D [La-Ye-4-bis]. The
whorl section is subrectangular and has broadly
rounded periventral margins and feebly arched
venter; the ornament consists of long primary
ribs which begin near the umbilical rim, these
ribs develop a flange on the ad umbilical third of
the flank, they are high and sharp; the intercalary
ribs begin at the boundary between the ad umbilical
and the central thirds of the flank. All the
ribs become flat topped and slightly broader on
the adventral fourth of the flank and venter, they
have vertical sides; the intercostal spaces are
twice as wide as the ribs on the internal mold.
The umbilical wall is short and subvertical.
NOTE: This morph has a well defined altema·
tion of primary and intercalary ribs on
venter and the subrectangular section
seems constant throughout the ontoge­
ny.
Measurements
La·Ye-D·bill
La-Ye·4-bls
D Euw H W D{Euw
%
13 6 6 6 46
40? ? 14 14 ?
D/H No.R
%
38 16(1{3)
36? 23(1/2)
COMMENTS. This species differs from
Riedel's "Acanthoplites in teriectus ", as he illus·
trated it where the inception of tile intercalary
ribs is on the adventral third of the flank. This,
however, could be a a matter of preservation.
However-, the ribs are distinctly more flattened
.in "mQIJ?;NJ.'! tlum on Riedel's specime. Rie!fej: :
remark '(1938, ·pAl): 1'En esta espec1e no hay:
bifurcacion de costillas ni fonnacion de tuberculos"
as here understood indicates that the tu·
berculate stage is a transient one terminated very
early in the ontogeny as pointed out by Casey
(1954, p. 114); it Jll!ISt be added that the
ventral depression (bu-t not interruption) of
the ribs along the ventral median line is another
transient characteristic.

ZON ATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 53
OCCURRENCE. Socota Mmber:; Upper
Aptian. . . ··
Gargasiceras 'i&{cher: (Riedel)1
orph I)
1938 Acanthoplites pulcher Riedel, 1938,
c
p.43, pi.S, figs. 11-14.
?1954 Parahoplites cf. pulcher Riedel, Biitgl,
pl.17.
1954 G. [a&asiceras] pulcher (Riedel), Casey,
114.
1964 Parahoplites pulcher {Riedel), Etayo-Ser­
na, p. 119.
1965 Acanthohoplites pulcher Riedel, Biirgl,
in Biirgl and Campbell.
L6ctotype. Here designated, the specimen illus-
•. -.•. _.... · trated by Riedel, 1938, pl. 8, figs.
·. . ... 11,12,13,
}'aratype. Riedel's pi.S, fig.14, S.G.N. Pal.0310
Hypoty.pe. La"Ye-7-bis (U.N.C.M.H.N.C.P. Hy.
N.14). ·
"morph" resembles
fptu_cller. ·tl'l.le(letJ, which WllS des­
extem.n • • • anchamen­
the _latter differs
section is oval.
well defined, rounded #"ff; ·--er than the intercostal
spaces. The pnmaty.'bs are very pro·
minent 11nd hcome well define;: at the external
margin of the umbilical wall.
On the adoral half of the third whorl the
number of intercalary ribs decreases from two
to one; on the last preserved whorl there are
alternating primary and secondary ribs. The
whorl section is subrectangular with slab-like
sides and rounded venter, the umbillcal wall is
inclined and merges smoothly into the flank.
On the adoral third of the last preserved whorl
the intercalary ribs disappear and the resulting
intercostal distance is five times as wide as the
ribs. The apertural margin is plain.
DIAGNOSIS. This species is characterized
by: A) the progressive ontogenetic elimination
of the intercalary ribs, B) the subrectangular
slab-sided and rounded venter whorl section
and C) the adorally arcuate . trend of the ribs
on the flanks .
Measurements D Euw H W DfEuw% D/H %
C·151 29 13 11 10 45 38
COMMENTS. This species resembles "Parahoplites
abichi Anthula, 1899" rtype species
of Pro tacanthoplites Tobvina, 1970 J, but on
the latter genus as interpreted by Tobvina (English
trans., 1971, p. 338) "Sections of whorls
transverse-oval, tumid or practically subquadra·
te, width invariably exceeding height.", furthermore
the primary ribs bifurcate from the lateral
tubercles, character'.stics that are absent from
the Colombian species; the Russian and the Colombian
species have in common, however, the
broad umbilicus and the tendency of the ribs
to flatten on venter "to varying degrees" (Tob·
vina, op. cit., p. 338); the Caucasian species has
constrictions that are also absent from this species.
Colombiceras crassicostatum {d'Orbigny)
(1841, pl.59, fig. 1·5) has only tiny lateral
tubercles and its ribs are wedge shaped on the
flank.
"Hypacanthoplites ? rursiradiatus Humphrey"
(1949, p.142, pl. 14, figs. 11, 12) l type
species of Pegnaceras Cantu-Chapa (1963J, is a
species on which "all ribs thicken in transversely
elongate swellings" (Humphrey, op.cit., p.
142) a characteristic not observed on G. juanwyatti.
One specimen that has some resemblance
to the present species but which has intercalary
ribs to a larger diameter than in the present species
was figured by R. Douvilllt (1906, p.147,
note, pl. 1, fig. 3) as Pedioceras or a new genus
from an unspecified locality in Colombia.
OCCURRENCE.Upper Aptian.
This species is named in honor of Profes·
sor John Wyatt Durham.
Genus

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 55
1976 Douvilleiceros mammilla tum (Schlotheim),
Etayo-Serna et al, p. 227.
1916 Douvilleiceras aff. mammillatum (Schlo­
theim), Etayo-Sema et al, p.225, tab. 2.
Holope. .(;8 (U .N.G.M.H.N .C.P.Ht.N .44 ) .
PiiitYifl.! . (U.N.C.M.H.N.C.P.Pt.44,45).
Two collections (C-13 and P-21B) have
been studied and it is considered tfiat the spe­
cbnens axe conspecific. In my opinion these
specimens overlap in the development of the
omament.
A) Up to 15 mm D [C-218). The earliest
omament observed on the adapical portion of
"this specimen consists of widely spaced fold·like
ribs which describe a bend from the umbilical
margin to the middle of the flank, at which
point there is a spine like tubercle , the ribs des·
cribe a fe eble adoral concavity and extend onto
venter. A transversely elongated inflation is pre­
sent on both sides of the ventral median zone.
At the adoral end of this specimen (D: 15mm]
a small tubercle is present on the nbs at their
periumbilical margin and the ventral tubercle
beeomesmammiform, but no indication of any
division of the ribs is obsenrable on the ventral
· tubercles. The intercostal growth lines have a
profile similar to that of the ribs. The whorls
Qrt! depres&ed. No clear indication of the ventral
tubercles appear before a diameter of 24mm.
_ B) Up to about 35 mm D [C-218]. The
omament is stronger but In the previous pattern
e ribs are widelf spaced and a weak annular
iritercalm:y rib, aliriost imperceptible on the in·
· :temal mold, occurs midway between the primacy
. ·- .Jibs I:rnpressions left ··on - the umbilical wall of
ttre: subsequent volu tions indicate that at this
point the lateral tutlercles represent the base of
long _ spines, directed adapically. About 30 mm
- dieter a tiny· tubercle appears on test exter·
!:laJIY to the periumbilical tubercle but it seeming­
does not leave any indication on the lnamal
Qld at this stage.
_ d C) Up. to 45 mm D [C·13J. A single speci­
>lllen Qn which the Internal whorls can not be
.!!died._ The first rib visible on the ad apical por­
·tls»n of the ·last whorl arises near the external
·'Part of the umbilical wall and has a minute tu·
: rcle at the P ! riumbilical rim; slightly adven­
\ :ersely _ elongated node is present and on
JIJIIY to the middle of the flank a prominent
>b.o sldes of venter well marked tubercles are

56
A) Up to 18 mm D [ C-215-21 ]. To this
diameter the internal whorls have not been ob·
served. The adapicalmost part of the last preserved
whorl has a subpolygonal·renifonn intercos·
tal whorl section: a rather abrupt umbilical wan
which rounds smoothly into the flank; the ad·
ventral segment of the flank is broadly rounded,
the venter is narrow with a flat ventral median
band.
The ornament consists aflaw flattened ribs
which begin at the umbilical margin and bear a
rhomboidal prominent tubercle that is spirally
elongated. From this tubercle to the periventral
margin the ribs broaden and become depressed;
along both sides of the ventral median band the
ribs develop radially elongated crest-like t,uber·
cles; on midventer the ribs are depressed, al·
most obliterated but have a tendency to split
transversely. Sporadically an intercalary rib
may develop, it begins at level of the lateral
tubercle and branches from a strong primary ri
this secondary rib has only ventrolateral tuber·
cles: it is so obscure on venter that the tubercles
appear as if they were independently arising
from the test.
The intercostal space between the primary
ribs is very wide, up to two and a half times the
width of the primary ribs except when an in·
tercalary rib is present; this interval is covere.d
by wen marked growth lines which are adorally
concave on the umbilical wall. Towards the
adora1 half of the last whorl the lateral tubercle
occupies a medial position on the flank and
small conical tubercles appear on the ribs at the
periumbilical margin.
. B) Up to approximately 25 mm D [C-215·
22]. At about a diameter of 20 mm the spirally
elorigated periventral tubercle acquires a mammi·
Dated. shape, and contemporaneously these tu·
bercles develop adumbilically an incipient tuber·
cle that with subsequent growth tends to match
the adventral one in prominence. The spacing
between the upper and lower ventrolateral tu·
bercles varies. The lateral tubercle increases in
size and develops a large circular base. At this
stage the intercostal whorl section has a broadly
flattened to slightly arched venter which rounds
Into the flattened flank; the umbilical wall Is
oblique, the periventral tubercles are slight
bumps on the test and they rarely show on the
internal mold.--en the last rib preserved of this
specimen there is a faint swellin between the
centro-lateral and . the periumbihcal tubercles.
C) Up to 95 mm D [C-215·251. Lacking
any in tennediates I am interpreting this speci·
men as conspecific with the previously descri·
bed specimens, based on their apparent simUa·
rity. At this stage of growth the ribs are thin,
high, with rounded top and separated by wide
intercostal spaces. The ribs begin at the exter·
nal part of the oblique umbilical wall as elonga·
ted and flattend lozenge-like subdued elevations.
The ribs are slightly convex adorally on flank
8lld althoul!h a bit wider on venter their width
on the fl8lllts is ve:ry uniform. On the adapical
F. ETAYO ·SERNA
half of the last preserved whorl there are five
tubercles on each side appearing like symmetri·
cal ripples on top of the ribs, and distributed as
follows: one ventral slightly elevated and rna·
mmillated tubercle, one on center of the ventral
shoulder, another on the rim of the ventral sho·
ulder, a tubercle in the middle of the flank and
one adumbilical tubercle. The lateral tubercles
are equidistant from the one at the middle of the
flank. Toward the aperture there is a progressive
development of another tubercle close to the
ventral median line in such a way that the ini·
tial ventral sulcus almost disappears; although
there is an increase in size of the tubercles from
the umbilical to the ventral, in general the tubercles
tend to have a uniform size • . There are
30 ribs on 3/4 ths of the length of the 'last whorl;
the living chamber occupies half of the last whorl
DIAGNOSIS. This species is characterized
by: A) the development of a delicate tubercula·
tion of the ribs which appear sllgh tly undulated
in longitudinal profile, B) the rounded-subquadrangular
whorl section, and C) the very shallow
and narrow ventral median sulcus in the adult.
Meuurementa. D
C•215 ·21 18
c. 215 . 22 26
c. 21 5 - 24 95?
Euw H W D/Euw % D{H%
9 ? ? 50 ?
11 10 12 44 40
46 ? ? ? ?
COMMENTS. The specimen figured by
Collignon (1963, p. 112, fig. 1243) as Douvilleiceras
albeme Spath, has a similarly reduced
median ventral sulcus but its tubercles are cle·
arly clavate and its ribs arise in pdirs from
accentuated periumbilical tubercles, the two
latter features are absent from the Colombian
species. The specimen described by Riedel
(1938, p. 32, pl.6, fig. 6,7) as "Douvilleiceras
monile Sow", and excluded from the scope of
Sowerby's species by Casey (1962 p. 288),
resembles Douvilleiceras abozagloi n. sp. in the
loss of the ventral sulcus and its rounded venter,
but on Riedel's figured specimen the rib·
bing is coarser and the inner lateral tubercles
postulous. The specimen (U.S.G.S.No.23836)
identified by Imlay as "Douvilleiceres aff. D.
monile (Sow.)" from locality Santa Rosita I,
Venezuela (in Rod and Mayne, 1954, p. 267),
from examination of a plaster cast, seems to
belong to a related species; it has wider ribs and
longer and better stressed clavi, further the ven·
tral median sulcus is persistently wider than in
the Colombian species.
Douvilleiceras solitae (d'Orbigny) has a
more persistent and deeper ventral median sul·
cus, the ribs are broader and the ventrolateral
tubercles larger than in D. abozagloi.
OCCURRENCE. Lower Albian.
• This species is nemed in honor of the geo·
logist Jacob Abozaglo M.
\, _ .. ...
_
]""""
u_- --·-
. Ql100
.. ras-.
. . ,_.""'\'}!!2;
Eodouuilleiceras Casey, 1961, p. 191.

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 57
TYPE SPECIES. Douvilleiceras horridum Rie­
del, original designation.
-Jt o 'fi il fj(:T s trf e d&Q,a'if&.l!lb_E_:_.P·
• , 1g. , ex 1gs. , .
1961 Douvilleiceras horridum Riedel, BUrgi, p.
5 ex (U.N.C.M.H.N.C.P.N.1843).
1964 Douvilleiceras horridum Riedel, Etayo­
-"'•
Sema, p.120 pars ex Btirgl 1961a.
1976 Eodouvilleiceras horridum (Riedel), Eta­
.
yo-Sema et al, p.225, tab.2, p.227, ex
(U.N.CM.H.N.C.P.N.1843).
Holotype. C-170 (U.N.C.M.H.N.C.P. Ht. N.46).
Only one specimen is available; the innermqst
whorls are not observable. On the 3rd (?)
h.orl of the phragmocone prominent spines
develop about the middle of the flank and the
horl appears coronate ; the ribs they surmount
Wide and low and start at the umbilical rim;
tOw-ard the adapical portion of the following
whorl, tiny conical tubercles develop at the periumbilical
end of the primary ribs. The umbillea(
wall Is rounded, subvertical and merges gradually
into the flank. The intercostal spaces are
wide, variable in with, one and a half or t'vo times
as wide as the ribs.
The intercalary ribs occur at irregular inteiVal.s,
they have only centrolateral and perivel).tnd
tubercles, and appear like slight folds of
tile test. On the primary ribs ventrolateral tubercles
enl&rge into strong bosses which bear a
parallel,lower and slightly indicated clavus. The
whorl section has a rounded, lozenge-like shape.
•. . .
. .
· .. . DIAGNOSIS. This species is characterized
y: A)Jts compressed shape and its lozenge sha­
ped whorl section, B) the accentuation of the
ventral tubercles which defme a prominent U­
!lped sulcus, and C) the feeble development
.of' the intercalary ribs.
Mameu.t.. D Euw H W D/Euw % D{H %
C·170 "0 211 18 22 110 36
CC?ENTS. This species differs from
odouurllerceras honidum {Riedel), which has a
sJower accentuation of the tuberculations, broa­
Whorl section and wider and shallower ven­
mte su al
lcus than In E. pedrocarvajali, finally the
··· . n: ary ribs persist longer.
fi 261; Text-fig. 90) u "E. horridum (Riedel),
>'" · 'I'h,e specimen Illustrated by Casey (1962,
o:&er ptian, near Bogota, Colombian (Umv.
CiUv no.C-1563)" is more like E. pedro­
RiedQJf!1
than llke Riedel's species. Both
e 8 species and asey's fip1red spP.imen 'l9381UlY3tr!,!f8Phlc lilclt
mformation (see R1edel,
es):, P· ; llllK1 Univ. California, Mus. Paleont.,
Biirf (1961) recorded as occurring
together 'Douvilleiceras mammillatum (Schlo·
theim)" ::! "nouvilleiceras horridum Riedel",
from Ortega (Depto. Tolima); see synonymy.
OCCURRENCE. Lower A!_Pian.
This species is named in honor of the late
geologist Pe dro Carvajal •
. Eoduv i llejcerp.s i? · t j{ uendamai. n. sp.
. 't'ext· gs. 6 ,60,13. · -
Holotype. C-233 (U.N.CM.H.N.C.P.Ht. N.47)
Paratype. C-223 (U.N.C.M.H.N.C.P.Pt. N.47,48)
A) Up to 26 mm D (C-223-17). On the
innermost whorl observed (2nd of the phrag·
mocone) there are long spines along the involution
line; short and long srines alternate in a w
pattern; the impression o the spines is visible
on the dorsal part of the following whorl as depressed
furrows. The long spines arise from wi·
de ribs that reach the umbilical rim, but the
intercalary rib corresponding to the short spine
disappears without reaching the umbilical rim.
The third whorl has a high and vertical
umbilical wall which rounds abruptly into the
convex flank; the adapical portion ofthe fourth
whorl has ribs that bear a small conical tubercle
at the umbilical rim. The ribs appear like prorsi·
radiate blunt folds: the portion of the ribs
between the umbilical and the lateral nodes has
the shape of an isosceles triangle; from the
centrolateral tubercle to the ventral tubercle
the ribs are wide and have subparallel sides,
they tend to cleave longitudinally along their
central axis. In middle of venter the ribs are
wide and depressed. The intercostal spaces are
approximately one and a half as wide as the ribs
on the flank but twice as wide on venter.
At the umbilical rim the tubercles are
tiny, and elongated in the direction of the ribs;
the ventrolateral tubercles have an elliptical
section elongated in the direction of coiling but
a subcircular section Is also common. The
wth lines may be so accentuated as to give
the impression of being Intercalary ribs.
B) Up to 48 mm D (C-223). With increa·
sing diameter there is a tendency for the ribs to
increase their wi:ith without a corresponding in·
crease In height. An accentuation of the periventral
tubercles occurs on the living chamber
for two thirds of the length of the last whorl.
Toward the apertural segment. of the last preserved
whorl the tubercles attenuate; the ventrolateral
tubercle becomes compressed, bullae·
llke. The last rib is thin, barely visible with only
lateral and umbilical conical spines aiid without
ventral tubercles. The apertual margin is plain.
DL\GNOSIS. This species is characterized
by: A) Its very depreed whorl section, B) the
inconspicuous bullate periumbilical tubercles,
the long periventral spines and the hom llke
ventral tubercles, C) the dominance from early
In the ontogeny of the primary ribs 'With almost

58 F. ETA YO · SERNA
no intercalary ribs, and D) the lack of bifur·
cation of the primary ribs and their offset longi·
tudinal prome.
MeUUftmenta D Euw H w D/Euw DfH No.R.
% %
C·223·17 26 12 11 17 48 42 12
C·223·18 ao 13 12 20 43 40 13
C•223·19 22 12 8 17 0 36 12
C·223·20 2& 12 11 1& 48 44 137
C·223·21 48 23 19 27 48 39 16
COMMENTS. This species resembles
Eodouvilleicerus horridum (Riedel) (1938, p.29,
pl.6, figs. 1,2, pl.14, fig. 11), but on the latter
at the equivalent diameter the lateral tubercles
are leas developed and the intercostal distance is
greater; in Riedel's species the ventral tubercles
tend to develop an additional tubercle early In
the ontogeny (see lower right of figure 2 of
. plate 6 of his paper), he noted, however,
that because of the poor state of preservation
of his specimen, the inital appearance of divi·
· ded external nodes could not be determined.
Eodouvilleicerus (?) tequendamai differs
from Cheloniceras (Epicheloniceras) barreroi n.
sp., by the ribs bifurcating from the centrolate·
ral tubercles and the ventral tubercles changing
from mammllate to transversely elongated early
in the ontogeny of the latter. The juvenile
Eodouvilleiceras differs from Ch. (Epicheloni·
ceras) leonhardtriedeli by the weaker ornament
of the latter and subrentangular whorl section.
OCCURRENCE. Socota Member. Upper
Aptian.
Family . EA YEITIDAE _ _ .
_ _
_
GenUs ·(Du n9if(Burckhardt MS) Ki·\
• . . ·-·· 1an and ebol. 1915 •.. ·--·----
Dufrenoyirz (Burckhardt MS) Kilian and Reboul,
1915, p.34.
TYPE SPECIES. Ammonites {urcatus J. de C.
Sowerby, by monotypy.
..[).yfre@yig pQt..emiJ:. sp.
Pl.1, fig. 6; Tex-figs. 5M:, 5 N.
Holotype. C-223x-10 . (U.N.C.M.H.N.C.P.Ht.
N.48).
The hdotype has thej>rotoconch preserved;
the conch is robust and has six volutions. To
approximately . an umbilical diameter of 5 mm
the flanks have broad convex bulges separated
by narrower depressions; the umbilical wall is
vertical but it rounds smoothly into the sides.
At about the above umbilical diameter a second
and fm er inflation devel6ps by longitudinal
splitting of uie liu-ger bulge just outside the umbilical
margin . At an umbilical diameter of 8
mm the newly appeared swelling (now a rib) de·
taches· from the primary (earlier) rib , and about
an umbilical diameter of 13 mm the secondary
rib occupies an intermediate location between
the primary ribs, at the same time it has began
to move outwards toward the middle of the
•
flank, but this displacement does not have aregular
starting point.
At . a height of whorl of 9 mm (D: 11
mm), corresponding to the adapical portion of
the last preserved whorl, the periventral clavi
are connected across the venter; at that stage
the ribs describe a wide adoral convexity to the
middle of the flank and from that point to the
ventral margin they describe a deep adoral
concavity; the ribs are straight or slightly
concave adorally on the umbilical wall. The ribs
tend to broaden from the adumbilical rim to
venter; the transverse profile of the ribs is rounded
with its adoral side long and oblique, the
adapical side is short and steep. On the shell the
intercostal spaces are slightly wider than the
ribs. The early portion of the last whorl is sub·
quadrate, truncated at venter, slightly wider
toward the adumbilical third of the flank;
approaching the aperture however, the whorl
section is slightly higher than wide. The siphon
is so close to venter that is creates a tenuous
raised line along mid·venter.
DIAGNOSIS. This species is characterized
by: A) its bold ornamentation, B) the change
in whorl section from subquadrate to subtrape·
zoidal; and C) the strongly falcoid ribs on the
flank, closely spaced on venter.
Meuuremanta. D Euw H W D/Euw D(H No.R.
% %
C·223x•10 44 26 19 16 67 43 3&
COMMENTS. Du{renoyirz scalata Casey
(1964, p. 386), is a similar species. Casey's.holo·
type (op. cit., pl. 66, fig. 1a, b) has intercostal
spaces narrower than those of the Colombian
species but the ribs are wider; on Casey's species
the ribs also do not have a slight adoral conca·
vity.
OCCURRENCE. Socotai Member. Upper
Aptian.
This species is named in honor of Profeasor
Gerardo Botero Arango, of the Universidad
Nacional, Medellin .
Du(renoyia codazziana..(Karsten)
Pl. 1, figs. 1, 7, 8.
1858 Ammonites CodiJzzianus Karsten, p.
108, pl. 3, figs. 4, 5.
1881 A T mmonites] Codazzianus, Karsten,
GaSb, p. 310.
1886 Ammonites Codazzianus, Karsten, pl. 3,
figs. 4, 5.
1913 Par. Tahoplites ]Codazzianus .Karat.,Kilian,
p. 344.
1925 Ammonites codiJzzianus Karsten, Burckhardt,
pl. 10; fig. 10·11.
? 1937 Colombiceras Codazzianus Karsten, Botero,
p.26, fig. 50,51.

zoNATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 59
194 7 Ammonites Codazzwnus Karsten,Spanish
version, p.375, pl. 3, figs. 4,5.
1964 D. f ufrenoyUI Jcodazzwna Karsten, Casey,
p. '397.
1964 Deshaye$ites codazzianus (Karsten),Eta­
yo-Sema, pars., p. 120.
c
1968 Du{renoyUI codazzwna (Karsten), Etayo· •
. ·· Sema, p. 28, fig.3.
1972 DufrenoyiD coddaziana (Karsten), Etayo·
Sema, p. 43.
UC::tocype. ·.· Kazsten's fi&1lred specimen under
·
·• •·
number 4 plate 3, 1858.
l>aratype. . Karsten's figured specimen under
- number 5, plate 3, 1858.
J:{ypocype; (U.N:c.M.H.N.C.P.N. 16,17).
'The. whorl section is higher than wide,
subelliptical; . the umbilical wall is subvertical, it
rounds smoothly into the gently convex sides;
the . maxjmum thickness of the whorl is at the
boundiuy between the central and the adumbi·
Uc!J} thirds of the flank, externally to this point
the sides a:re flattened and slightly convergent
on the adventral third of the flank. The ·1enter
is .relatively narrow, truncated. The umbilicus is
Shallow, .abot1t one half the width of the diame·
ter;
The ornament on the early portion of
the last whorl consists of fine, rounded and
untfonnlY wid ribs, slightly narrower than the
h1tereostal spaces. On the umbilical wall the
ribs ate weak and describe a shallow adoral
i:qticmty, then they trend prorsiradiate on the
.adumbWcal thiid of.the flank; at the boundary
.between the adumbilical and central thirds of
tlte flank they describe a crescentic adoral
;,Cpilvity. At e periventral margins all the
·J!bS'have slleht pyrifonn swellings, then the ribs
!JWIJig adorai!y describing a wide and prominent
arcrthe venter :n!mains narrow. At the bounda·
',ry b!ltween the adumbilical lind central thirds
qf 1:11 flank the ribs bifurcate, the point of
9l,!Utcation ing slightly inflated; commonly &
•·$9 th coIIP' n· ppears. without a connection to
, e Jacent pnmary nb •
. ;:\:?·:;··:; -··: .
:: ,· • .. On the internal old , all the ribs
-"! ; · ter then profile becomes rounded;
the ribs have an accenb.lated adoral arc on
venter throughout the ontogeny.
DIAGNOSIS. This species is differentiated
by: A) its fine, uniformly wide, sickle lile
ribs through ou t the ontogeny, B) the early
ontogenetic attenuation of the periventral nodes
and the broad adoral arc of the ribs on venter,
and C) the nearly constant suboval whorl
section.
Meuuzements. D Euw H W 0/Euw% D/Ho/o
La · Ye • 2 X3rt 14 111 11 40? 43?
COMMENTS. The small specimens are
(pl.l, fig.1,7) com r. arable to ''Ammonites
Codazzianus Karsten' (1858, p. 108;•pt 3, fig. 5
especially ) and to the photograph of the plaster
replica ot Karsten's original (op. cit., pl. 3),
given by Burckhardt (1925, pl. 10, fig. 10-11).
Karsten's figures (op. cit., pl.3, fig. 5a, 5b) are
restored and composite. [J. Helms , written
communication, 1976).
Du{renoyia formosa insculpta Casey
(1964, p. 396, pl. 66, fig. 9,9a) is a comparable
tonn but on the latter the ribs are only slightly
concave on the adventral third of the flank and
the primary ribs a:re crowded around the
umbilical rim. Casey (op. cit., p. 397) compared
his subspecies to D.codazzwna Karsten, poin·
ting out that the Colombian species has "denser
ribbing . .. and the venter has broader ribs and
sharper margins".
Dufrenoyia mulatoensis Humphrey (1949,
p. 127, pl. 9, figs. 11, 12) has less flexuous ribs
and they are barely adorally arcuate on venter.
Gerhardt's "Hoplites stuebeli" has distinct and
progressively separated ribs on flanks at a relati·
ve small size.
Duftenoyin wnctorum Biirgl, nom. trans.
PI. 1, flg. 2; Text-fig. 14.
1956 Dufrenoya texana sanctorum BUrgi, p.3,
p.6, p.12; pl .1, fig.2, fig.3; pl.3, fig.3,5.
? 19C4 D. [ufrenoyw] texana sanctorum BUrgi,
Casey, 1964, p. 386.
1964 Dufrenoya texana sanctorum BUrgi, Etayo-Serna,
p. 121.
1968 Dufrenoyw justinae (Hill), Etayo-Sema
p. 28, fig. 3, tab. 1.
1976 Dufrenoyia justinae (Hill), Etayo-Sema
et. al, tab. II, p.225.
Lectotype. Here designated. Specimen HB.406/1,
figured in Biirgl 1956, pl.l, fig. 2.
Type locality. Mesa de los Santos (Santander).
Hypotype. (U.N.C.M.H.N.C.P.Hy. N.18,19,20).
A) Up to 38mm D lC-223x-17]. The
whorl section is higher than Wide, slightly wider
toward the umbilical third of the flank; the
umbilical wall is subvertlcal and rounds abrup·
tly into the sides; the periventral margin is

60
subrounded The ornament consists of ncrrow
ribs which begin at the umbilical &.eL'll, they
describe an adoral concavity en the umbilical
wall, on the flank they describe 8ll l!doral are
on the internal half and a conei!Vity on the
external half; the rib& tennlnate in prominent
rounded, elongated clavi, the ribs are intercon·
nected across the venter.
On the internal mold the primary ribs
are represented by elongated awdlings corres·
ponding to flanges on the test, especially on the
adumbilical third of the fl&nk, the ribs contract
about middle of the flank md from that point
to the ventral margins they flatten in the fashion
of a propellor blade. The intercalary ribs appear
near the adumbilical third of the flank indepen·
dently from the prim8l'Y ribs. With growth the
ribs flatten on the adventral third of the flank
and tend to develop longitudinal grooves.
B) Up to 60mm [iC·223x-18]. After the
stage of accentuated flattening and grooving of
the ribs they abruptly loose their broad shape
on the external half of the flank and become
rounded, they also loose their periven tral clavi
and have a unifonn thickness, they then extend
onto venter in a wide adoral arc.
DIAGNOSIS. This species is characteri·
zed by: A) the early ribs with a propellor-blade
shape, and B) rounded adult ribs.
Meuurementa. D Euw H w D/Euw D/H No.R.
% %
C • 223x ·16 42 14 19 13 33 46 ?
C • 223x • 1 7 38 13 16 12 34 40 31
C • 223x · 18 68 23 22 17 39 38 14(1,12)
COMMENTS. This species differs from
Dutrenoyia hansbuergli n. sp., mostly in the
middle and late stages of growth. Casey (1964,
p.386) compared his Dutrenoyia notha to
D[ utrenoyia] texana sane to rum Biirgl after a
"topotype" (?) referred to Biirgl's figs. 3a·b,
plate 2; Casey concluded that the latter "closely
resembles the present species at small diame·
ters, but its venter is ribbed at &n earlier stage
and the umbilical wall is higher". My query as
to the topotype locality refers to the exact stra·
tigraphic horizon and not to the geographic
IU'ea.
Dufrenoyia sanctornm Biirgl
Pl. 1, fig. 3; Text-fig.14.
. (Morph I)
1956 Dufrenoya texana var. media Biirgl, p.3,
p13, pl.2, fig. 1, pl.3; fig. 1. :
1964 Putrenoya texana edfa Biirgl, Etayo .
Serna, p.121.
Reference specimen. The specimen Bff l/4
illustrated_ by Biirgl, 1956, pl.2, fi((.):
Reference locality. Mesa de Los Santos : c:-1· ••
tander).
..
F. ETAYO - SERNA
·
, ... , ·
A) Up to a diameter of 31 mm (C-223x-1;
La-Ye-1). The adapical section of the whorl is
higher than wide and it has a moderately wide
ventral region, the periventral margins are broa·
dly rounded, the flanks are moderately convex
to their central third, from this point to the
umbilical margin the sides are more tumid, they
round into U1e subvertical umbilical wall.
The earliest ribs observed (La-Ye-l;H:4
mm) are wide, strap-like; the primary ribs begin
at the umbilical seam and trend straight to the
umbilical rim, from where they are inclined
adorally across the adumbilical fourlh of the
flank, near this point a secondary rib detachs
·from the lldoral side of a primary rib; about
center of the flank the ribs describe a sharp
adoral arc, on the rest of the flank they describe
an adoral concavity and finally at the peri·
ventral margin they terminate and develop a
slight spherical bulge.
The width of the ribs is unifonn or
increases very little, and they are twice as wide
as the intercostal spaces. At a whorl height of 8
mm (La·Ye) the wide ribs cross the venter. The
ribs are more prominent on the adumbilical
fourth of the flank where they have acute to
broadly rounded tops, they have their maxi·
mum flattening on the adventral fourth of the
flank (particularly noticeable on the internal
mold). The periventral tubercles progressively
become more clavate; the adapical side of .e ·
ribs is steeper than the adoral side.
B) Up to 50 mm (La· Ye-2). The paddle·
like shape of the ribs become accentuated and
they tend to split longitudinally; the intercostal
spaces become very wide especially on venter.
At a D. of 54 mm (La-Ye-3) the ribs quickly
loose their paddle-like shape and become uni·
fonnly thin, strongly anteriorly arcuate on ven·
ter and the periventral clavi diminish in strength.
NOTE : This morph has coarser and flatter ribbing
tl1an the holotype.
Me8llllrements
D Euw H w DjEuw D/H No.R
% %
C·223x·1 31 9 14 11 29 46 36
C·223x•6 36 11 16 12 30
44
44 30?
C·223x·14 27 f 12 9 26 36
La·Ye·1 22 7 10 8 31 4!1 38
La·Ye-2 39 11 18 13 27 46 33 ·.
La·Ye·3 61 20 28 20 47 34
33
COM.i\1ENTS, This morph resembles to
Du{reno durangensis Humphrey (1949, pl27,
pl.9, figs. 3-4), but:at comparable diameters the
Mexian _speies h strong, outwardly directed.
"clavt", 1 ts nbs are;. more flexuous, rmer and se·
parated by wider intercostal spaces. Dufrenoyia
discoidalis Casey (1964, p; 393, pl.66, figs. HI;
text-fig. 140 g) resembles this mol'Jil., pecially
in its early ontogeny; the English species differs
by the latter development and attenuation of
its ornament, lack of an anterior arc of the ribs
on venter and no tendency for its ribs to be wi·
dely separated in the adults atage .

zoNATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 61
utmnoyia hansbuer«Jj
. 1, fig. 4; Text-fig. 14.
1956 Dufrenoya texana texana Burckhardt,
Burgi, p.3,6,12; [1.1 , fig.1; pl.2, fig. 2, 4;
. pl. 3, fig. 2, 4.
1964 Du{renoya texana texana Burckhardt,
Etayo-Sema, p. 121.
1965 Du{renoyia texana texana Burckhardt,
..,_.
. ·Biirgl; in Btirgl and Campbell.
i:IC}lotype. The specimen Bffl/1 figured by
.
Biirgl, 1956, pl.l, fig. 1.
Paratypes. The specimens figured by Btirgl 1956,
. . . . pl. l fig. 2 .. 4.
Hypo
.
type. (U,.N.C.M.rt.N.C.P.Hy.N. 23,24, 25),
Type locality:- Mesa de los Santos (Santander).
·>A) Up to 30mm D [C-223x-4]. The early
whorl section studied (Hw :4mm) is subellipti­
cal the. sides are slightly convex on the adum­
bi1ical third of the flank, the rema1nder is incli­
ned toward venter and rounds into a moderate­
ly wide venter. The umbilical wall is subvertical,
it rounds smoothly into the sides. The primary
ribs begin at the umbilical seam, they are prorsiritdlate
on the adumbilical third of the flank,
describe a sh allow adoral concavity on the cen·
tial and adventral thirds of the flank; on the inner.
half of the flank the ribs are narrow, acu te
but on the external half they are flattened. Externally
the intercostal spaces are as wide as the
ribs, and wider than the ribs on the in ternal mold.
The ribs end in small rounded tubercles which
connected across venter in a slightly arched
bar.
. ·. . B) Up to 50mm D (La-Ye-12]. The flexuous
earlY ribs tend to strrughten ana at the same
time the ad ventral third of the ribs changes from
Oa:ttened to rounded; the ribs are feebly arcu ate
· on venter and narrower than their intercostal
spaces: ·
.; C) Up to 125 mm D (C-223x-23]. The
whqrl section increases in he1ght and the ribs
accentuate their anterior arc on venter, on the
·nank the ribs resemble flexuous clubs.
.-·.· - -
. . ·
. . ·, ,DIAGNOSIS. This species is characterized
y: A} a prolonged stage during which the ribs
:·4?ross the yenter approximately normal to the
v,entr median line anQ. only late in the ontogeny
() they forl11 an adoral arc, B) the ribs show a
leaqendency to be sep arated into primary and
,} the change through ontogeny from . adventra·
U:ttercalary ribs after the early juvenile stage, and
· .

62
the specimen. In the Mexican specimens studied
by Humphrey and available to me, there is no
more than a slightly rounded widening of the
ribs approaching the periventral tubercles (UM
24248; UM 21854, Humphrey's pl. 7, fig. 5).
. Furthermore the ribbing is rather uniform
throughout the ontogeny, without bifurcating
ribs, as Humphrey (op. cit., p. 122) stressed
"Any suggestion of bifurcation is usually more
apparent than real, . . . ". On the basis of the
above features, I do not find any grounds
to use the specific names "texana" or ''justinae"
for the Colombian species.
Apparently unaware of Humphrey's paper
Burgi (1956) studied the so-called ''Du{renoya
texana Burckhardt" from Colombia. recognizing
three varieties. CantU-Chapa (1963, p. 57) also
referred the Colombian Du{renoyia ssp. to the
Texan species. Casey (1964 , p. 381) seems to
accept Burckhardt species without any comments
on Scott's and Humphrey's treatment
of Burckhardt's species. Recently Young (1972),
has shown that Hill's species is restricted to Te·
xas, (ib. p. 4): "the endemic species Du{renoyia
jusl,inae (Hql. 1893) I= D. texana (Burckhardt)
=ll. rqemen (Cragin)]".
Du{renoyia hansbuergli differs from D. sane·
toru m BUrgi because of the ad ventral flattening
of the ribs and the adoral arc of the ribs on the
venter from early in the ontogeny, however, they
are most early differentiated in middle and late
·
stages of growth.
Genus (jveodeshayesitelCasey ,1964
(non Prodeshayesites Casey, Dimitrova,
1967' p. 178).
}{e..odesba.yesites. Casey, .1964, p. 289.
TYPE SPECIES. Deshayesites stutzeri Riedel,
Original designation.
Neod sh pJ,. esites columbianus, .(!t!edel).
·· -·pJ -g · ; fig; 8; pt.· ·10; fig. 7; Text-figs. 6P,
6R, 6T; 15.
1938 Deshayesites colu mbianus Riedel,
p.401 pl.7 h figs. 16-20, pl. 12, fg.12,
pl.l4, Iig. ;;1.
1954 Deshayesites columbianus Riedel,
·
ImlaYjl) Rod and Mayne, p.266.
non 1954 Deshayesites colombianus Riedel,
Biirgl, p. 16.
1955 Colo mbiceras karsteni (Marcou),
BUrgi, 1955, p.15, pl. 4, fgs. 1,2.
1957 Deshayasites columbianus Riedel,
Btirgl, p. 134, pars.
1957 Colombiceras k-arsteni (marcou),
BUrgi, p. 136, pl. 9, fig.l.
F. ETAYO · SERN A
1964 [Neodeshayesites I colombian us I Rie·
del J, Casey, p.294.
1964 Co /ombiceras karsteni (Marcou), Eta·
yo-Sema, p.l19, pars .
1964 Hypacanthop/ites colombianus (Rie·
del}, Etayo.Serna, p.120 pars.
? 1965 Hypacan thoplites karsteni (Marcou ),
BUrgi in Campbell and Bi.irgl.
? 1965 Sonneratia colombiana Scott, nurgl,
in Campbell and Biirgl, 1965.
non 1968 Neodeshayesites cf. colombianus
[Riedel}, Etayo·Sema, table 1.
non 1972 Neodeshayesites cf. colombianus
(Riedel ), Etayo-Serna, p. 43.
Lectotype. Here designated, the specimen figured
by Riedel, 1938, pl. 7, fig. 16-17,
pl.12, fig. 12.
Hypotype. (U.N.C.M.H.N.C.P.Hy.N.26, 27, 28).
Type locality. Here designated. Apulo (Rafael
Reyes) anticline (see under com·
ments).
Up to 15 mm D (C-12C·19). The first
whorl of the phragmocone Is depressed ; the
second whorl is sligh tly higher th an wide, it has
flattened sides that round rather abruptly into a
.steep umbilical wall but merge evenly into a
broadly arched venter. On the adapical half of
the third whorl there are flat sinuous folds, se
parated by very narrow intercostal spaces, begi·
ning at the umbilical seam and becoming grea.
tly widened on venter, and strap-like and appea·
ring slightly arcuate; they are marked by "bun·
dies" of growth lines. On the adoral half of the
third whorl the "bundles" slightly elevate on
the umbilical . wall and ad umbilical third of the
flank and a true ribbing becomes established.
Up to 50 mm D (C-12-c). The whorl sec·
tion increases in height and the flanks slightly
converge to the arched venter; the whorl remains
thicker at the periumbilical margin. The
primary ribs begin at the umbilical seam: they
are concave on the umbilical wall, prorsiradiate
on the adumbilical third of the flank and con·
cave again on the central and adventral thirds,
crossing the venter straight and flattened like
bars. At the periumbilical region the ribs are rai·
sed in simple bullae (corresponding to pyriform
swellings on the internal mold), and have sligh·
tly flattened crests. The secondary ribs origin&·
te near the adumbilical fourth of the flank. In
general the ribs are high and prominent with
their adoral side a little higher than the adapical
one. The intercostal spaces are twice as wide as
the. ribs. The shell is thick.
C) Up to 75 mm D (C-12·C). The ribs ha
ve symmetrically slopit:tg sides and attain a uni·
form width and height ·except on venter where
they are slightly wider; on the living chamber
and approaching it the ribs tend to lose the

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 63
adoral concavity on the adven?"al ird of the
flank appearing nearly rectiradtate m this area.
'l'he condary ribs tend to .be .less frequent.
The maximum flaring of the nbs ts at the boun­
dary between the centrallmd adumbilical thirds
of the flank.
OJAGNOSIS. Riedel's statement(l93,
p. 40) seems to me accurate: "La nueva especte
esta caracterizada por sus pstill pronI}Ctdas
y dobladas, con intercalacton y btfurcacton trre·
guta!es".
.. POPULATION ANALYSIS. Sample C-12·
c-1 .. to • C·l2 • C-34, obtained from a sinl!le
"concretion" was selected as reference popula­
tion From. I!, two . specmes were identi[te as
morphologciilly "tdentlcal f:=closely stmilar]
to the specimens figured by R:tedel, thus I con·
sider th.em conspecific.
Specimen C-12-C-18 ==Riedel's pl.7, figs.
1617.
Specimen C-12-C-25 =Riedel's pl.7, fig.
18-20.
Using specimens of this sample a series of
correlation diagrams between mensurable cha·
racteristics were made and the position of the
two specimens considered as "identical" with
Riedel's .figured specimens were marked on the
diagrams. The types (see Text-fig.3B) of ribs are
rePresented by letters. 'The different combina­
ti.ons of ribs .distribution are as follows:
· · Type A : PqP, P2pP.
.
It: qP, P2pP, PP •
. c : ,P2pP, pp.
D: PqP, PP.
E: • P2pP.
·F : PqP ..
c:·
··· ··· · ; . . · •Fr.om
. . th. e diagrams (Text-fig.15) it is
.
.
·
:ev:tdent . . . that the type F is more frequent on
splmens of small diameter and types B and A
OJ1·.peciJnens of larger size. Type C seems to be
deyelC)ped . on the living chamber of larger
lti:lens; The lectotype as figured by Riedel
;eJ!ia to be PPqPP, but it could also be indica·
;!ibWg With pnrnary and sem1pnmary nbs
..

64
as flat bands slightly higher on their adoral border.
Near a diameter of 30 mm the ribs are
well defined, they widen towards venter, the
intercostal spaces are clearly defined on both
sides and venter; the adapical slope of the ribs
becomes shorter but steeper than the adoral
one and in general the ribs have very nanow
flat top. The ornament Is best described as
consisting of alternating primary and intercalary
ribs but several semiprimary or a sequence
of three primary ribs may also occur; the
secondary ribs detach from the primary ribs at
the umbilical rim but very soon this junction
moves outwards to the boundary between the
central and adumbilical thirds of the flank, but
on the internal mold they seem to begin near
the middle of the flank. The ribs are flared
midway on the flank and on the internal mold
small pyriform nodes appear on the umbilical
periphery.
B) Up to 50 mm D IC-219·6,101. The rib·
bing is stabilized as an aftemation ot primary
and intercalary ribs, they tend to have a uniform
width on the flank but they are slightly wider
and flatter on venter though maintaining a similar
elevation. At this stage the primary ribs decrease
their elevation from the middle of the
flank toward the venter whereas the secondary
ribs become higher. The whorl section is more
inflated toward the adumbilical half of the
flank and the umbilical slope becomes gentler.
C) Up to 70 mm D [C-219·1,5]. The umbilicus
has widened and its wall is moderately
inclined; the flanks are moderately inflated on
the adumbilical third. The ribs are rounded and
appear slightly arcuate on ven ter because of the
slight thickening periventrally and ventrally.
DIAGNOSIS. This species is characterized
by: A) the ontogenetic development of its oma- .
ment: early whorls with broad strap-like swe:
llings followed by an almost smooth tract after
which the ribbing begins with a division of a
primary rib, the junction soon disappearing
and the intercalary ribs appearing indeJ:endently
near the middle of the flank, B) the pro
gressively gentler gradient of the umbilical wall
through the ontogeny, C) the relatively inflated
whorl section and nanow venter, and D) its
relatively small adult size.
Measurements. D Euw H W D/Euw D(H N.R, T.r.
% %
C·219· 1 64 30 28 19 7 7 187 F?
C·219· 2 50 . 22 20 14 44 40 43 F
C-219· 3 62 20 20 12 38 38 43 A
C•219· 4 49 21 19 15 43 38 37 F
C-219· 6 49 20 19 15 40 38 60 A
C·219· 6 47 20 17 13 42 .36 47 F
C•219· 7 43 19 15 12 44 35 44 F
C·219· 8 387 18 16 11 477 397 38 D
C-219- 9 34 13 13 10 38 38 37 A
C·219·10 39 15 1f> 12 38 38 40 F
C-219·11 36 14 14 12 40 40 35 F
C-219·12 • 38 13 15?12? 7 ? 1 F?
C•219·13 23 8 8 7 36 36 26 :'/ E?
F. ETAYO - SERNA
Measurements. D Euw H W DfEuw D(H N.R. T.r.
OJ. %
C-219·14 26 9 11 9 36 42 24? E?
C·219·15 27 11 11 9 40 40 407 A?
COMMENTS. Neodeshayesites albertoalva·
rezi n. sp. differs from N. columbianus (Riedel)
because during its ontogenetic development,A)
the intercalary ribs develop independently from
the primary ribs earlier than in Riedel species,
B) the beveling of the umbilical wall occurs
earlier and more strongly in N. albertoalvarezi,
C) the ventral area is relatively narrower than
on Riedel's species, D) when the test is preser­
ved the conch appears more inflated and in
general the adults are smaller than in Riedel's
species, and E) the prominence of the ribbing
round the umbilicus decreases earlier in my
species.
From my study of these two _species it is
pertinent to add to the diagnosis of the genus
(see Casey, 1965, footnote p. 289) the following:
the early ontogeny prior to the stages
illustrated by Riedel (1938, pl. 7) shows first
folds that widen toward the venter, these folds
split longitudinally during following stage, and
finally the ribs individualize and their fold like
aspect on venter disappears. The ribs are never
interrupted on venter.
OCCURRENCE. Capotes Member. Lower
Albian.
This species is named in honor of geologist
Alberto Alvarez 0.
Ne odeshaesites k fsteni (M arcou\
Pl. 9, fig. ; pi.io, fig: ; text-figs. 6t, 6M,
6N, 17.
Lectotype.Th be designated,Etayo-Sema in prep.
Hypo types. (U.N.C.M.H.N.C.PHy .N.29, 30,. 31}
1858 Ammonites A costae, Karsten, p. 111,
pl. 5' fig. 1.
1875 Ammonites Karsteni, Marcou, p. 165.
1881 A [mmonitesJ acostae, Karst., Gabb,
p. 310.
1886 Ammonites KarsteniMarcou ,Karsten,
p. 62, pl. 5, fig. 1.
non 1928 Co lombiceras Karsteni Marcou, Basse,
p. 136, fig. 14, pl. 8, fig. 5.
? 1931 Colombiceras Karsteni Marcou, Rhein
in Hubach, p. 58.
1933 Colombiceras Karsteni Marcou, Spath,
p.654 ex Karsten 1886,non examples
in th e British Museum under Nos. C
4284a, b).
non 1936 Colombiceras Karsteni Marcou, Basse,
p. 88.

?
?
ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 65
1936 Du{renoya (?) nov. sp. Breistroffer,
.
p. 156.
1937 Colombiceras Karsteni Buell, Botero,
p. 26, figs. 48, 49.
19 38 Colo mbicerus Karsteni Marcou, Riedel
p. 35.
1938 Ammonites Karsteni Marcou, Riedel,
p. 42.
1947 Ammonites Acostae Karst., p. 378,
. pl.5, figs. on the left upper c:.omer;
Spanish vemion of Karsten's original
paper.
non 1950 Colombiceras karsteni (Mareou Basse,
p. 252.
non 1963 C. [olpmbiceras] Karsteni (Marcou),
Cantu Chapa, p.55.
·- 1964 Colombicerus karsteni (Marcou), Eta·
yo-Sema, p. 119, pro part.
1965 C.[olombiceras] Karsteni (Marcou),
· Casey, p.419, pro Karsten's original
material only,
: ·· . tip .to 10 mm D [C-5 01·28). At a whorl
bei!Ptt. of 3 mm, the internal mold is higher
than wide and it is divided into segments by
Wfde constrictions that are slightly arcuate on
,::nter; from that point on, flat bands are visible
·< ()n th:e ank, they appear as periventral swellings,
; C;_opmporane()usly on the shell the ribs begin
· · t(). . · ·
at the umbilical rim and are most
tile.
mm D [C-501-22,27,28). The
than wide, oval with section
-·Iat 18trutnc.ated on the maximum tltic·
third of the flank;
depression (contraction) of the
venter. particularly apparent
is preserved but not visible on
mold; the venter is flattened and
angular margins. The external urn­
is less thin half the diameter, the
is moderately inclined and rounds
Up to 60 mm D [C-501·17,18). The peri·
ventral rounded inflations of the ribs are accentuated
on the exterior but very little on the in·
temal mold. The secondary ribs loose their bi·
furcating nature and change to a more constant
alternating primary-intercalary Pq . The ribs
are moderately flattened on the adventral third
of the flank but continue very prominent near
the umbilical region; the umbilical wall becomes
steeper.
D) Up to 80mm D [C-501·1]. A clear al·
temation of primary and intercalary ribs Pq
dominates; the umbilicus is1wid8t;but the whorl
section has a proportionally ·lower height; the
ribs are prorsocline or weakly concave adorally
on the adumbilical third of the flank, they are
rectiradiate or feebly convex adorally on the
outer two thirds. The ribs are uniformly thick
on the side and venter; the periventral lnfla·
tions have almost disappeared. The ribs are prominent
on the umbilical wall as lf they arose
from the umbilical seam.
DIAGNOSIS. This species is characterized
by: A) the ontogenetic trend towards a wider
umbilical diameter versus a relatively short whorl
height, B) the persistent angular venter that be·
comes rounded late in the ontogeny, C) the
coarseness of its ribbing, and D) the relatively
shallow intercostal spaces.
Meuurementa D Euw H W DjEuw Dftl N.R. T.t.
% %
c-501· 1 75 36 25 20 46 32 43 F
c-501· 2 49 24 20 16 47 39 40 F
C-501· 3 60 25 23 17 43 39 38 F'
C·501· 4 641 32 23 18 49 37 42 A
C-501· 5 159 27 20 17 44 36 38 A
c-501· 6 53 23 20 liS 42 37 42 F
C·l501· 7 53 26 20 12 415 36 38 F
C-501- 8 47 21 18 13 43 38 39 D
C·501· 9 38 17 15 12 43 38 38 F
c-501·1 0 39 16 16 11 42 37 40 A
C·501·12 42 18 15 12 40 34 40 F'
C·501·13 17 11 10 8 51 ISO +301 F'1
C·501•14
C-501·1 6
C'·IS01·16
C-501·1 7
C-601·18
C·501·19
C·501·20
C-601·21
C·501-22
C·501·23
C-501·24
C·501·25
C-1501·26
C-601·27
C-501·28
C·501·29
C-601-30
C-501·31
C-501·32
C·601·33
C-601•34
c-501·35
C·501·38
C-501-37
59 25 22 18 41 36 41
51 23 21 115 44 38 37 A
54 24 20 13 44 36 37 F
62 23 20 14 42 37 34 E
55 25 21 14 415 37 34 A
43 18 17 11 43 38 37 F
45 19 18 14 43 41 32 F7
41 19 16 13 46 38 32 D
41 17 16 11 40 36 31 A
39 17 14 11 42 35 31 E
41 19 17 7 46 40 317 F
37 15 14 9 40 37 31 E
32 liS 12 9 42 33 32 D
31 14 12 8 45 38 33 F'
29 13 11 8 45 38 32 F
29 12 12 9 41 41 34 F
19 8 7 7 42 36 327 F
151 21 21 17 40 40 35 A
49 22 18 14 44 36 42 F
46 20 17 14 42 36 41 A
44 19 18 11 43 36 39 D
37 15 14 11 40 37 42 F
36 15 14 9? 40 39 36 F
34 13 14 10 38 41 39 F

66 F. ETA YO · SERNA
Meuu:rement.B D Euw H W DfEuw D/H N.R; T.r.
% 04
C-601·38 23 9 9 7 39 39 39 F
C-1101·39 311 14 14 10 40 40 37 F
C·II01-'0 40 16 lli ll 38 36 43 F
C•601-'1 34 14 13 10 40 37 41 F
C·IIOl--'2 30 12 12 9 39 39 37 F
NOTE: F' signifies that there are two interca·
lary ribs between two primary ribs.
COMMENTS. "Ammonites Karsteni Mar·
cou" [1875, p. 1651 (ex Ammonites Acosroe,
Karsten, 1858, p.lli, pl.5, fig.1), was collected
acco"Ung to Karsten in "Tocaima", a locality
where no Cretaceous rocks crop out. Consequently,
if Karsten's sample does not represent
float, it must come from the only area where
Middle Cretaceous beds are present, that is
between Apulo (Rafael Reyes) and Anapoima,
where sample C-219 was collected.
Karsten's original description is as follows:
"Testa discoidea, complanata, dono subrotundo
late umbilicata, argute costata; costis dorsum
clngentibus alternantibus brevioribus aliis completis
undulatis, aliis interjectis in latere evanes·
centibtis vel hie· illis sejunctis; anfractus exteriores,
interiores ad medium tegentes; a p, ertura
· ovata rotundata; septis l"teraliter trilobis '.
"Durchmesser . .......... 48 Millimeter
Hohe der letzten Windung 16.5 "
Dicke der letzten Windung 12
"
Weite des Nabels . . . . . . 14 "
However, this description and measurements
do not correspond to the figure of the
specimen given by Karsten (ibid. pl. 5, fig. 1a,
1b ). The diameter of the conch corresponds
well on fig.1a, based on the intercostal distance
likewise the height of the last whorl is als
correct. The width of the umbilicus if measured
parallel to the diameter, and touching opposite
points of the umbilical seam (fig.la.) is 18 mm
on the figure contrary to 14 mm as stated by
Karsten, consequently the conch was drawn
more evolute and rounded than it is in reality
(did the artist try to indicate an oblique umbilical
wall?). On Kmten's figure 1b, there is an
error in the perspective: the view was not drawn
looking straight at the specimen but is an oblique
view, consequently the "aperture" looks
higher, and if my interpretation is correct the
artist tried to draw. the aperture following the
path of a primary rib, consequently the width
(thickness) of the aperture is greater in the
figure than on the original (=18 mm va.14 mm).
The young of Neodeshayesites karsteni
(Marcou) resemble the specimen fi red by
lliedel (1937, pl. 7, figs.12-13) as a ' transitio­
nal spec1men" between "Deshayesites stutzeri ..
and ·neshayesites nodosus " the adults of the
latter species have very fine or flattened ribbing
and the whorl section appears higher than In N.
karsten. rom N .. colum . bilzn !' s (Riedel) N:
karstem dtffers by 1ts hemer nbbing, rounded
throughout on the sides. On Riedel's species the
ribs are high, acute and only adventrally roun·
ded, furthennore on his species . the umbilical
wall is persistenly steeper.
OCCURRENCE. Lower Albian.
Neodeshayesites karsteni (Marcou)
Pl.lO, fig. 9; Text-fig.17.
(Morph I)
Hypotype. C-501-2 (U. N. C. M. H. N. C. P. Hy.
N.32).
This morph is characterized by its rounded
venter very early in the ontogeny; its ribbing
is attenuated, not flanging at umbilical
rim; on the flanks of the internal mold the ribs
appear as concentric arcs.
OCCURRENCE. Lower Albian.
deshaye6.ituneylatum,.n. sp.
Pl .lO, ffg . 8, 10; Text-figs. 7 A, 7G, 7H.
Holotype. C-501·0 (U .N .C.M.H.N .C.P .Ht. N .50).
The whorl section is higher than wide,
ogival, with broad venter and flattened flanks;
the umbilical wall is beveled and rounds
smoothly into the sides. The ribs are wide and
low, on both test and internal mold, they are
separated by shallow intercostal spaces that are
subequal to the ribs on the adapical portion of
the last whorl but appear as a narrow furrow on
the adoral half; the ribs arise in pairs, rarely in
threes, from stressed periumbilical bullae, they
are slightly sinuous and have delicate rounded
periventral thickenings. At a diameter of 55
mm the periumbilical bullae disappear and the
ribs are straplike. Although the ribs are wider
on venter they increase their width slowly.
DIAGNOSIS. This species is characterized
by the change in its ornament from ribs that
arise from accentuated periumbilical bullae
to non bullate girdle like ribs, and by its flatte·
ned ogival section.
Meuu:rementa D Euw H W D(Euw•fo D/H%
C•II01o0 66 28 27 19 43 41
COMMENTS. This species resembles Neodeshayesites
ro tundus (Riedel) (1938, p. 39,
lam. 7, figs. 14,15; pl.14, fig.20) but the latter
has finer ribbing, more numerous and fmer periumbilical
bullae; and the venter is narrower.
Neodeshayesites.contracta (Riedel)_
PL9, fig. 7; Text-figs. 7B, 7D, 7E, 7F.
1938 Deshayesites stutzerivar. contracta Riedel •
p.38, pl. 7' fig. 8, 9; pl.14, fig.18.
Hoiotype. Riedel's fii!Ufed specimen.
Hypotype. C-500 (U.N.CM.H.N.c.P.Ht. N.33,34,35).
A) Up to 20 mm D (C-500-1). The whorl
section is higher than wide, the tlanks are sligh·
tly inflated, with their adventral thitdconwrgmg

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 67
t6ward the venter; the umbilical wall is vertical.
Tlie inner part of the conch observed (H: 4 mm)
haS a .. truncated venter and .subangular ventr
margins. The primary ribs anse from the umba­
lical rim where they usuill!Y have a bulla, .ey
describe an adoral concavaty on the umbalical
wall an-d extend pri>rsiradiately to the boundux
betwen the central and the adumbilical thirds
of the flank; at this point the ribs bifurcate; and
on ·· the adventral half each branch describes a
wide adoral concavity and finy cross venr
with ·a weak adoral arc. At thiS stage the nbs
appear like sickles with long handles. The ribs
steep adapical side, they are slightly wider than
are broad; rounded to flat topped and have a
th intercostal spaces. On this specimen there
iJlay be seve!al non bullate ribs or one .rib wth
8: less ptormnent bulla between two nbs wtth
prominent bullae.
umbilical bifurcations become regularized;
· B)Up to 100 mm D (C-500-2). The peri­
s:ollle intercalary ribs may approach a primary
rib near the umbilical rim as bifurcating from it
but the real branching occurs at the boundary
between the adumbilical and central thirds of
the flank; at this point the ribs tend to develop
a·t;a'iangular swelling. The venter is progressively
very inclined; the conch has periodical constric·
more rounded and the umbilical wall becomes
f.ions on the living chamber. The living chamber
is aproximately half the length of the whorl.
The ribs are rounded on the umbilical third of
the flank, .but they are flat, terrace like on the
cimtraland adventral thirds.
The. general trend of the ribs is to descri­
. tie a wide. adoral arc on most of the flank with
deUcate concavities both on the adumbilical
d adventral fourths. Likewise the secondary
rib. may join different primary ribs on each
flk.
< · DIAGNOSIS. This species is characterized
ro\}gh its ontogenetic development by: A) its
!ascic!Jlllte ribbing and increased crowding of
·the nbs around the umbilical margin, B) the
liJPid Increase in whorl height, C) the narrow
Venter, and D) the numerous fine ribs.
· ·· ··
'M'aiunmenq D Euw H w DJEuw D/H No.R.
i'QO •l
•. c"5oo : 2
cdo3
9·00.
: l;h500 . 5
'.;,cioo -6
' c-
·.>_ .. :· :· "':
20 6 9
4o 115? 17
63 22? 21
67 25 26
71 29 27
+77 29 31
7
?
15
17
17
20
%
33
37
41
37
40
38
%
46
42
39
38
38
40
40?
52
27(lf2)
61)
70
?
< . ·
COMMENTS. Although "Deshayesites stut­
nvar. !Zont:czcta Riedel" was based on a juvetil.I
thank .t ·is a valid species. The specimen
·.·f'l,UD!mow:n l.ocaljty has a more consistent bi·
·;,.red by Burg] (1957, pl. 8, fig. 3a, 3b) from
., ating nbbmg pattern. The present morph
o:;mbles some species of Burckhardites, for
: . rmple
B. palumbes Humphrey (1949, p.15,
>l1 . 12, figs. 1,2), but the latter has a greater an-
''- . : _· n-e.· _ .· . ·· . · . I!Se. do f the whorl heig t. and the ribbing is not
< sse around th umbthcus.
Genus [§toyiggwicer ?,.::;
TYPE SPECIES. Ammonites Treffryanus Karsten,
1858, p.150, pl.4, figs.
1a, lb.
DIAGNOSIS. High whorled, involute
conchs ornamented from early iri the ontogeny
with biconcave primary ribs and flexuous intercalary
ribs, the former may be raised around the
umbilical margin but no tubercles are present.
When the shell is preserved all ribs have rounded
tops and sides, on the venter they tend to broaden
in a visor-like manner but they cross normal
to the median ventral line or with a weak adoral
arch. The whorl section is high, ogival, with wi·
de venter and inclined umbilical wall. The bor·
der of aperture is plain with a shallow sinus at
the umbilical margin.
-
Suture line with E/L large, L symmetrically
trifid, L/U and U2 high.
COMMENTS. Stoyanowiceras differs from
early whorls and straight ribs, wedge shaped
with steep sides, of the latter genus.
Stoyanowiceras tref£B:anus (Karsten)
PI.5, fig.3; pl.4, fi{7Text-Mgs.7M,7N,7Q
1858 Am. rmonitesl Treffryanus Karsten,
p. 101J, pl. 4, ffg. 1.
1862 Ammonites Treffryanus Karst.,Gabb,
Colombiceras Spath (1931) by the coronate
p. 75.
1875 Amm. [onitesl Tre{fryanus Karsten,
Marcou, p. 164.
1883 Hoplites Treffryanus Karst, Uhlig,
p. 158.
non 1883 Hoplites Treffryanus Karst, Uhlig, p.
251, pl. 21, fig. 2.
1886 Ammonites Treffryanus Karst., Kars·
ten, p. 62, pl. 4, fig. 1.
'! 1898 Hoplites Treffryanus Karst., Gerhardt.
p. 158.
1899 Parahoplites Treffryanus Karsten,
Anthula, p. 110. ·
non 1899 Parahoplites Treffryanus Karsten,
Anthula, p. 115, pl. 8, fig. 6.
1907 Am. [ monites l Tre{fryanus Karsten,
Sinzow, p. 485.
1907 P. [arahoplites] Treffryanus Karsten,
Jacob, p. 77, non p. 81.
1913 Par. [ahoplites] Treffryanus Karsten,
Kilian, p. 344.
1921 Am. [monites] treffryanus Karsten,
Spath, footnote p. 317.

68
?
?
?
1922 Parahoplites Treffryanus Karst., Collet
in Eugster, p. 254.
1931. Am. [monites J Treffryanus, Karsten,
Spath, p. 654. .
l
1936 Deshayesites (?) Treffryanus Krst.,
Breistroffer, p. 155.
1937 Am. [monitesJ Treffryanus Karsten,
Scott, p. 37.
1938 Calombicerus tref fry anus Karsten,
Riedel, p. 50.
1945 Parahoplites (Parahoplitoides) treffry
·
(Karsten), Royo y Gomez.
1947 Am [monites J Tre{fryanU8 Karst.,
Karsten, SpaniSh version, p.376, pl.4,
top. figures.
1949 Ammonites Treffryanus Karsten,
Humphrey, p. 151.
1949 Ammonites Treffryanus Karsten,
Stoyanow, p. 121.
1952 C. [olombiceras] treffryanus Karsten,
Basse, p. 655.
1963 Colombiceras tre{fryanus (Karsten),
Cant:U·Chapa, p. 55.
1964 Colombiceras Treffryanus (Karsten),
·
Etayo-Sema, p. 120, pars.
? 1964 Burckhardites Tref fr yanus (Karsten),
Biirgl, in Campbell and Biirgl.
Holotype. The specimen illustrated by Karsten,
1858, p. 109, pl. 4, fig. 1. Lost during
2nd world war (J. Helms, written
comm. 1976).
Neotype. Here designated Plate 4, fig.l.
Paratype. (U.N.C.M.H.N.C.P.Pt. N. 52, 53).
A) Up to 5 mm D. The whorl section is
transvrsely subrectangular, with angles rounded;
-'ong the umbilical rim there are broad
undulations that soon become ridges separated
by wide constrictions especially prominent on
the flanks; the ridges have a weak longitudinal
groove, on the shell these ridges are represented
by flexuous dfvided bands .
. B) Up to 21 mm D (Pens. 1, 2, 3, 4). At
a diameter of 14mm the whorl section(Pen.N.2)
is subrectangular, the flanks are flattened, the
venter and periventral margins are rounded, the
umbilical wall is subvertical near the umbilical
seam but externally is more inclined, and rounds
smoothly into"the side.
The ornament consists of rounded
flexuous primary ribs that begin on middle of
the umbilical wall, curve adorally in the lower
part of the whorl, curve adapically on the
middle part, curve slightly adapically on the
upper part and then cross venter straight.
F. ETA YO · SERNA
On the periven tral third of the flank and
on venter the ribs are moderately broad, club
shaped; the secondary ribs, usually one but
occasionally two, intercalate between the
primary ribs; the secondary ribs taper toward
the periumbilical third of the flank where they
fade out; sporadically one of the secondary ribs
slants toward the following primary giving the
impression of bifurcating from it, likewise an
actual bifurcation from the adoral side of a
primary rib may also occur. In general the
primary ribs are more prominent than the
secondary ribs. The intercostal spaces are twice
as wide as the ribs. When the shell is preserved
the tops of the ribs are broadly rounded and on
venter they attentuate.
C).tJp to 45mm D (Pen 10). With growth
the ribs gain an elegant biconcave outline on the
whorl sides; the primary ribs become broadly
rounded almost flattened on the adventral half
of the flank. Adoral arching of the ribs on ven·
ter does not occur. Some of the intercalary ribs
fork from the adoral slope of the preceding primary
rib on the adumbilical third of the whorl.
Sporadically some primary ribs are more promi·
nent. The whorl section increases its height but
not its width, consequently it is always compres·
sed. The involution line is near the boundary
between the adumbilical and central thirds of
the flank.
DIAGNOSIS. As for the genus.
MEASUREMENTS. The specimens stu·
died do not allow accurate measurements.
COMMENTS. The following is Karsten's
original description (1858, p. 109): "A. testa
compressa umbilicata, dorso rotundata, transversim
costata; costis rotundatis, flexuosis,
inaequalibus, dorsum cingentibus; altemantibus
incompletis, una suturam unbilicalem attingente
alia solitaria vel rarius gemina in latere evanes·
cente, Iibera vel rarius costae anteriori (majori)
conjuncta; anfractibus subinvolutis, exteriore
tres partes interioris involvente; apertura com·
pressa ovato-elliptica: umbilicoparvo; septis lateraliter
trilobis profounde partitis, margine
crenato-sectis.
Durchmesser 180 Millimeter
Hohe der letzten Windung 53
"
Dicke derselben 50
"
Durchmesser des N abels 20
"
Karsten's species has been the object of
many comments in paleontological literature:
Uhligh (1883) referred this species to lloplites;
Anthula referred the species to his group of Parahoplites
melchioris, but Sinzow (1907) cha·
llenged the interpretacion "weil wir die Gattung
gar nfcht kennen, zu welcher Am Treff ry anus
Karsten gerechnet wird".
Spath (1921, p.137) considered A. Treffryanus
Karsten in the same group as A. crassicostatus
d'Orbigny·oecause they " ... show
the peculiar flattening of the costation . • • ";
when proposing- his genus Colombiceras (1923,

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 69
p 64) Spath did not mention Karsten's species
bt Jater (131, p.654) whn comptnti f!g on an
'Indian specieS of Colomb1ceras be: considered it
very close to Karsten's species, Riedel (1938, p.
50) referred Karsten's species to Co lombiceras.
Stoyanow (1949, ·p; 121) challenged Spath and
Riedel " • . . tendency . . . to connect with
Colombiceras flat-ribbed species for which the
presence of tuberculate ribs has not been
proved, as Ammonites tre{{ryanus Karsten
(1856, p. 109, pl. 4, fig. 1a, 1b) . . • ", and he
furthermore indicated that in following Spath
and Riedel's ideas there should be a group
for Karsten's species. Casey (1965, p. 420) has
followed Spath's treatment of Co lombiceras,
however, his suggestion of a transient coronate
stage is not confirmed by disection; the deve·
Iopmerit of the ribbing in Stoyawiceras is like
that of Neodeshayesites.
Karsten wrote that his species came from
"Tocayma" (sic, p.109), but as previously com·
men ted no Cretaceous rocks crop put in the im·
mediate neighborhood of this locality, and be·
cause no other nearby region than the area co·
vered in the present report (Apulo . La Mesa),
has exposed Lower Cretaceous rocks, this is se·
lected as type locality for Karsten' species. The
specimens studied in this report closely resemble
"A mmonites Treffryanus Karsten", none of
of them, however, is as large as the holotype.
"Sonneratia colombiana Scott" the holo·
type (T.C. U. 1108) of which I have examined is
here considered a member of Stoyanowiceras,
contrary to Casey's views (1954, p.llO; 1965,
p. 400, p.516), and its specific status is retained
here because of its more distinct ribbing and regular
alternation of primary and secondary ribs,
the ribs are sharper on the inner half of the
flank. and narrower on the external half of the
whorl than in K1li'Sten's species as it is treated
in this study.
OCCURRENCE.Upper Aptian.
_.: . . Stoyanowiceras tre{{ryanus (Karsten)
·
"PI: a; ng.s. · · - · · · · ·
(Morph I)
Paratype. (U.N.C.M.H.N.C.P. Pt. N.54).
Th morph is peculiar because its orna·
ment. is stressed very early in the ontogeny,
espe1ally the flanging of. the ribs on the umbili·
·
cal nm.
Me&.u:rementa o
Penldlv. 14 18
Pen.Uv: 13 30
Euw H W
7 7 8
10 12 12
OCCURRENCE. Upper Aptian.
D/Euw% D/H "'o
39 39
33 40
Stoyanowiceras treffryanus (KaJSten)
P1.3, fig.12.
(Morph II)
Paratype. (U.N.C.M.H.N.C.P. Pt. N.55).
A single specimen is available. The whorl
.sectl(ln is higher than F and has a broadly
rounded venter, the sides ate slightly compres­
sed on the adventral third of the flank the cen·
tral and adumbilical thirds are slightly convex;
the umbilical wall is inclined and merges smoo·
thly into sides.
The ornament consists of distinct ribs
which begin at middle of the umbilical wall; on
the early portion of the last whorl the ribs
bifurcate at the margin of the umbilical wall,
they are fine, rounded and slightly biconcave a
bit projected forilard on venter; this type f
ornamentation persists until the beginning of
the adoral third of the last whorl where the
ribs become strongly biconcave, and strongly
arcuate on venter; bifurcation of the ribs may
occur on one side but not on the opposite. The
intercostal spaces are one and a half times as
wide as the ribs.
NOTE : This morph is chuacterized by: A) the
rapid change in flexuosity of the ribs
that accentuates with growth, and B)
the narrow well rounded ribs,
Measurements 0 Euw H W D{Euw% DtH% N.R.
PeDSUv. 7 36 11 16 13 31 43 37
Sto.;xt;WJ!JJ(ctras
cin tatuf1l.n. sp.
PJ.7; fig.9.
,._.,,. .. , " -· . . • . . ,. . . • ., .. ,-- ·-,.4o,oo•,-•--,.
Holotype. T.I.P. Guaduaus (U.N.C.M.H.N.C.P.
Ht. N.51).
Only one specimen is available. At the
beginning of the last preserved whorl the sec·
tion is higher than wide, the venter is rounded
and the whorl sides are slightly convex; the
umbilical wall is oblique; toward the adoral end
of the conch the height of the whorl increases
in relation to the width,
The ornament consists of ribs which
begin at the umbilical seam where they describe
an adoral concavity and extend up to a little
beyond the umbilical rim, then they describe an
adoral arc on the adumbilical half of the whorl;
up to this point the ribs are raised and prominent,
from here up to the periventral margin
the ribs are slightly concave adorally, they be·
come wide, broadly rounded to flattened and
go straight across the venter.
There is a regular alternation of primary
and intercalary ribs on both flanks, the intercalary
ribs begin near the umbilical third of the
whorl where they slant adapically and approach
the preceding primary as if forking from it and
in some instances it seems a true bifurcation.
The intercostal spaces are narrower than the
ribs.
DIAGNOSIS. This species is characterized
by its low and broad heavy ribs.
Measurements D Euw H W D{Euw% DtH%
T.I.P.Guaduaa 79 24 36 26 30 46

70
COMMENTS. This species is closely simi•.
lar to Stoyanowiceras tre{fryanus (Karsten),
but has lower and broader ribs than the latter.
Stoyanowiceras colombiana (Scott) has sharper
and higher ribbing than S. cinta tum , n.sp.
Parahoplites nicholsoni Benavides-Caceres
also resembles S. cintatum n. sp. but the Peruvian
species has a wider umbilicus, its umbilical wall
is vertical and the ribs regularly bifurcate, but
the opposite is true in the Colombian species.
F. ETAYO ·SERNA
OCCURRENCE. Upper Aptian.
I'Ri: . • ) r. f.,, ;,.o,r .. ,,
.
oJ!IIIil :t?SrcdiiSiii .,.!' · · · · ··· fJv ru.:.'' )_.(d):." 'i
TYPE SPECIES. Riedelites esthersemae n. sp.
Genus , .f'fdelltes n.g. "' (£:r·a,, :

zoNATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 71
DIAGNOSIS. This species is characterized
by: A) the increase in height of the whorl sec­
tion B) the irregular accentuation of the rib
flexusity during the juvenile stage, and C) the
tendency of the ribs tow:ard flattening on the
adventral third of the whorl side during the
adult stage, giving the ribs a rursiradiate aspec.
Meumementa D Euw H W D/Euw
%
C • 200B 23 9 9 19 39
C • 200A 36 13 13 11 36
D/H No.R.
%
39 ' 38
36 29(3/4)
COMMENTS. At first glance these speci·
mens appear similar to the specimen described
by
·
·
·
Basse (1928, p. 136, fig. 14; pl. 8, fig. 5) from
Villa de Leiva and identified as Colombicera.s
ka,:steni (Marcou), which later was included
within the genusPegnaceras (as Penaceras}Cantti­
Chapa, 1963, p. 55), however, I feel the latter
genus should be restricted to the Mexican spe­
cies·in the type species of Pegnaceras:the distan·
ce b'etween the ribs does not increase with growth ,
thefhlckening of the ribs is "transversely elon­
gate" (Humphrey, 1949, p. 142), and the early
development of the sculpture unknown, conse·
qtiently I consider the rursiradiate adult ribs an
undiagnostic character; it is also present on
"Acdnthoplites ? adkinsi'' and "Acanthoplites ?
sandidgei" described by Humphrey from Mexico
but no assigned to Penacera.s by CantU-Chapa.
1\ll&Se's illustrated specimen is poorly preserved
and does not warrant an extensive discussion.
· .· OCCURRENCE. Socota Member. Upper
A,ptian.
'-·-· iefe M tes obliquum £Riedel)
•.··.· · .•. • L \l.g. 3; Pl. 6, fig. 7; Text-fig. 7P.
' .
·
(Mozph I).
. 1938 Parahoplites obliquus Riedel, p.33, pl.6,
figs. 11-13, pl. 12, fig. 9, pl. 14, fig.14.
1957Parahoplites obliquus Riedel, Btirgl, p.135
1964 Parahoplites obliquus Riedel, Etayo-Ser-
· . na, pars, p. 118.
1965 Colombiceras obliquum (Riedel), Casey,
.. · . p; 420.
)968 Colombiceras obliquum (Riedel), Etayo·
· .
. ·.· . Bema, p. 34, fig. 7, tab. I.
.
197.0 Colombiceras obliquum (Riedel), Wied·
, mann, p. 4 84, ex rev. of Etayo-Serna's pa·
per.
,1972 Colombicei'as obliquum (Riedel), Etayo·
' Serna, p. 45.
1976 Clombiceras obliquum (Riedel), Etayo·
' ' Serna et al, p. 225, tab. II.
.
Lectotype. Here designated the specimen illus·
trated by Riedel, 1938, pl. 6, fig.
11-12.
Hypotype . (U.N.C.M.H.N.C.P.Hy.N. 38, 39,40)
Type Locality. Utica (Cundinamarca).
A) Up to 20mm D(C-199-B,C). The earliest
part of the last whorl is slightly wider than
high; the sides are slightly convex, they round
smoothly into the arched venter and the subver·
tical umbilical wall.
Ribs begin on outer half of umbilical wall,
trend slightly prorsiradiate on ·the adumbilical
third of the flank and then trend radially to the
ventral margin. The ribs have a rather uniform
thickness to the adventral third of the flank
where they broaden and cross the venter with a
delicate adoral arc; the ribs are well defined and
separated by intercostal spaces about one and a
half times as wide as the ribs.
Sporadically a secondary rib branches
from the adoral slope of a primary rib near the
umbilical rim. An alternation of intercalary and
primary ribs become dominant on the internal
whorls, some of the primary ribs become stron·
ger. The ribs become progressively wider apart
with growth.
B) Up to 40 mm D (C-200·0). At about
a diameter of 20 mm the ribs have a regular pattern
of alternating uniformly raised primary in·
tercalary ribs, the latter sometimes inclined to·
ward the preceding primary rib as if bifurcating
from it at about the adumbilical third of
the flank. On the adoral fourth of the last
whorl the ribs are rm e, delicately falciform.
C) Up to 50 mm D (C-514-B). The whorl
section is subquadrate with flattened venter and
rounded periventral margins; the umbilical wall
is subvettical and rounds smoothly into the sides.
The ornament consists of strong ribs as in
the previously described specimens; the primary
ribs begin at the umbilical seam, describe an
11.doral concavity on the umbilical wall and the
adumbilical third of the flank, on the middle
third the ribs describe a weak adoral convexity ,
on the adventral third they describe an adoral
concavity then go straight across the venter.
At this stage the ribs are acute on the
flanks and broadly flattened to rounded on the
venter but are slightly more flattened on the
adapical part of the last whorl than on the adoral
part.
COMMENTS. This mozph is characterized
by: A) its early whorls with weakly sinuous
ribs, slightly wider on venter, some of them
sporadically emphasized or bifurcating near the
umbilical rim, B) at lntennediate stages of
growth the ribs are progressively more distant
from one to another with primary and interca·
lary ribs alternating, and C) throughout the onto·
geny the ribs preserve their delicate flexuous
oblique trend.

72
Measurements D Euw H w DfEuw D{H N.R.
"1. %
C·199·B 22 10 8 8 45 36 44
C·199·A 20? 87 8? 8? 40? 40? 22(1/2)
C·514·B 60 22 16 1 44 32 18(1/2)
COMMENTS. The specimens illustrated
by Riedel represent juveniles to young adults
(1938, p.33,34; pl.6, figs. 11-13; pl.12, fig.9;
pl.14, fig. 14) agreeing fairly well with the early
whorls of the specimens here studied, on them
the ribs are not yet broadened on the venter,
but distant spacing of the ribs after the crow·
ded stage is visible. This species differs from
Riedelites quebradanegra by its more flexuous
and projected ribs and because its whod section
is not compressed.
OCCURRENCE. Lower San Gil Formation
(Segment B). Upper Aptian.
Riedelites [,ilosum». sp.
Pl.7, fig.1; Text-fig. 7U.
Holotype. C-225·6 (U. N. C.M.H.N.C.P.Ht.N.53)
Paratype. (U. N. C. M. H. N. C. P.Pt. N.57,58)
Only internal molds are preserved. A) Up
to H:13 mm (C-225,7,8). The whorl section is
subrectangular, approximately as wide as high,
it has rounded periventral margins, broaly ar·
ched venter and short, approximately 45 incli·
ned umbilical wall.
The ornament consislb of fine rounded
ribs with some beginning at the umbilical seam;
these describe a slight adoral concavity on .the
umbilical wall, then trend prorsiradiate descri·
bing a weak adoral convexity near the middle
of the flank and an adoral concavity, more or
less accentuated, on the adventral third, then
they arc adorally on venter; the adapical side of
the ribs is steeper than the adoral side; the ribs
have a rounded top.
The intercostal spaces are three times as
wide as the ribs on venter, they narrow on the:
umbilical margin to one and a half times as wide;
Up to H:20 mm (C-225·6). In this speci- .
men the whorl section is depressed, wider than
high; there is a continuous curvature from one
flank to the other; the umbilical wall is very re·
duced. The ribs are very prominent, they cross
the flanks, varying from weakly flexuous to al· .
most straight; they are slightly wider on venter .
and rounded; one or two of these ribs become
emphasized and bifurcate . near the middle of ·
the flank; no tuberculization is present; the in- ,
tercostal spaces are twice as wide as the ribs and .
channel like on venter.
DIAGOSIS. This species is characterized
in the adult stage by: A) Its wide subrectangular
whorl section and B) its annular ribs and
deep intercostal spaces.
F. ETA YO - SERNA
Mea.surements D H w
C·225·o ? 13 12
C•225·6 ? 20 23
C·226·7 ? 13 13
C·225•8 7 13 13
COMMENTS. This species differs from
the previously described species of Riedelites
because it is the only one with an extremely de·
pressed section and flaring almost annular ribs.
OCCURRENCE. Upper Aptian.
·
kJ:;:]i"'p;-P:A'HOPI:Ti,·t ·· ·
Genus \ Parahoplite'JJ An ffiula,- · ·"899
Parahoplites Anthula, 1899, p. 109.
\lliiiiL
rt oaq ttr ll'u )Uiiji'-G!Ejf¥
, .. " I
"9cW::-...Lc·:,
- .
TYPE SPECIES. Parahoplites melchioris Anthu·
Ia, original designation.
.E.. ahoalites (?} huba£hi n . .!!!.:
Pl. , fig.l.
Holotype. C-127 (U.N.C.M.H.N.C.P.Ht.N.54)
The description is based on the holotype.
The earliest whorl observed is the antepenulti·
mate. The umbilical wall is subvertical, the
umbilical rim is rounded. The ornament consists
of a regular alternation of emphasized primary
ribs which begin at the umbilical seam and flare
out slightly at the umbilical rim; the ribs appear
prorsiradiate up to the involution line. Between
these ribs there is a tapering intercalary rib that
disappears before reaching the umbilical rim,
this rib is inclined toward the primary preceding
it, but does not connect to it. This pattern
may be interrupted by a strong secondary rib
that reaches the umbilical wall but in these ca·
ses the primary ribs are much more prominent.
On the penultimate whorl the alternation of the
ribs is well established with the intercalary ribs
usually but not always extending to the middle
of the flank, then they cross the venter
'
in a wide
adoral arc.
A few primary ribs also bifurcate near the
umbilical rim. Beginning at the periventral margin
the ribs curve forward, so appearing wider
on the venter than on flanks, but they are not
flattened. At the beginning of the last whorl
a primary ribs bifurcates near the middle of the
flank. The shell is thick, the ribs are prominent
with symmetrical sides and rounded top on the
flanks, on the venter the adapical side of the
ribs is longer and more inclined than the adoral
side. Adaperturally the ribs have a moderate
biconcave profile that at times is nearly straight.
The venr is relatively wide, but the
maximum 'inflation of the whorl Is at the umbilical
rim. There is a striking development of the
umbilical wall from the penultimate whorl to
the apertural part of the last horl : at the be·
ginning it is subvertical to weakly convex but
it becomes retracted dorsally sloping toward
the venter of the preceding whorl .

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONlTES 73
The central branch of L of the suture has
tendency to become asymmetrical, usually
oser to the adumbilical branch.
b
DIAGNOSIS. This species is characterized
ui'rcalary ribs, the fanner stressed adumbil i ca­
· A) the regular alternation of primary and
IlY trom early in the ontogeny, B) its rounded
subrectangular whorl section and C) the change
in the inclination of the umbilical wall through- •
out the ontogeny, from subvertical to concave.
MllljUUrBDJBnt.l 0 Euw H W DfEuw D{H N.R.
"to %
c-127 757 26 32 ? 357 437 44
COl\'IMENTS. This species differs from
Pa rahoplites melchioris Anthula (1899, pl.S,
figs. 4,5) from Russia by the ribs .beg more
strongly flexuous and the whorl section ts lower.
The same species as illustrated by Sinzow (1907,
p.458, l)L2, fig.l) liewise as more flexuous
ribs thart the Colombian spectes. The topotypes
of Anthula's species illustrated by Casey (1965,
textfigs;146, f.g, h-i) emphasize the subquarlrate
whorl section of the type species.
OCCURRENCE. Unnamed beds above the
Socota Member and below the Capotes Member.
Upper Ap tian.
This species .is named in honor of the late
geologist Enrique Hubach 1 director of the Gelogical
Survey ofColombia trom 1950 to 1957.
Pczrohoplites hubachi n. sp.
P}; 5, fig.6; text-fig. 5F
··· (Morph I)
iParatype; (U. N. C. M. H. N. C. P. Pt. N. 59)
···- . •.. . - The innennost whorls are not clearly ob­
rvable ; The penultimate whorl is ornamented
"!ith.rlbs regularly distributed between primary
d Intercalary; the fanner begin at the umbili­
•.c: seam l1Jld they trend projected and at the
'W time they describe a feeble adoral conca­
tY on the adum))ilical third of the whorl side,
tqeyalso flange out and bifurcate. Between two
,:of -!H! primary ribs there may. be one or two
llirclllary ribs which begin at different points
'f• _in general the ribs are high with steep si­
PProaching the umbilical rim.
raterd
rounded but narrow top; they are sepa­
;·hlllr· by. lntercos spaces almost one and a
' · • as Wlde as the nbs.
>; _ _ '!'he earlist portion of the last whorl has
re:61vif umbtllc wall which rounds into the
::tnf'' J · _ attened s1des that likewise pass smoo­
' •irle
ityi Yteatned ven ter. Along the ventral
._._:lf\vh e . en_. bs are .
'•9owe 0
feebJyretracd. On the
no bircati?n of the nbs occurs,
·• ··;bet the adap1cal f the two intercalary ribs
fief
ore the ubllJcal rim but the adoral rib
an .-.--he. umbthcal seam. All the ribs are
·(' _Y tgh on venter.
NOTE : This morph is interesting because of the
decreasing in number of ribs from the
inner whorls to the outer ones and
their appearance at different levels.
Meuurement D Euw H W D/Euw D{H No.R.
% '%
c. 127 36 14 16 14 39 41 39
COMMENTS. This morph differs from
Parahoplites melchioris Anthula as illustrated
by Glassunova (1953, pl. II) because the whorl
section of the Caucassian fornt is more circular
and the ribs are more strongly projected anteriorly
on venter, but it lacks the retraction of
the ribs along the ventral median line.
Parahoplites multicostatus Sinzow (1907,
p. 459, pl. 2, fig. 5-7) has a whorl section inflated
on the adumbilical third of the flank and
convergent on the adventral third but on the
Colombian species the whorl section tends to
be slightly compressed; the bifurcation of the
primary ribs ceases earlier in the ontogeny of
the Colombian species than the Caucassian fonn.
OCCURRENCE. Upper Aptian.
Pa r;.a{l,oiJ, Pi. , 1ig. 5; Text-fig. 5G.
lite$..trWrul.. n. sp.
Holotype . C-127 (U.N.C.M.H.N.C.P.Ht.N. 55).
Paratype . C·l27 (U.N.C.M.H.N.C.P.Pt.N. 60).
The description is based on the holotype,
The protoconch can not be observed; the second
whorl is smooth but under high magnifi·.
cation broad puckers are indicated on the test
near the involution line; at the beginning of the
third whorl rounded ribs are visible, the latter
differentiate into primary and intercalary ribs
at the beginning of the fourth whorl, the primary
ribs appear at the middle of the umbilical
wall whereas the intercalary ribs begin near the
umbilical rim ; at this stage the ribs are blu t1
not very high, they are separated by intercosw
spaces slightly wider than the ribs.
The umbilical wall is rounded and passes
into the slightly convex flank. At the beginning
of the last whorl (4th?) the ribs develop a slight
concavl ty on the urn bilical wall and slight conve·
xity on the central third of the flank, then
describe a concavity on the adventral third and
project on venter where they widen in a visor­
like fashion. At this point the whorl section is
as high as wide with the maximum width at the
umbilical margin but there is a constriction of
the flanks along the periphery giving the whorl
a stubby pyriform aspect. On the last whorl the
primary ribs flange out on the ad umbilical third
of the flank.
The suture line (Paratype, N.60 ) has L
weakly asymme trical E{L and L/U2 are sub­
symmetrically bifid.
DIAGNOSIS. This species is characterized
by: A) its small size, B) its pyrifonn whorl sec­
t i on and C) the regular alternation of primary

74
and intercalary ribs, broadening on venter in a
visor-like manner.
Meuurement D Euw H W D/Euw D/H No.R.
% %
C-127 28 10 9 8 43 39 38
C-127 20 9 7 7 45 36 47
COMMENTS. This species resembles "Parahoplites
numidicus Sornay" from the "Zone
de Clansa r es. Djebel Harraba, anticlinal de Sidi
Embarka' , Algeria (Somay, 1955, p. 13, pl. 1,
fig. 16, 18) but the African species has a clear
alternation of ribs on the middle third of the
flank that does not occur on the Colombian
species, furthermore the whorl section of Sornay's
species is much higher than wide at comparable
diameters (see pU, fig. 18, op. cit.). Both
species however share in common the constric·
ted periventral margins and the maximum inflation
of the whorl at the umbilical rim.
OCCURRENCE. Unnamed beds above
the Socoti Member and below the Capote&
Member. Upper Aptian.
Pqrahoplites (?) inconstans Riedel ?
Pl. 10, fig. 2; Text-fig. 5D.
1938 Parahoplites inconstans Riedel, p.32, pl.6,
figs. 8-10, pl. 12, fig. 11, pl. 14, fig. 13.
1949 Parahoplites inconstans Riedel, Stoyanow,
p. 99.
1957 Parahoplites inconstans Riedel, Biirgl, p.
135.
.
1964 Parahoplites incostans Riedel, Etayo-Ser·
na, p. 118.
1965 Parahoplites inconstans Riedel, Biirgl, in
Campbell and Biirgl.
Holotype. Specimen described and illustrated
. . by Riedel, 1938, p.32, pl.14, fig.13.
Type locality. Quebrada Negra , al sur de Utica
Hypo type .qsJf1:rM.N .C.P.HyNi) .
Only one specimen is available. The whorls
are slightly higher than wide; the umbilical w,all .
is subvertical, it rounds into the flanks; the
intercostal proflle of venter is rounded; the
flanks are almost parallel to slightly inflated near
their middle. The ribs are strong and rounded,
they begin at the periumbilical margin, they are
almost rectiradiated though on the adventral
half of the flank they are slightly arcuate adora·
lly and cross the venter normal to the median
line where they . are ·'Slightly flattened. On .the
internal mold the ribs show delicate compressed
nodes along the umbilical margin. At the
periventral margin the ribs fonn rounded shoulders.
The ornament is composed of alternating
primary and seconday ribs, the latter beginning
slightly adumbilically to the middle of the flank.
The innermost part of the conclr$hows- two iri-
F. ETA YO • SERNA
tercalary ribs between primaries but usually
there is only one. The intercostal spaces are one
and a half times as wide as the ribs.
Meuuremente D Euw H W D(Euw D(H No.R.
% %
c - &03-13 28 12 9 8 43 32 21(3/4)
COMMENTS. On Riedel's illustrations,
that which depicts the complete specimen (Rie·
del, pl. 6, fig. 8) gives the impression the ribs
were delicat&Dy nodose along the ventral margins,
but this is not discernible on the ventral view of
the same specimen (ibid., fig. 9}. His specimen
· is larger than the present specimen. This is the
first time the stratigraphic occurrence of this
species has been documented.
OCCURRENCE. Unnamed beds above
the Socoti Member and below the Capotes
Member. Upper Aptian.
• ,·-· _"i _liG ___
.o_t:l._p·-"i-RA.... TIDABr' .. .,
Genus e· tiTikDIWZ&mtrweumayr and
Uhlig, 1881. . -
TYPE SPECIES. Ammo-nites · pierdenalis - von
Buch.
.Eneonocergs Q]galucicw.,n. sp.
Pl. it, fig.4; Text=figs. BB,SC.
Holotype. C-501A (U.N.C.M.H.N.C.P.Ht.N.56).
The section of the first whorl is depressed
and much wider than hightit hm a broadly rounded
venter; the second whorl is roughly subglobose,
the umbilical wall is oblique and rounds
evenly into the convex umbilical third of the
flank; the width of the whorl decreases and the
sides converge toward the slightly arched venter.
On the third whorl there is a marked increase in
the whorl height (H:6mm; Euw:2) and the section
becomes lanceolate: the flanks are nearly
evenly convergent toward the venter with a
slight compression on the adventral fourth; the
flanks join fonning an acute venter; the maxi·
mum inflation is at the umbilical third of the
flank.
Earch whorl overlaps the preceding one
to its umbilical rim. The ornament on the
fourth and last whorl consists of ribs which
raise as puckers at the umbilical rim and broaden
adventrally, they have a mammillate
tubercle on the umbilical rim (8 per whorl?);
toward the adapical half of the last whorl the
periventral carinae are serrate and bear outwardly
directed nodes.
The suture line has E/L wide, subrectan·
gular and ·has an internal branch, the other
saddles are entire, the lobes tend to be bi·
fid, only slightly indented.
D'IAGNOSIS. This species is characterized
by: A} its craterifonn umbilicus, B) its narrow
venter bordered by delicately dentate edges
1
and C) the puckers on the ·adumbilical third 01
the flank.
:;.

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 75
Meuurementa D Euw H W D/Euw D/H No.R.
'Yo %
C·61 0A 40 3 ? ? 7 ? 8?
COMMENTS. This species resembles Engonoceras
stolleyi Bohm {1898, pl. 5, fig. 3),
especially the juveniles attributed to that species
by Hyatt {1903, pl. 23, fig. 7-8, pl. 24, fig.
3, 4), but Bohm's species is more compressed •
·and has prominent ribs on the external half of
the flank; the opposite is true In the Colombian
species. At equivalent diameters the lobes
of the suture of the Colombian species are more
indented but they have fewer secondary elements
than in Bohm's species.
OCCURRENCE. Middle Albian.
Engonoras.P... .. .
Pi.*li, fli -g_
Reference specimen C· 510-A.
Only one specimen is available (D:42mm).
The conch is discoidal, compressed and involute;
the umbilical wall is subvertical, it grades into
the side through a rounded rim; the flanks are
slightly convex, gently converging toward the
venter; the maximum width is near the middle;
the venter is narrow, slightly concave, it is bor·
dered by two sharp dentate carinae, the teeth
corresponding on both sides of the venter.
• ·. · . . The ornament on the ad apical half of the
.
· lest whorl consists of bundles of lirae which
foi:tn taised and rounded inflations at the adum-
' iUc.al third of the flank; the ribs have a minute
> c;onical tubercle at the umbilical rim; they trend
Jn·orsiradiate or with a slight adoral bow to the .
:(adventral third of the flank where they form a
;,. crescentic adoral concavity.
., "'" · · · ·
Near the middle of the flank the ribs tri·
On the internal mold flat, low strapare
impressed, ending at the marginal
in clavi that are as wide as the ribs.
·· Slngl, non tuberculate intercalary ribs
occur. The intercostal spaces are shallower
ribs and are indicated by notches on
On the adoral half of the last whorl
.
develop very fine bullae near the urn­
.. riin and a conical tubercle near the mid·
the Dank and the carinal teeth become
The suture has subrectangular, bifid
specimen is septate 'up the adoral·
preserved.
·
"Parengonoceras elegans Renz.'-' (1970, p.
1036) from La Puya Member, Upper Albian of
Venezuela (Renz, 1970, pl. 3, fig. 1c especially)
has a similar type of ribbing, but its whorl section
is more lanceolate than in the Colombian
species at comparable diameters.
OCCURRENCE. Middle Albiali:·
_Encfl.or;:;

76 F. ETAYO · SERNA
p.171, pl.22, fig.6-10, pl. 23, fig. 1-6), especia­
lly to the holotype (ibid., pl.23, fig.1,2), but
the latter has a flattened tectifonn whorl sec·
tion, and a characteristically persistent deve­
lopment of the nodes along the middle of the
flanks at a diameter at which the Colombian
species is smooth.
This new species also has a slight resem·
blance to Protengonoceras gabbi (Bohm) in
Hyatt (1903, p.154), but the latter lacks tubercles
throughout the ontogeny and has a distinctly
concave venter which seems to be rounded
in extreme age (op.cit., p.155). The lobes of the
suture are somewhat similar but they are
more lacerate in . the Colombian species.
OCCURRENCE. Upper San Gil Formation
(Bed 8). Middle Albian.
This species is named in honor of the late
field assistant J. Duarte, of the Geological Sur·
vey of Colombia.
-k .... '!"':"'-,-J-t!- .:.;'->· -·.-· •, ..... ,.,.,._._ ... ,- • ·
.
\ Genus ( PlatiknemiceradBata11er,
.
195.
Platiknemiceras Bataller, 1954, p.174.
TYPE SPECIES.Knemiceras (Platiknemiceras)
bassei Bataller, original desig·
nation.
Pigtikneuriceras colombianq _
PAP.lL:tEt:J.
Holotype. C-169 (U.N.C.M.H.N.C.P.Ht. N.58)
The conch is discoidal, involute. The um·
bilical wall is vertical and has a blunt umbilical
rim; the ·adumbilical half of the flank is flat
whereas the adventral half converges evenly toward
the narrow, flat to slightly excavated ven·
ter; the periventral margins are sharp, they have
·
finely crenate carinae on each side.
The surface of the shell is covered with .fl.
ne, periodically raised lirae which gather in
bundles producing very low falcate ribs visibl.e
only with oblique illumination; they are radial
and straight on the adumbilical and cetral
thirds of the flank but on the adventraljhird
they describe a shallow adoral concavity . \.
There is an alternation of moderately ac·
centuated and ofvery·low ribs. On the adventral
third of the flank feather structure is visible on
both flanks. On o.ne side on the umpilical
brink there is a tenuous fain t bullate tubercle (?).
DIAGNOSIS. This species is characterized
by: A) Its fm ely crenate ventrolateral carinae, B)
the trend of the bundles of lirae, radial n the
central and adumbilical thirds of the flank, ado-
·
rally concave on the adventral third.
Meuuzementa.
c- 189
' D
?
Euw
5
H
30
W .
14
COMMENTS. I am following Casey's (1961)
interpretation of Platiknemiceras. Of the species
referred to this genus by Casey, Platiknemiceras
gracile (Douville') (1916, p. 128, pl. 16, fig. 9,
text- fig. 42) looks similar, however, it seems
more inflated and has more elongated and pro
minent crenations on the ventrolateral carinae.
J:p-tiknpr:-icera$ f.e· ind. A.
eX"tigs;·81t;"8K7 w:.L,. ...
Reference specimen C • 51 OA.
The conch is involute, discoidal, the sides
are almost flat to weakly convex, there is a conspicuous
beveling of the adventral fourth of the
flank.
The ornament consists of flat; rib-like
bands that begin as bundles of growth striae
with a slight concavity on the umbilical rim, they
trend prorsir&diate up to the adventral third of
the flank from where they describe a crescentic
adoral concavity to the venter. The intercostal
spaces are thread like.
The venter is slightly concave and bordered
by two sharp carinae. A sligh tly larger specimen
shows the suture, it has the external ele·
menm ordered in an almost vertical echelon. On
the adult (?) a weak median carina along the
ventral line is observable but otherwise the ven­
'ter is flat although the periventral carinae per·
sist. The growth lines cross the venter nonnal
to the median line.
NOTE: This species is characterized by: A) the
subparallel nature of the flanks with
the beveled adventral fourth, apparen·
tly persistent throughout the ontogeny,
B) its falcate, pucker-like low !'ib·
bing, and C) the tendency to develop a
ventral median carina with growth.
Meuurementee. D Euw H W D/Euw% D/H %
C-610A 17 3 10 6 18 69
COMMENTS. An unfigured species of
Platiknemiceras (?) was noted by Breistroffer
(1952, p. 2634) as occurring with Knemiceras
in the ."Mesoalbien basal du Cundinamarca", the
characteristic suture described by Breistroffer
agrees in general with that of the present species.
The suture of the type species of Platiknemiceras
(see Bataller, 1954; Casey, 196l, fig. 1b)
has shallower accessory lobes than the Colom·
bian species.
OCCURRENCE. Middle Albian.
W.ol;flf[if?ll&:JPE:P
Reference eeimen. V. L. Est. 33a, bed 8.
Only a fragment of the internal mold of
this species is available. !The conch in discoidal,
the whorl section is evenly convex. The surface
of the internal mold is smooth; locally and only

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 77
visible with oblique illumination there are very
tenuous, rib-like radial pleats.
The venter ls flat to slightly excavated, it
is bounded by two rounded, apparently continuous
carinae that are broadly ondulated.
NOTE : This species is characterized by its broadly
wavy carinae and extremely atte- •
·
nuated ornament.
MEASUREMENTS. The specimen has a
radius of 90 mm but no other measurement can
·
be made.
COMMENTS. This species is rather simi·
lar to that illustrated by Casey (1962, P,· 355,
fig. 1c, ld) as Platiknemiceros sp . from ' Lower
Albian (sandy siltstone at base of Group 5) near
Canta, Peru:' It is possible that this fragment
, from Est. 33a represents lhe adult ofP. colombiano.
OCCURRENCE. Upper San Gil Formation
(Bed 8 ). Middle Albian.
:tan· T!feitic;;J!;};i -
Knemiceras Bohm, 1898, p. 200.
TYPE SPECIES. Ammonites syriacw von Buch,
original designation.
netW'af semicostatum
oromemw@ . .; • .ft_ll
Text-fig. 8G, 81.
•.. fig. 2;
19l0Knemiceras attenuatum var. semicostatum
Sommermeier, p. 350, text-fig. 18
? 1947 Knemiceras semicostatum Sommermeier,
Knechtel, p. 93, pl. 15, fig. 1, 2, 3, textfig.
3.
1952 [Knemiceras l semicostatum Somm., Breistroffer,
p. :2633.
) 1952 Kn. [emiceras l semicostatum Somm.,
·
Mahmoud, p. 8'4.
? . 1955 Kn. (emiceras ] attenuatum semicosta­
· ·
. . . tum . Sommermeier, Mahmoud, p. 54,
fig. 27.
'?1964 Knemiceras attenuatum semicostatum
Sornmermeier, Etayo-Sema, _ p. 121.
?1965 Knemiceros semicostatum semicosta-
.
tum Sommermeier, BUrgi, in Campbell
and BUrgi.
19S.S Knemiceras semicostatu Sommermeier
· ·
Etayo-Sema, p. 37, fig. 9, Tab. I.
lipotype, V.L.Est. 33a, bed. 8 (U.N.C.M.H.N.
· C.P.Hy.N.42).
r/Pe. · • The decption is based oi! e ypoty-
1, the
conch ts tyolute; the umbilicus JS dep,
;,;_;: .· 0 que umbthcal wall grades evenly mto
the convex sides. The whorl section is inflated
on the adumbilical third of the flank, it is sllghtly
compre!ISed to excavated on the adventral
third, the venter is truncated.
The adapical portion or the last whorl
of this specimen has broad low ribs which arise
from sharp periumbilical tubercles, they trend
radially up to middle of the flank from which
point they describe a feeble concavity to end at
elevated spinose periventral clavi. At the adapi·
cal segment where the shell is preserved these
nodes are interconnected by a zig-zag rib.
An intercalary rib begins in .. a subdued
manner near middle of the flank ·and near the
following adoral primary as if bifurcating from
it, it terminates in a spinose ventrolateral tubercle.
The periventral tubercles alternate.
The living chamber is half the length of
the last whorl; no appreciable change in the ornament
occurs except for the attenuation of
ribbing and increase in spacing between the periumbilical
nodes (6 per whorl). Flexuous growth
lirae are present on the exterior of the shell
where it is preserved.
DIAGNOSIS. This species is characteri·
zed by : A) its moderately inflated, rather pyriform
whorl section, ll) the alternation of low
sinuous ribs, the primary ones beginning at sharp
periumbilical tubercles, and the secondaries be·
ginning near the middle of the flank where the
primary ribs are slightly inflated.
Measurements. D Euw H D/Euw% DJH %
V.L.Est. 33 81 17 40 21 50
COMMENTS. The present specimen is
very similar to the one referred to the "variety"
(op. cit., p. 351) and illustrated by Sommerme·
ier; the other specimens referred to the same
variety by him as well as those illustrated by
Knechtel (194 7, p. 93, pl. 15, figs. 1, 2, 3), have
strm.ger rounded ribs than in the Colombian representatives.
Knechtel's specimen also has more
numerous ventrolateral tubercles.
OCCURRENCE. Upper San Gil Formation
(Bed 8). Middle Albian.
.. Knemiceros
f
egnai n. SE·
.J!J;2, ftg.J. iett·tt!t!• so! ..
... ..
Holotype. C-131 (U.N.C.M.H.N.C.P.Ht.N.59).
Only the holotype is available, it is septate
throughout. The innermost whorls have
flat, subparallel sides and excavated venter. The
subsequent whorls acquire a Ianceolate section
with flat venter; the last stage has subparallel
sides which merge smoothly ir.to· the arched
venter; the umbilical wall is subvertical, short
and rounds into the flanks without a definite
rim. The involution line follows the external
margin of the periumbilical tubercles.

78
The sculpture consists of fold-like pro·
minent ribs which converge toward a prominent
spiny umbilical tubercle ; the ribs are arranged
as a trident: one adapical rib that reaches the
umbilical rim but without joining the umbilical
tubercle, a very short rib dying without reaching
the middle of the flank ll!'d in line with the umbilical
tubercle, and one adoral rib that extends
toward the umbilical rim; both the adapical and
adoral ribs bear a sharp tubercle in the middle
of the flank; all ribs terminate in rounded peri·
ventral tubercles. Between these groups of ribs
there is a short intercalary.
On the adapertural half of the last whorl
the umbilical tubercle is connected to the ad·
ventral tubercle by a ridge-like rib, whereas the
other ribs tend to fade out. There are six peri
umbilical tubercles.
DIAGNOSIS. This species is characteri·
zed by: A) its ontogenetic change in whorl sec·
tion from sublanceolate to subovate B) the
changing emphasis of the tubercles, in decreasing
order, periumbilical, centro lateral and periven·
tral respecetively, C) its large and robust appearance.
Meuuremeats. D Euw H W D/Euw% D/H%
C•l31 177 46 81i 66 27 48
COMMENTS. In ornamentation, this
species is similar to Knemiceras raimondi Liss6n,
as that species has been interpreted by Benavi·
des-Caceres (1956, p.45 3, pl.48, figs . 1-5, text·
fig.39), but the ontogenetic change of the whorl
section is retarded in the Colombian species
which attains a greater diameter and thorn-like
tubercles, unlike the Peruvian species . .
.. Knemiceras raimondi tardum Benavides
Caces (1956, p. 455, pl.48, fig. 6-7, text-fig.
40), i;etains the sublanceolate or . triangular
whorksection longer than K. raimondi s.s. but
it changes earlier in the ontogeny than the Co·
lombian species.
Breistroffer (1952, p. 2634) recorded
from Cundinamarca ''K. [nemiceras]'Raimondii
Liss., tres trituberculise, .--: ." but np iUustra·
tion is available. K. pegnae also resebles Am·
monites ebrayi de Loriol (1882, p.7, pl.l, fig.1),
type species of Parengonoceras Spath (1924),
but de Loriol's species has a higher whorl section
and a narrower venter than the Colombian spe·
cies, and its ribbing has a purely radial arrangement.
OCCURRENCE. Middle Albian.
This species is named in honor of the
field assistant Luis F. Pefia of the Universidad
Nacional de Colombia.
·Family BRANCOCERATIDAE
!:Oeii\i&r"(]nc'.fm(cer§n. g. :: f'"'.(""'"'r_,..o_..
\., .. , ·
_ ... ..
...
·-.-.,.,., .. Y1i;t:'l-'" 4....- .•.u.;.o... · .o -....: """'-'·--"'"
TYPE SPECIES. Rinconiceras rinconi n. sp.
F. ETAYO· SERNA
DIAGNOSIS. Many whorled conchs;
early whorls depressed, smooth; juvenile whorls
with transient rounded umbilical tubercles from
which ribs may arise ; the venter progressively
becomes acute and the ribs become accentuate·
dly falciform on the flanks, well spaced and ar·
ched adorally on venter.
COMMENTS. As for the type species.
This genus is named in honor of Profes·
sor Luis F. Rincon, curator of the Museum of
the Geological Survey of Colombia.
.Rir!l.i':inconi q . .m..
-pr.;: fig;ext-figs. sv, sw.
Holotype. C-169 (U.N.C.M.H.N.C.P.Ht. N. 60)
Paratype . C-169 (U.N.C.M.H.N.C.P. Pt. N.62)
The conch is multispiral and evolute;
the inner whorls were studied on one paratype
(C-169·2). The protoconch is about 0.05 mm in
transversal diameter, spindleform and the whorl
section is crescentic through the first and second
whorls the wh or1 section breomes progressi·
vely more inflated but the crescentic profile still
persists; on the third whorl the section is almost
as high as wide, its maximum width is at the umbilical
rim and it has a narrowly arched venter;
on the fourth whorl the flanks flatten, the whorl
has a vaulted section and the arched venter broa·
dens slightly; on the fifth whorl the flanks are
planar, they grade evenly into the rounded urn·
bilical wall, and the venter is slightly flattened
with broadly rounded periventral margin.
The first three whorls are apparently
smooth (with weak constrictions?), on the
fourth whorl {paratype C-169-1}, conspicuous,
transvenely elongated tubercles develop along
the periumbilical rim (six per whorl on speci·
men C-169-3), they are widely spaced ; between
the prominent tubercles there are one or two
minor tubercles. Both major and minor tuber·
cles correspond to the point of origin of the
prominent ribs. On the sixth whorl the ribs
begin at the umbilical rim and trend almost ra·
dially up . to the periventral min from which
point they widen on venter describing a weak
chevron-like bend on the adapical portion of
this last whorl. However, most ribs seem to
start tangent to the umbilical rim, they then
describe . a weak adoral arc on the ad umbilical
half of the flank and a weak concavity on the
adventral half. The primary ribs start at the
umbilical rim whereas the intercalary ribs start
slightly a9umbilically and in a subdued manner.
B) Up to 35 mm. The early development
is as previously described, but on this specimen
the periumbilical tubercles of the fifth and
siXth whorls are strongly developed. Near the
beginning or the living chamber the whorl
section tends to become fastigate and the ribs
accentuate their cumture becoming falcoid
and well projected on venter, they have a welldefined
chevron-like adoral arch. The living
chamber is a third of the last whorl, with

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 79
sinuous ribs that have a wide concavity on the
adventral half of the flank.
::•;, ,,, ' DIAGNOSIS. This species is charadiri·
zed by: A) the change in its whorl section
:through the ontogeny from depressed to subfas·
- tigate, B) the ontogenetic development of'the
ornament from smooth whorls (with constrictions?),
to whorls covered with rectiradiate ribs, •
and finally, with sigmoidal ribs with progressive
stressing of the external adoral concavity, C)
the rounded ribs and the wide intercostal spaces.
Measutementa D Euw H W D/Euw04 D/H % No.R.
C-169·1 28 13 11 9 46 39 25
C·169·3 34 17 12 10 50 35 21
COMMENTS. The ontogenetic development
of this species is characteristic: it does not
develop a keel at any stage, and its inner whorls
• have a widely arched venter, however, in the
latter stages the whorl section is acute ogival.
The absence of acute inner whorls separates it
from Brancoceras Steinmann (1881) and the
same characteristics separate it trom Hysteroceras
Hyatt (1900), ll'owever, the presence of
transient tubercles and the chevron-like projection
of the ribs on venter tend to give it a Hysteroceras-
!ike appeazance (compaze fig. 4, on
plate 9 of this paper with Hysteroceras aff.
d'Orbigny Spath, 1934, p.486, text-fig. 169).
The presence of rounded tubercles and
the tendency to sharpening of venter with the
strong projection of the ribs on venter differentiate
Rinconiceras rinconi n. sp. from Eubrancoceras
aegoceratoides (Steinmann), type species
of Eubrancoceras Breistroffer (1952).
The Colombian species also resembles
Brancoceras (?) carinatum Collignon (1949,
p.95, pl.20, figs.5, 5a, 5b) type species of
Paroxy tropidoceras Breistroffer (1951, p.267,
nom. nud.); the Madagascan species has a true
carina whereas in the Colombian species the
ven ter is merely sharpened on the adult and the
species is in general more evolute.
OCCURRENCE. Middle Albian.
-·Family L YELLICERATIDAE
, .
9-::r
r;!!!E!Is
th: -
Lyelliceras Spath, 1921, p. 220.
1921.
TYPE SPECIES. A. Lyelli Deshayes in Leyme·
rie according to Spath; original
designation
Ll!jqicez:g cP·
£. fis. ; ix:::Jis.Ji, s.
olotype. C-255 (U.N.C.M.H.N.C.P. Ht. N.61)
aratype. C-225 (U.N.C;M.H.N.C.P.Pt. N.63,64)
Up to 11 mm D (C-225·1). The fllS t two
, Whorls are apparently smooth; on the adapical
.. • Part of the third whorl there are very well mar-
ked sigmoid&] folds; shortly a strong acute rib
appears at the periumbical rim, beginning with
a compressed bullate nodeand ,exapd up to a
subtriangular tubercle in the in'i"mtt e of the
flank; from he cenal ercles tq the periventral
margin the nbs wtden an--flatten and
describe a crescentic shaped concavity to end at
a clavate periventral tubercle; at this stage of
growth the ribs cross the fastigate venter as several
riblets that form acute "Vs". Between these
ribs there may be one or two intercalary ribs
which do not reach the umbilical third of the
flank, the latter appear like handle-less sickles,
but theY, are slightly less prominent than the -primary
nbs. There are five primary ribs on the
third whorl. The whorl section is ovate, higher
than wide, with obtusely beveled venter along
which a wavy weak carina develops. In general,
the ribs form an elongated angular S on the
flanks .
Up to 23 mm D {C-225). At the adapical
portion of the fourth whorl, a weak bituberculate
intercalary rib extends to the periumbilical
rim is still visible but from that point on there
are no intercalary ribs. The ribs have a more or
less accentuated polygonal profile; they begin
at the middle of the umbilical wall and lead to
the conical periumbilical tubercle forming a narrow,
hih and acute prorsiradiate segment; the
periumbtlical and centrolateral tubercles are
connected by slightly wider almost rectiradiate
segment of the rib, and from the latter tubercle
to the periven tral tubercle the ribs are still wider
and are slightly prorsiradiate, the strong ribs
cross the venter almost normal to the ventral
median line or with a light adoral acute arc. The
involution line is immediately above the conical
centrolateral tubercle. The tubercles along the
ventral median line are clavate and tend to be·
come conical. The whorl section is rounded
subquadrate. There are 16 ribs on the venter of
the last whorl. The intercostal spaces are 2.5 times
as wide as the ribs and are flat bottomed.
C) Up to 43 mm D (C-255). The medium
size f!)ecimen selected as holotype, has the abo·
ve characteristics with the interrupted rib profi·
le mostly when the cen tral portion of the rib
becomes strongly rursiradiate. The intercostal
space varies from two to four times the width
of the ribs on the internal mold. There are 19
ribs on the last whorl.
DIAGNOSIS. The species is characterized
by: A) the eazly development of strong, acute
and widely spaced ribs that in longitudinal profile
appear as an elongated angular S, B) the
presence of adumbilical and adven tral lateral tubercles
on the ribs, the latter the most prominent.
Measurements D Euw H w D/E•Jw D/H No.R.
% %
C·225·1 11 5 4 ? 45 36 8(1/2)
C-225 23 10 87 8? 43 36 16
C·225 43 21 13 12 48 30 19
COMMENTS. This species differs from
Lyelliceras lyelli (Leymerie MS), in d'Orbigny

BO
(1841, pl. 74) as interpreted by Spath (1931,
p.315), by the more depressed whorl section
and rectiradiate ribs of that species. Breistroffer
(1952, p. 2634) has recorded "Lyelliceras Lye­
IIi Desh. sp." from Boyaca, but his unillustrated
record may not be relied upon; the specimens
from Pen! referred to Lyelliceras 11elli (Leymerie)
d'Orbigny, by Benavides · Caceres (1956;
p. 463, pl. 51, figs.2,3), differ from the European
forms, as observed by Young (1966, p. 18),
because "the ribs . .. are sharper . .. ". The Peruvian
taxon though more similar to the Colombian
forms than to the European, has coarser
ventral tubercles.
e{liceras fNifolY.,elli,orme n. sp.
" ' "' '·
BE:
:g-;·'hf."§, . -ti{.
Holotype. C-255 (U.N.C.M.H.N.C.P.Ht. N.62)
Paratype. (U. N. C. M. H. N. C. P. Pt. N. 65)
A) Up to 20 mm D (C-225). The adapical
part of the second whorl is smooth, the intercostal
whorl section has convex sides that tend
to form a fastigate venter, they merge smoothly
into the oblique umbilical wall, the adoral seg·
ment of the second whorl has broad pleat-like
ribs separated by wider intercostal spaces; on
the third whorl the ornament is characterized
by strong sharp ribs t!tat begin at the umbilical
rim, betweeen them there is a concave intercos·
tal space with an intercalary rib appearing near
the middle of the flank side. A conical centrola·
teral tubercle is present on the primary ribs at
the line of involution. On the fourth whorl
(D:20 mm) the ornament consists of club-sha·
ped convex ribs with three tubercles: one
mammiform along the umbilical rim, a second
more prominent and conical just adventral to
center of flank and a third, clavate and still mo·
re prominent, at the periventral margin . At this
stage all the ribs are equally strong although the
intercalary ribs may have the umbilical tubercle
very reduced or occasionally do reach the umbilical
rim; the ribs widen on the venter and
cross normal to the median line, they are surmounted
by a prominent clavate tubercie . The
intercostal spaces are slightly wider than the
ribs on the flank but narrower than the ribs on
the venter.
B) Up to 37 mm D (C-255). There is no
change in the pattern of ornamentation; the
whorl section is rounded subquadrate, slightly
wider than high. When the shell is preserved the
ribs seem to attenuate. The position of the tu·
bercles on the whorl section migrates slightly
outwards throughout the ontogeny.
DIAGNOSIS. This species is characterized
by: A) the ontogenetic development of the ornament
during which the intercalary ribs beco·
me as prominent as the primary ribs, B) the
coarse, club-shaped ribs that describe a broad
adoral arc on the flanks, C) the rounded sub·
quadrate whorl section in the adult.
F. ETA YO · SERNA
Meuurements D Euw H W D/Euw D/H No.R.
., %
C·266 20? 8 7 7 40? 36? 9(1/2)
C-266 37 18 13 14 48 36 20
COMMENTS. This species resembles Lye·
l/iceras pseudolyelli (Parana and Bonarelli)
[1896, p. 99, pl. 5, fig.2], especially the speci·
men from Escragnolles (France) which Spath
(1931) suggested should represent the species in
the restricted sense, rather than the specimen
referred to the same species by Spath (1931,
p.319, pl. 32, fig. 14a, b; 15a, b). In the Colom·
bian species, however, the ornament is coarser,
the clavi along the ventral median line are very
prominent and the whorl section is quadrangular.
The specimen described by Riedel (1938,
p.54, pl. 9, figs. 5, 6; pl.13, fig. 16) as Lyelliceras
pseudolyelli Par. 8, Bon., has a compressed
section and its ribs are adorally concave, however,
it could fall withing the scope of the new
species. It should be noted that on Parana and
Bonarelli's figure 1b-lc of their plate 14 the juvenile
does not seem to have a fastigate venter
as in the Colombian species.
OCCURRENCE. Middle Albian.
Lel/iceras isaac/eai n. S£:., ..•.
·
Pert, ng. 1.
Holotype. C-255 (U. N.C.M.H.N.C.P.Ht.N.63)
A) Up to 11 mm D (C-255). The early
ontogenetic development was studied on several
small specimens whose growth stages overlap,
however, because no intermediate stages be·
tween them and the adult holotype were found,
they are not considered adequate for specific
determination even though their aspect seems
characteristic; their description is present as a
contribution to the understanding of the genus.
The first and second volutlons following the
protoconch have a whorl section which tends
to be circular but has a wide and oblique umbi·
Iical wall; on the adventral fourth the flanks
flatten and converge toward the venter to form
a low but distinct carina; at this stage the only
ornamentation clearly visible is growth lines
that describe a concavity on the umbilical wall
and an elongated adoral arc on middle of the
flank, .

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 81
distance between the ribs varies from two and a
half times the width of the ribs.
B) Up to 60 mm D (C-255). The inner
whorls of this specimen resemble those of tile
1atgest or the previously described specimens.
1n the holotype the centr third of the flk
has two tubercles: 1) a moderately developed
ovate tubercle at the boundary of the adumbili·
cal third or the flank 2) a similar but more conical
tubercle developed at the boundary with
the adventral third ; there is a third clavate tu·
bercle that grows outwards from the periven·
tral margin. The tubercles are equidistant.
Along the ventral median Une there is a row o(
clavate tubercles that correspond to the peri·
ventral tubercles but are more raised. .
•.
On the in tern a! mold the ribs seem to be·
gin near the middle of the umbilical wall; the
ribs are sharp adumbilically but become
wider and flattened towards the periventral
·margin; the ribs cross the venter as a wide band
normal to the median line and have a tendency
to split.
The intercostal spaces are as wide as the
ribs on venter, they become progressively wider
toward the umbilical wall; the umbilical wall is
inclined.
DIAGNOSIS. This species is characterized
by: A) the slow development of the omamenta·
tion, B) the distribution of the tubercles on the
ribs outside the umbilical rim and their increa·
sing prominence toward venter, C) the subrec·
tangular whorl section with strong inclination
of the umbilical wall.
Meuurements D Euw H W DfEuw D/H No.R.
% %
C·255 60 28 22 20 47 37 26
COMMENTS. This species differs from
"Lyelliceras ulrichi Knechtel" (1947, p.99, pl.
23, fig.1a. lb; Benavides Caceres, 1956, p.464,
pl.51, fig.4,5,6,7 ,; see next genus), by the ra·
pid development of a coarser, straighter and
uniform ribbing in the Peruvian taxon, the lat·
ter almost lacking any indication of adumbili·
. cal lateral tubercles. Lyelliceras pseudolyellifor­
!"le n. sp. differs by its rounded subquadrate
whorl section and strong arched ribs developed
early in its ontogeny.
OCCURRENCE. Middle Albian.
tral to prominent ventrolateral clavi ; ventral
median clavi corresponding to the ventrolateral
ones; · ·-- ·· ·-
COMMENTS. The genus diffeJrom Prolyellicer!IS
Spa (1930), "{ hi

82
lop along the ventral median line. At a diameter
of about 15 mm, the sculpture becomes conso·
lidated, the ribs widen adventraly, but they continue
to be falcoid.
The ribs are flattened on the adventral
third of the flank and cross the venter, although
much attenuated. Some ribs swell periumbilica·
Uy, developihg a tubercle. The intercostal spaces
are widt;r than the ribs and the intercalary
ribs are irregularly distributed; the growth striae
..r-foUow the pattern of the ribs, on venter they
project and form a V with its apex pointing
ad orally. The suture lines has E divided by
asymmepical saddle.
)
B) Up to 110 m Q (-253, not collected
in situ). The ornament consiSts of strongly fle·
xuous ribs mostly primaries but occasionally
an intercalary rib arises from the adapical slope
of the next primary rib. When the test is preserved,
the ribs appear broadly rounded, and
although they are narrower on the internal mold,
they still appear rounded; the flattening of the
ribs between the internal lateral and the medial
tubercles produces sulcus-like depressions on
both sides of venter. The living chamber occupies
2/3 of the last whorL
. DIAGNOSIS. This species is characterized
by: · A) its robust aspect and subquadrate whorl
section, B) the strongly flexuous ribbing in young
adults that is straightened on the living cham·
ber, C) the development of ad umbilical clavi on
the early inner whorls and attenuation of the
inner lateral tubercles on the living chamber.
Meuurementa. t> Euw· H w DfEuw D{H No.R.
% %
In situ C-229 11 4 4 4? 36 36 12(1/2)
" 16 6 6 6 40 40 21· ·
19 8 8 8 42 .42 26
.20 9 8 7 46 40 21
7 13 12 13 7
ex aitu C-263 21 10 8 ? 48 38 21
c-253 •no 63 37 36 7 ? 'l6
COMMENTS. This species diffeiS from
Ralphimlayites prorsocuroatum (Gerhardt), be·
cause it has less falcoid ribbing throghout its
ontogeny, and develops ad umbilical bullae more
consistently. Breis troffer (1936, p. 156,157)
recorded "un Lyelliceras nov. sp. (gr, Gevreyi
Jacob sp.) assez voisin du L. prorsocuroatum
Guerh. sp. non R. Douv. sp. =.Prolyelliceros peruvianum
Spath) . .. ", apparently from the sa·
me region as the present specimens; subsequently
Breistroffei' (1952, p. 266) suggested the
association of Douvilleiceros solitae d'Orb. and
Prolyelliceras cf. Gevreyi. "Pro lyelliceras"gevreyi
(Jacob) (1907:..p.101 =A m. Lyelli, Leymerie, se·
conde variete', in Picted and Campiche, 1860, p.
198, pl. 24, fig. 7a, 7b), according to Pictet and
Campiche's text and figure, the conch is compressed
and high whorled (ib., p. 198, pl.24, fig.
7a), the ventral median clavi do not correspond
to the periventral ones (ib., fig. 7b).
F. ETA YO · SERNA
At comparable diameteiS both species ha·
ve a well marked adoral concavity of the ribs on
the adventral third of the flank.
OCCURRENCE. Middle Albian.
. ·· . . a-=·1!,-ocera3Y.-19
Tegoceras Hyatt, 1903, p. 84.
03
_
TYPE SPECIES Ammonites mosensis d'Orbigny,
original designation.
_Tgpc e{f!i..,be,navid£,scaceres£ .!1·
sp.
PI.l1, fig.8; Text-figs. 8Z, SZ'.
? 1956 Lyelliceras pseudolyelli Parona and
Bonarelli, Benavides-Caceres, p.463,
paiS., pl. 52, fig. 3.
non 1956 Lyelliceras pseudolyelli Parona and
Bonarelli, Riedel, 1937-1938, p.54,
pl. 9, figs. 5-6, pl. 13, fig.16, in Be·
navides Caceres, p. 463.
1968 Lyelliceras pseudolyelli sensu Benavides-Caceres
(non Par. Bon.) 1 Etayo-Serna,
p. 37, fig. 9, Tab. I.
Holotype. V.L.Est. 33a (U.N.C.M.H.N.C.P.Ht.
N. 65).
Only a single specimen is available. The
conch is evolute; on the ·adapical portion of
the last whorl the ribs egin in a su.bdued manner
near the umbilical rim, slightly later they·
tend to develop a weak bullae; just adventrally
to the middle of the flank the ribs develop a
small conical tubercle; from the umbilical rim
to the subcentral tubercle, the ribs are prominent
and rectiradiate or weakly convex adonijly;
on the adventral third of the flank the nbJ; des
cribe a concavity and become flatteed,.,:th.ey,
end at a very prominent outwardly directed
ventrolateral clavus.
Occasionally a rib starts higher on flank
than the otheiS. There are 24 ribs on the last
whorl. On the adoral half of the last whorl the
ribs look like broad folds. The intercostal spaces
are slightly broader than the ribs on the in·
temal moid, subequal when the test is preserved.
The whorl section is higher than wide,
and is truncated pyrifonn, with· the maximum
inflation near the boundary between the adumbilical·
and central thirds of the flank. On the
venter there is a row of low clavi along the ven·
tra! median line.
The ribs• do not oppose each other but alternate
from one flank to the other. The umbi·
Jicalwall is short, inclined and rounds into the:
flank.
.
..
DIAGNOSIS . . Tbis species is characterized
by: A) its sinuous, club-like ribs, B) its ven"trally
truncated pyriform whorl section.

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 83
Meuurementl. D Euw H W D(Euw D/H No.R.
"fo %
v. L. En. 33a 80 32 31 1 40 39 24
" at 1 1 22 16 1 1 ?
COMMENTS. This species resembles
-,"Acf1pthocems Seunesi Parona and Bpnare_lli"
(1897, p. 100, pl. 5, fig. 9 =18goceras)., a more
evolutesp.ecles than T. camatteanum (d Orbigny),
but Parona and BonareUi's species has a more
rectangular whorl section than the Colombian
species, furthennore, the former Is more spuse·
ly and strongly tuberculated.
The specimen figured by Benavides.C&ceres
(1956, pl. 6,.3', fig. 3) greatly resembles the
Colombian specunen even in the pattern of the
suture line, but L is narrower on the Peruvian
species. In my opinion the whorl section of the
Peruvian separates it lrom Lyelliceras pseudolyelli
Parana and Bonarelli.
OCCURRENCE. Upper San Gil Formation
(Bed 8). Middle Albian.
This species is named in honor of the Pe·
ruvian geologist Dr. V.E. Benavides·Caceres.
TYPE SPECIES. Lyelliceras scheibei Riedel,
1938, p. 55, pl. 9, fig. 7' 8;
pl. 13, fig. 17.
DIAGNOSIS. Homeomorph ofLyelliceras
Spath (1921) in its early development; very evalute,
the whorl section changes from reniform
in the early whorls to vaulted in the intermedia· .
te stages to subrectangular with flat yaullel sides
in the adult; the living chamber o the adult
tends to become rounded.
The early whorls are smooth, the subse·
quent whorls have straight ribs that appear as
if bifurcating in a V fashion from periumbilical
tubercles; on the living chamber of the adults
the ribs are biconcave .
All primary ribs bear, A) a periumbilical
mammillate tubercle, B) a clavate to acute periventral
tubercle, C) a ventrolateral clavus, and
D) a conesponding ventral median clavus. On
the living chamber of large specimens the
tubercles tend to disappear. The suture line has
wide subrectangular, subsymmetrical saddles, L
·
is dominantly bifid.
COMMENTS. Codazziceras differs from
Protacanthoceras Spath (1923) because it has
a different ontogenetic development of the ornamentation,
the ribs become thinner and bic·
concave, and the ventral tubercles disappear;
Protacanthoceras Is small and involute when
· compared to Codazziceras.
This genus is named in honor of the 19
.century geographer Agustin Codazzi.
Cogazzicergs scheibei (Riedel)
Pl. 15, fig. 1; Text-figs. BR, 88
1938 Lyelliceras scheibei Riedel, p. 55,
pl. 9, figs. 7, 8; pl. 13, fig. 17.
1954 Texanites aff. seiTatonuilf;natus (Redtenbacher),
Biirgl, p.32 [ex spec. HB-
81A. SGNMP].
1957 Texanites aff.semztomarginatus (Redtenbacher),
Burgi, p. 139.
non 1957 Lyellicems scheibei Riedel, Biirgl, pl.
10, figs. 3, 3a.
1964 Texanites aff. semztomarginatus (Redtenbacher),
Etayo-Sema, p. 127.
1964 Lyelliceras scheibei Riedel, Etayo-Serna,
p. 124.
non 1965 Lyelliceras scheibei Riedel, BUrgi, in
Campbell and Btirgl.
Holotype. The specimen described and illustra·
ted by Riedel, 1938.
Hypotype. (U.N.C.M.H.N.C.P.Hy.N.43).
Type l.ocality. Cordillera de Virginia, NW de Ia
estacion Virginia, Girardot, Cun·
dlnamarca.
A) Up to H 15 mm (C-134). The initial
four whorls are smooth ; at the beginning of the
fifth whorl, low pleats are visible, they rapidly
become prominent; they begin at the umbilical
seam and develop a thorny tubercle at the umbilical
rim, they are nearly mdlal on the flank and
develop a long clavate tubercle at the periven·
tral margin (::;line of involution); adapical to each
of these primary ribs an Intercalary rib develops,
it begins in a subdued manner near the periumbilical
tubercle but does not reach it, however,
both ribs give the appearance of fanning a V; at
first the intercostal spaces are broad and shallow
on the flank. The ribs become very prominent
on the fifth whorl, however, they are depressed
near the middle of the fik.
On the sixth whorl the inclined umbilical
wall rounds into flat parallel sides; tlie latter are
3/4 of the height of the whorl; the adventral
fourth of the whorl Is beveled and limited adventrally
by a sharp clavus; the ribs cross the
venter transversely and bear a siphonal clavus
corresponding to the periventral clavus.
B) Up to approximately 75 mm D (C-134).
The ornamentation of the early whorls is as
previously described; the livin g chamber occupies
two thirds of the last volution. At places
where the test is present the ribs appear as if
actually bifurcating in a V fashion from the periumbilical
tubercle which elongates and slants
adorally on the inclined umbilical wall.
Toward the last half of the living chamber
the tuberculation begins to attenuate, especially
the periventral clavi, and the ventral median 11·
ne of clavi disappears, leaving an arched ribbed

84
venter; the ribs become biconcave and split Ion·
gitudinally in several riblets; the angle between
the ribs decreases. .
C) Up to 96 mm D (C-134). On this speci·
men only the ornamentation of the living cham·
ber is observed ;the ribs that bifurcate from the
umbilical tubercle decrease their angle and approach
each other, furthermore, they tend to
divide into several riblets (up to three); in this
specimen the ventral median row of clavi,
though very attenuated is still recognizable.
DIAGNOSIS. This species is characterized
by: A) its large size, B) its prominent ornament
of alternating (or bifurcating) long and short
ribs, C) the arrangement of the tubercles,
spinose periumbilically, clavate ad ventrally and
ventrally, D) the biconcave ribs on the adult
and the loss of the tuberculation.
Measurements D Euw H w D/Euw D/H No.R
% %
C-134 7 ? at 15 13 7 7 16(1/2)
C·134 757 39 24 22 527 32 19(1/2)
C•134 96 5"3 34 34 56 35 40?(3/
. COMMENTS. Ritdel (op.cit., p.55) dis·
tinguished his Lyelliceras · scheibei from the
other known species of Lyelliceras by the alternation
of long and short ribs; he also compared
his species to Ammonites ospinae Karsten but
the union of the ribs at the periumbilical tubercles
and the whorl section, wider than high,
in Karsten's species were considered sufficient
to diffe rentiate both species.
I adhere to Riedel's criteria especially the
latter; Karsten's species has rounded, ball-like,
strong tubercles. Karsten's species apparently
comes from beds overlying beds that yielded
Ammonites toroanus Karsten and Ammonites
mosque rae Karsten of Lower Turonian age.
OCCURRENCE. Lower Coniacian.
·
£o dazicer fina.n. m..
PJ.t3, 1ig, l7; Text-figs. 8M, 8N, 8Q, 88.
1957 A canthoceras (?) ospinae (Karsten),
· Biirgl, p.137.
1957 Acanthoceras ospinae (Karsten), Biirgl,
·
pl.12, fig. 5a, 5b.
1964 Acanthoceras cf.ospinae (Karsten), Etayo­
Sema, p. 34.
1964 Acanthoceras ?ospinae (Karsten), Etayo­
Serna, p. 124, pars, Burgi's identification
only.
1968 · Acanthoceras ·ospinoe (Karsten), Etayo­
Sema, p.60.
1972 Acanthoceras ospinae (Karsten), Etayo
Sema, p.46.
F. ETAYO · SERNA
Holotype. C-134 (U.N.C,M.H.N.C.P.Ht. N.66)
Paratype. (C-134 (U.N.C.M.H.N.C.P. Pt. N.67)
The first whorl is smooth; the second
whorl is inflated and has a reniform section, the
third whorl has a subelliptical section: the
flanks are subparallel, slightly convex, the venter
is widely arched, the umbilical wall is abrupt
and rounds into the sides without forming a definite
rim. At the beginning of the fourth whorl
broad pleat-like ribs develop; they begin to be
well defined at the umbilical rim and on flank
form a faint adoral bow up to the adventral
third of the flank where they describe an adoral
concavity , they end at the perlventral margin at
claviform bulges. Wide constriction-like intercostal
spaces are parallel to the ribs, but unlike
the latter, they continue weakly across the venter,
forming wide adoral linguiform projections.
Contemporaneously very weak clavi develop
along the ventral median line corresponding
to the ventrolateral clavi. On the fifth whorl the
ornament is well defined: there are coarse ribs
which begin at the umbilical seam, developing a
clavate swelling at the periumbilical rim where
they bifurcate into radial branches in a Y fashion;
both branches develop a spiniform tubercle
at the beginning of the adventral third
of the flank (= level of the involution line),
from this tubercl the ribs trend obliquely
adorally on the beveled adventral third of the
whorl, they have a sharp periventral clavus and
cross venter normal to the median line where
they attenuate and develop a clavus. The
intercostal spaces are deep and as wide as the
ribs, especially those separating pairs of ribs.
On the sixth whorl the section is higher
than wide, the umbilical wall is subvertical and
short, rounding rapidly into the flank s which on
their inner three quarters of height are flat and
parallel but on the adventral quarter are trunca·
ted; on the costal whorl section the venter ap­
pears coronate , but on the intercostal section
the venter is a wide ar.
. On: tl')e seventh whorl the periumbilical
bullae are very prominent and more widely spa·
ced, contemporaneously one or two intercalary:
ribs develop: they begin as if they were elonga·
ted in a subdued manner tangent to the umbilical
rim, then they are rectiradiate on the adven-.
tral half of the flank and bear weak extemal la
teral tubercles, the periventral and ventral median
tubercles are regulary emphasized. On one
paratype (C-134) the intercalarlyribs reach the
umbilical rim and all ribs are much more promi·
nent on the venter.
DIAGNOSIS. This species is characterized
by •the ontogenetic development of its ornament,
A) with a rapid appearance of intRrcalapr .
ribs and of bifurcating ribs in a Y-like fashion,·
B) the areentuated stressing of the periumbilical
bullae with growth, and D) the relatively fine
ribbing.

86 F. ETA YO - SERNA
rent localities although presumably the same
stratigraphical level: I) a juvenile specimen of
about 120 mm diameter (as measured on figure
3, plate 8 of Schliiter's paper), and II) an adult
of about 297 mm diameter (measured on fig. 1,
pl. 8, op. cit.). These illustrations were accepted
as representig conspecific specimens by Laube
and Bruder, whose own figure of the species,
one adult specimen, shows a subrectangular section
comparable to that of Schliiter's specimen_
(op . cit., pi.S, fig. 1).
Juveniles of von Schlotheim's species, in
Schluter's (op. cit. p. 20, pl. 8, fig. 4) sense ha·
ve a high rectangular whorl section and numerous
clavi, up to 20 per whorl on the ventral
margins.
In contrast, some South American speci·
mens referred to Mammites, Cor instance that
figured by Benavides Caceres (1956, p. 468, pl.
55 , fig. 5·6) have a regular ornament with less
numerous, strong clavi on both sides of the ven·
tral median area, and also have a "subquadrate"
whorl section; thus, these South American spe·
cies of Mammites have an accelerated development
of the ornamentation with few prominent
ventral clavi, unlike the type species.
The new species from Colombia also di·
ffers from the Tunisian "Mammites nodosoides
var Afra" Pervinquiere (1907, p. 310, text-fig-.-
118, pl. 18, fig. 2, 3) which has radially elonga­
_ted periumbilical tubercles rather than conical.
Pei:'Vinquhre's species is also compressed. Pervin·
quiere's Mammites nodosoides Schlotheim,"Forme
typique" (ib ., p. 310, pl. 18, figs. 1a, b) has
very strong, less numerous periumbilical tuber·
cles which dominate in development over the
upper ventrolateral tubercles, the reverse ofthe
condition on the Colombian species. In my
opinion, Pervinquiere's specimen is not to be
referred to M. nodosoides sensu Schliiter.
OCCURRENCE. La Frontera Formation.
Lower Turonian.
Msunroites ugQ.UL !ill..
Pl. 13, fig. ; Tex-fig. 8.0.
Holotype. (U.N.C.M.H.N.C.P.Ht.N. 68).
Only the holotype is available. The first
three whorls are smooth , subcylindrical in sec·
tion; on the fourth whorl there are acute to ro· .
unded, subradial, prominent ribs separated by
shallow, wider intercostal spaces; on the fifth .
whorl a differentiation of the ribs occurs; they
begin as folds at the umbilicitl seam and describe
a concave arc on the umbilical wall ; on the flanks
some are high and acute and other are broad
and rounded; on some of them a sharp subtrian·
gular periumbilical tubercle is present; at this
stage the whorl section.),&_ subquadrangular (H:
5mm; W: 5mm); the umbilical wall is oblique
and merges into the flanks in a broadly rounded
umbilical rim, here is the maximum whorl width ,
on the adumbilical and central thirds the flanks
are parallel but they have a slight tendency to
converge toward venter; the adventral third of
the flank is beveled to slightly concave, with a
tubercle at each margin; the ventral median zo·
ne is shallow and concave ; the intercostal whorl
section is subcylindrical.
On the sixth whorl the ornamentation
changes drastically : no umbilical tubercles, the
ribs become acute folds or accentuated bundles
of growth striae; they describe a shallow, short
adoral concavity on the umbilical wall, then
they form a broad arc on the adumbilical and
central thirds of the flank, then on the adventral
third they form an oblique, crescentic concavity
and extend onto the venter in attenuated form
where they make an adoral arc on the ventral
median zone ; on the periventral margin of the
venter the ribs have a bullate tubercle which Ia·
ter becomes rounded, and on both sides of the
ventral median zone they develop thorny, outwardly
inclined clavi.
On the adoral half of the last whorl, the
ribs become riblets that bifurcate near the mid·
die of the flank forming a Y, with one branch
bend adapically and the other ad orally , so every
periventral tubercle is connected by secondary
riblets from two different primary ribs, forming
a zig-zag pattern; at this stage the whorl section
is subquadrangular with its maximum width at
the umbilical rim, the venter is marrow, concave.
The growth striae follow the course of the ribs.
DIAGNOSIS. This species is characterized
by its strong ontogenetic changes: A) it is first
smooth and has subcylindrical whorl section, B)
next it becomes trituberculate with strong ribs
(Mammites-Iike stage), C) it becomes bituberculate,
gains a subquadrate, adumbilically bulging
whorl section and develops zig-zag like fine rib·
bing.
Meuurementa D Euw H W D{Euw D/H
% %
c. 263 31 11 13 16 36 41
The measurements are taken where the
preservation (?f the conch permits them.
. COMMENTS. This species is provisionally
referred to Mammites because of the transient
stage du.ring which it resembles .Mammites; no
indication of constrictions were observed. The
only species known to me that resembles M. fu·
gax, has been referred to Be '\ ueites by Reyment
(Benueites spinosus Reyment, l954a, p.156, pl.
3, fig. 2; and' especially 1955, p. 58, pl.13, figs.
24 , and text-fig. 25a), but in this species the
perillmbilic;al.tubercles develop only late during
growth, contrary to the situation in M. fugax.
Incidentally, Reyment subsequently figured
Benueites sp inosus as coming from Colom·
_ bia (La. Frontera, Alban; 1971, pl. 12, figs. 2a·b,
pl. 3, fig. 3a, 36 ).
In summary, in B. spinosus the ontogenetic
change in ornament is from finely costate to

ZON ATION O F THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 87
strongly costate and umbilically tuberculate,
the opposite is true in Mammites fugax n. sp.
OCCURRENCE. La Frontera Formation.
Lower Turonian.
mmi!fUQLt:ulatJ!LU· sp.
: 13;ii 10; Text-fig. 8P.
Holotype. C-310 (U.N.C.M.H.N.C.P.Ht.N.69).
Only the holotype is available. The penultimate
whorl is of relatively moderate size , its
adapical segment is smooth except for channellike
oblique constrictions preceded adapically
by a rounded flange that bears a prominent
rounded UIJlbilical tubercles; the space between
two constrictions is polygonal, reniform.
At a point, and more or less suddenly, paralleling
both sides of the ventral median region,
11. pair of clavi arise on ven ter. The ribs issue
from the umbilical rim and extend radially to
about middle of the flank where a conical-like
tubercle occurs; from it the ribs trend slightly
prorsiradiate.
On the last preserved segment the section
is lozenge-shaped with maximum width at the
umbilical rim; there are single primary ribs
which arise from a bullate umbilical tubercle,
they trend rad ially up to the lateral tubercle
which is adventral to middle of the flank, from
this tu bercle the rib slants adorally and develops
another weak, round and feebly clavate tubercle
at the periventral margin, and then the rib
goes straight across the venter. Between two primary
ribs with periumbilical tubercles there
may be an intercalary rib ·that disappears near
the umbilical rim ; sporadicallytwo ribs seem to
arise from an umbilical tubercle . At this late stage
the whorl section is lozenge-shaped: the ven·
ter is flat, the flanks diverge to the periumbili·
cal tubercle and then they slant to the umbilical
seam fonnin,g an oblique umbilical wall.
A smaller specimen with the same rib de·
velopment and conspicuous "juvenile constric·
tions" on the inner whorls is referred to the
same species. On both specimens the areas with
test preserved are covered with fine growth
striae crossed by strigations.
DIAGNOSIS. This species is characterized
by: A) the development of a lozenge-shaped
whorl section in the adult, B) the bullae-like
umbilical tubercles from which usually only
one rib is issued, C) the non attenuation of the
ribs on the venter.
Mea.urementa D Euw H W D/Euw D/H No.R.
, C-310 (Paratype) 20 9
C·310 (Holotype) ? ?
8 9
? 7
% %
45 40 18
? ? ?
COMMENT.S. The whorl section of the
ault of this species is very peculiar and no si·
,lndar shape is known to me. Mammites revelie-
rianum Coustillier, after the whorl section lllustrated
by Karrenberg (1935, p. 132) has a rather
pyriform to quadrangular section.
OCCURRENCE. La Frontera Formation.
Lower Turonian. _
· -·
· .. ,.'..,; .
Family VASCOCERATIDAE
Genus [F@scifs;. g.] = 4/c<
TYPE EPECIES. Ammonites toroanus Karsten,
1858, p. 109, pl. 4, fig. 2.
DIAGNOSIS. Conch of moderate size,
craterumbilicate to angustiumbilicate; the
whorl section is subcircular on the innermost
whorls, but it progressively becomes highly
convex or flattened ogival.
The constrictions are bisected by a
prominent rounded rib which extends adorally
on ven ter in a short lingu ifonn arc; the edges of
the constrictions are thickened and rounded as ·
if they were ribs; minor constrictions and rib lets
may develop parallel to the principal ones, but
usually the ornament between constrictions is
dominated by growth striae; the most prom!·
nent observable ornament is internal, well impressed
on the internal molds.
The suture has bush · like E/L,
and subsymmetrical , deep, trifid L.
COMMENTS. This genus differs from
Thomasites Pervinquiere (1907), which has urn·
bilical and periventral tubercles; from Neop tychites
Kossmat (1895) which has an evenly arched
whorl section, a constricted aperture and
by the absence of constriction-rib type of internal
ornament.
frgncir;:oft.g§ §.U arezi n. sP.o;
Pl 13, fig. 2; Text-figs. SX, SY, 8 ii.
Holotype . C-310 (U.N.C.M.H.N.C.P. Ht. N.70)
Paratype. C-310 (U.N.C.M.H.N.C.P. Pt. N.69)
A) Up to 6 mm D (C-310). Several speci·
mens ·were dissected but the protoconch was
not observed. The smallest specimen studied
has a moderately globose shell, the whorl section
is circular to suboblong; the umbilical wall
is subvertical and rounds evenly into the convex
sides, the venter is arched. The surface of the
shell is apprently smooth.
The adapical third of the whorl shows a
ridge-like prominence across the venter and
dying about near middle of the flank; this is
interpreted as fortuituous; ad apical to the ridge
and paralleling it there is a narrow shallow sulcus;
several constrictions without adjacent rid·
ges divide the conch into segments.
B) Up to 10 mm D (C-'3 10). At this dia·
meter the whorl section becomes compressed,
the sides are subparallel and the venter Is arched;
the umbilical wall is vertical and the umbilical
rirr: is abruptly rounded.

88
The adapical end of this conch has a
prominent rounded rib which starts near the
middle of the flank and prqects adorally as a
linguifonn arc on venter; adapical to this rib
there is a very weak parallel sulcus, adoral to lt
there is a parallel channel - like constriction.
At the end of the first fourth of the
whorl there is a similar more prominent roun·
ded rib with its adjacent constrictions.
Between the second and third fourths
of the whorl there is a similar constriction, but
it is preceded adapically by a ridge-like swelling
on the test; the third fourth of the whorl is like·
wise ended by a prominent rounded rib but
no ridge develops, however, the adapical cons·
triction is more accentuated and wider than the
adoral constriction which in addition has a well
marked, thin, rounded rib just adorally.
The fragments of test on the last fifth of
the whorl show that the growth lines describe
a feeble and adumbilical concavity and a slight
arc on most of the flank to finally project ado·
rally on the venter like the constriction. There
are five pairs of ribs and constrictions per whorl.
Between the constrictions the test is smooth
except for the growth lines; the space between
the first four constrictions is equal, the fifth
one has half the previous distance.
C) Up to 20 mm D (C-310). Specimen sli·
ghtly compressed. The whorl section has flatte·
ned flanks, the venter tends to be acutely ar·
che d.
The whorl is divided by six prominent
rounded ribs, with a constriction on each side,
of which the adapical one is wide and shallow
whereas the. adoral one is narrow and deep,
both constrictions coverge and merge at the
umbilical margin where _a channel-like depres·
sion is formed, the rib disappears at the adum·
bilical third of the flank; both the adoral and
adapical constrictions are bordered by rounded
riblets distinct only on the adventral half of
the flank; the intercostal space is covered by
owth striae only; the spacing between the ribs
1s irregular but there are only six principal ribs
per whorl; a minor pair of constrictions separa·
ted by an acute riblet is visible adoral to each
principal rib.
Viewing the whorl from the adapical end
the segments appear to be bulgirig laterally. In
one paratype (C-310) there are several of these
·
acute riblets.
D) Up to 25 mm D (C-310). The whorl
section has slightly convex sides and an arched
venter; the width of the main ribs is greater ada·
perturally, but in other respects it has the same
appearance as the previous whorl.
The living chamber occupies the last third
of the whorl. Where the test is preserved the
principal ribs are paralleled by the fine, attenuated
low and rib-like rounded margins of the ad·
F. ETA YO - SERNA
jacent constrictions; the groups of fine acute ribs
in all cases are developed next to the principal
ribs.
DIAGNOSIS. This species is characterized
by the ontogenetic development with : A) chan·
ge in the whorl section from subcircular to ogi·
val with subparallel flanks, B) the rounded pri·
mary ribs accompanied by constrictions that
first appear on the ventral region and then advance
toward the umbilical region during growth
C) its narrow umbilicus.
Meuurementa D Euw H w D/Euw% D/H%
"C-310 6 1 3 3 17 l\0
C·310 10 2 5 4 20 l\0
C·310 20 3 10 8 15 60
C·310 26 3 13 11 12 62
COMMENTS. The type species Ammoni·
tes toroanus Karsten, from Venezuela (Karsten,
1858, p, 109, pl.4, fig. 2a, 2b) is a thicker
species apparently with a larger umbilicus
tnowever, KaJ:Sten's original have the umbilicus
filled with matrix; see his pl.4, fig.2a), and most
importantly the internal ribs are stronj!er and its
venter wider than in Franciscoites suarezi.
Leanza (1968, p. 192) compared "A mmonites
toroanus'' Karsten to the inner whorls of
his "Lewesiceras ubatense ", because of the pre·
sence of scattered constrictions; in my view the
similarity dee; not indicate affinities.
OCCURRENCE. La Frontera Fonnation.
Lower turonian.
Genus j Imlayiceras 1 Le z3 1
1968.
= W,..·,f,w Cw

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMIA BY AMMONITES 89
tion of the shell becomes accentuated, at the same
time the strength of the ribs decreases even
though their sinuosity persists; when the test is
preserved the ribs are indicated by slightly rai·
sed bundles of growth. striae; the adapical slope
pf these.!>undles is steeper than the 1 a.dqral slope;
the intercostal spaces are vai'}able m width but,
usually wider than the ribs. Ad orally the ventral
sulcus gets weaker.
C) Up to over 35 mm D (C-310). The
whorl section is slightly wider toward the cen·
ter of the whorl; the low, weak ribs arise at the
umbilical edge In couples and are very weak
when they cross the venter; the· periventral
carinae have almost disappeared and the venter is
flat and truncate. The apertural margin is plain,
it follows the falcoid path of the ribs. The living
chamber is about two thirds of the last whorl.
DIAGNOSIS. This species is characterized
,by: A) a juvenile early stage with bicarinate and
sulcate venter, together with prominent falcoid
ribbing; B) a later stage with flat venter and numerous
weak, flattened falcoid ribs that arise in
bundles at the umbilical rim and split in twos
on the external third of the flank and cross the
venter producing crenulated edges; C) a narrow
umbilicus throughout the ontogeny.
MeaJURmenu
C-310
C·310
D Euw
25 3
35 4
H W D/Euw% D/H %
14 7 12 36
20 11 11 57
COMMENTS. Imlayiceras was proposed
by A.F. Leanza (1968, p.l96), and considered
different from Hoplitoides von Koenen (1898)
"restringido al gropo de H. /atesellatus von Koenen"
(op.cit., p. 198), largely because of the
presence of shallow but evident constrictions in
the juvenile stage
The early juvenile stage of I. ralphimlayi
at fm t glance resembles that of lmlayiceras
washboumei Leanza, (1968, pl. 4, fig. 3-4) but
the Colombian specimens do not show constric·
tions although the intercostal spaces are slightly
accentuated (not interpreted as constrictions
here); the juveniles also have a narrow umbilicus
and, although Leanza remarks that his
illustrated juvenile (see op. cit., pl.4, fig.3) has a
proportionately wide umbilicus, I suspect that
this width is an optical effect due to the umbilicus
being filled with matrix on Leanza's specimen
(see op. cit., pl.4, fig.7).
. The largest specimen in my collection also
resembles another specimen [Paratype USNM
132559] refened by Leanza (op. cit., pl.6, figs.
4 ,5) to his species, bu t• he describes the orna·
mentation of his species as consisting only of
fine growth striae, whereas on the Colombian
species the striae are in elevated bands and an
incons}:)icuous ribbing is present on the intemal
mold. Furthermore, on the Colombian species,
the ribs cross the venter and produce a railroad
aspect with Irregular crenulated edges. At this
stage the carinae are still prominent in Leanza's
species but on I. ralphimlayi the venter is already
truncated and the whorl section is evenly
•
.:II: ··
arched although slightly truncated on the ad·
ventral fourth of the flanks.
The whorl section of the Colombian
species . resembles that of "Hoplitoides munieri
., Pervinquiere (107, .p.2.1;7·•·PllD . ·•- la, b,
2a, 2b), but the latter was descnbed as havmg
"Fiancs lisses (ni cotes, ni tubercules) , reguliere­
ment mais tres faiblement bombes '. Leanza
suggested that this species could also be included
in his genus.
In the Mexican Hoplitoides cf • . H. munieri
figured by Kummel and Decker (1954, p.317,
pl.33, fig. 1,2, Text-fig.7 ,10) they indicate that,
"Low, indistinct, irrelarly spaced transverse
ribs cross the venter' ; the Mexican species is
noticeably similar in general shape to my specimens
except that it is larger and has a more persistenUy
excavated venter; the latter species also
was indicated by Leanza as possible member
of Imlayiceras. The internal whorls of Hoplitoides
inca Benavides Caceres (1956, p. 475, pl.63,
figs. 6-11), are also similar but on the Peruvian
species the ventrolateral ridges persist longer in
the ontogeny.
OCCURRENCE. La Frontera Formation.
Lower Turonian.
This species is named in honor of Dr.
Ralph Imlay of the U.S. Geological Survey.
Genus §esiaJ Pervinquiere, 1907.
Fagesia Pervinquiere, 1907, p.319.
TYPE SPECIES. Olcostephanus superstes Koss·
mat, original designation.
Fa za.LJi.Jl .sp.
1it13 , fi'g. l; P1.14. fig.5;
Text-fig. ST.
1957 Vascoceras sp. nov., BUrgi, pl.13, figs. Sa,
8b.
Holotype. C-310 (U.N.C.M.H.N.C.P. Ht. N.72)
Paratype. C-310 (U.N.C.M.H.N.C.P.Pt. N.71)
A) Up to 17 mm D (C-310). The inner
whorls were dissected in two specimens, but the
protoconch was not reached. They have a reniform
whorl section: depressed with the flanks
and the venter formng a wide arc,"the umbili·
cal wall is vertical. The umbilical rim is abrupt
but not acute.
Externally the conch has periodically wellspaced
flanges that begin at the umbilical rim
with a bullae or knob-like swelling and trend
toward the venter with a slight adoral concavity
on ·the flanks; they project forward on the
venter forming an acute arc. Adapical to this
ridge there is a wide shallow constriction that
reaches the umbilical rim; adoral to the ridge
there is another constriction which however, is
narrower than the preceding one and which is
paralleled adorally by a moderate ridge which

90 F. ETAYO · SERNA
dies out near the middle of the flank. This
second ridge is only recognizable when the test
is preserved.
Midway between two principal flanges
there is a bullae-fonn swelling; this swelling
dies near the middle of the flank. The ornament
becomes. prominent almost suddenly;
the two ridges arise from a prominent conical
periumbilical tubercle and the interposed bullae
becomes at first the start of one rib, then of two.
All the ribs tend to be of equal strength.
B) Up to 33 mm D (C-310). The ornament
continues in the same pattern but the tubercles
corresponding to the original intercalary ribs
are the most prominent; inte:rspersed intercalary
ribs which die near the middle of the flank
may occur; the section becomes wide and has a
very high umbilical wall.
C) Up to 46 mm D (C-310). The living
chamber occupies about halt the last whorl; the
intercostal spaces as in the preceding stage are
about twice as wide as the ribs.
DIAGNOSIS. This species is characterized
by: A) its rounded subrectangular whorl section
in the adult, B) the increasing strength of its
ribs and the periumbilical mammillate tubercles.
Measurements D Euw H w DfEuw D{H
% a/o
C·310 17 6 7 11 35 41
C-3 10 33 11 14 22 33 42
C-310 46 ?
COMMENTS. Fagesia zanellai differs from
''Fagesi peroni var. colombiana" Fritzche (1923),
because the latter is smooth and flattened. Fagesia
thevestensis (Peron) (1896; p.23, pl.7,
figs. 2-3; Pervinquiere, 1907, p.325, pl.20, figs.
5a,b; 6a,b), is a similar species but it possesses
from 14 to 15 periumbilical tubercles whereas
in the. ,Colombian species the tubercles vary
fromJfto 10; further, the intercostal spaces are
wider'iand the conch is more involute at comparable'dlameters
in the Colombian species.
OCCURRENCE. La Frontera Fomiation.
Lower Turonian.
This species is named in honor of the geologist
Livio Zanella.
_
Genus (P _ _ _
a a71U!mmit
"""
s Furon, 1935.
- · \". ·
Pa
ramammites Furon 1935, p. 58;.
__
n
__
TYPE SPECIES. Vascoceras polymorphum Pervinquiere,
subsequent desig·
. ttation, R1!yitulnt 1954, foot·
- note p. 255. · .
.f.aron.!.ammies_..£2!o_ mbian!:f!.
n.sp. . .
Pl. 13, figs. 5, 13.
1968 Paroi7Uitnmites cf.P. gracilis (Pervinquiere),
Etayo-Sema, p. 43, fig. 13, T. 1.
1972 Paromammites sp. Etayo-Serna, p. 47.
Holotype. L.Vs-7 (U.N.C.M.H.N.C.P.Ht.N.73).
Only the holotype is available; the internal
whorls are not observable. The whorl section
is depressed, coronate; the conch is widely umbilicated.
The ornament consists of flaring, com·
pressed triangular peg-like umbilical clavi that
begin at the umbilical seam; from these clavi
usually two but sometimes three ribs branch;
the ribs are compressed and acute and cross the
flank radially or with a feeble adoral concavity,
they bear a minute, almost imperceptible angulosity
(or tubercle?) near the middle of the flank
and they have an acute bullate tubercle which
is slightly bent adapically on each side of a
narrow median ventral area; along the median
ventral line the ribs are very weak_, almost interrupted
but have a weak adoral arc. There are
16 periumbilical tubercles per whorl; the intercostal
spaces are one and a half times as wide as
the ribs on the internal mold,they are subequal
on the test.
Toward the adapical half of the last whorl
there are deep oblique constrictions across the
flanks, they parallel the ribs and begin at the
umbilical seam. When the test is preserved, stri·
gations are observed on it.
DIAGNOSIS. This species is characterized
by: A) its wide umbilicus with vertical wall surrounded
by stake-like tubercles, B) its reniform
whorl section, and C) the very subdued tubercles
on the middle of the flanks.
Measurements D Euw H W DfEuw D/H
. % %
L.Vz.· 7 25 12 9 13 48 36
COMMENTS. Paramammites colombianus
differs form Paramammites gracilis (Pervinqui·
ere) [1907, p. 337, pl. 21, fig. 41, the species I
previously compared it with, by lhe more com·
pressed whorl section and strong tubercles near
the middle of the flank of the Tunisian species.
The ribs are more numerous in the Colombian
form:, 16 per h8lf whorl compared to 11 in the
Tunisi.lu\ species. The specimen described from
Vene;uela by Leza (1968, p.200, pl. 1 ! fig .. !-
4) as "Paramamm1tes polymorphus Pervmqm­
re", has a more compressed whorl section and
has stt;ng, blunt ribs and tuberculation.
·
occuRRENCE.
San Rafael Formation. · ·
LowefTuronian.
Family COILOPOCERATIDAE ;· .
G,enus •·
[8 oplitoides)vo n Koenen:l·;
. ... , . .
Hoplitoides von Koenen, 1898, p. 53. ::;:- >:·
YP
T
E SPECIES. ffoplitoides latesellatus v'on·
Koenen, original designatjR,n,
. ;
Hop1itoides b,e.!!!,!Znm ojc •
n. sp.
Pl. 13, figs. 4, 8.

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBiA BY AMMONITES 91
1972 Hoplitoides ingens (v.Koenen), Reyment,
p. 915, pl. 35, fig. 4a, 4b, 4c.
Holotype. C-310 (U.N.C.M.H.N.C.P.Ht.N.74).
paratype. C-310 (U.N.C.M.H.N.C.P.Pt.N.72) •
.. • \1 ,,1 .... . -· .
The innennost whorl observed on internal
mold is the thiid; the whorl section is subcircular
at the ad apical portion, It has a slightly flat·
tened venter, the flanks are evenly conve, the
umbilical wall is short an!i vertical; the tourth
whorl has a noticeable increase in height, it beco·
mes vaulted with weakly conve sides; a sharply
beveled area connects the lateral carinae to the
flanks; this produces a narrow, deeply grooved
venter. The fifth whorl increases notably in
height and becomes lanceolate In section with
the ventral grQPve preserved.
In this particular specimen the siphon does
not run beneath the center of the ventral groove
but instead under one of the carinae (diagenetic
effect?). The only ornament discernible is low,
sinuous ribs that are visible only with oblique
illumination; on the adventral third of the flank
they are crescentic and they fade out at the edge
of the periventral carinae. A larger fragment
(paratype, C·310) shows the change from a te·
nuously sulcate to a rounded venter.
The suture line has a wide, asymmetrically
bifid E/L saddle, it is very high and descendent
into the wide L lobe; L/U saddle is subrectangular.
DIAGNOSIS. This species is characterized
by: A) the rapid change in shape of the ventral
region from bicarinate to narrowly rounded, B)
its low sinuous ribs, C) the asymmetrical, descen·
dent E/L saddle and the wider, shallow and tri·
fid L.
Me811Urementl D Euw H W D{Euw D/H
% %
C-310 34 3 20 10 9 61
COMMENTS. Reyment (1972, pl. 35, fig.
4a, 4b, 4c) figured this species under the name
Hoplitoides ingens (v. Koenen) I actual diameter
of Reyment's S f. ecimen about Omm.] however,
using Reyment s description of von Koenen's
species one observes: A) the internal mold of
Hoplitoides ingens as illustrated by Reyment
(1955, pl. 20, figs. la, lb) from Nigeria shows a
lanceolate venter; at an equivalent diameter H.
hemanmojicae shows instead a wide sulcate
venter that just begins to round (see Reyment,
1972, pl. 35, fig. 4c), B) none of the suture
lines illustrated by Reyment of different
"subspecies" of Hoplitoides (1955, partim)
have a E/L saddle well bisected and subsymmetrically
bifid or an elongated steplike arrangement
ot the accessory elements causing a strong
descendent flexion of the uture line and the
consequent asymmetry of L; for example,
compare the ontogeny of the suture line of
H. hemanmoiicae (="H. ingens ") in Reyment
(1972, pl. 35, fig. 4b) with that of Hoplitoides
rngens (von Koenen) in Reyment (1955, pl. 18,
fig, 4).
OCCURRENCE. La Frontera Fonnation.
Lower Turonian.
This species named in honor of the geologist
Heman . Mojica R. .. , · .
Hoitoides lacabJJJmoo n. sp.
PI. 3, bg. 9. - -- -.
' .
--- -
?1972 Hoplitoides ingens laeuis [Solger], Reyment,
p. 915, pl. 35, fig. 6.
Holotype. (U.N.C.M.H.N.C.P.Ht.N. 75).
The conch is discoidal, involute; the whorl
section is slightly inflated on its central and ad·
umbilical thiid, but compressed to rather excavated
on the adventral third. The venter is narrow,
concave, boidered by two acute carinae.
The ornament consist of fine raised striae
whicti begin at the umbilical margin where they
describe a slight concavity, they then trend prorsiradiate
up to the adventral third of the flank
where they describe a crescentic concavity,
then the y extend onto venter, crossing it in a
slight adoral arc. Short, sickle-like swellings,
slightly oblique to the crescentic trend of the
growth striae , appear on the adventral third of
the flank; the distance between the swellings
changes but it is always more than three times
the width of the swellings.
DIAGNOSIS. This species is characterized
by: A) its disk-like shape and grooved ventral
zone, B) the bundles of falcoid growth striae on
the adventral third of the flank are crossed
obliquely by claw-like swellings, C) the absence
of any periumbilical swellings.
Measurement D Euw H W D/Euw"/o D/H%
La Frontera 48 4 29 ? 8 60
COMMENTS. A species that resembles
the H. lacabagnae is figured by Peron (1896, p.
40, pl.l, fig.6,7) as "Discoceras cf. largilliertianus
d'Orb." from Algeria; his species is more
inflated on the central and adumbilical thirds of
the whorl than the Colombian species, and its
venter widens quickly adorally (as observed on
his figure), but this occurs slowly in the Colombian
species.
Reyment (1972, pl.35, fig.6) illustrated,
but did not describe, an apparently closely related
species from Colombia; he wrote (ib. p.915)
on the caption to figure 6 of plate 35, "individu
du type H. ingens laevis, c'est-a-dire des formes
sans acune ornamentation veritable"; the speci·
men illustrated by Reyment, however, has fine
but very well defined falcate riblets on the internal
mold but in the Nigerian species descri·
bed by Reyment (1955, p1.18, fig.2) one observes
puckers or folds; furthermore, on the Co·
lombian specimen figured by Reyment (op. cit.,
p1.35, fig.6), there are crescentic sweUings
which cross the trend of the growth striae on
the adventral third of the flank and especially
on the last third of the length of the last wliorl,
but this trait is not noted by Reyment in his
discussion.

92
OCCURRENCE. La Frontera Fonnation.
Lower Turonian.
JLf!itoides lgc,iraldae n. SE·
Pl:-3, 1fg."f.t&· - " -
Holotype. C-264 (U.N.C.M.H.N.C.P. Ht.N.76)
The conch is discoidal, narro . wly umbili·
cated; the whorl section ·is lanceolate; the umbi·
lical · wall is vertical and rounds abruptly into
the flanks which are evenly convex on the
adumbilical and adventral thirds of the flank
but slightly concave to compressed on the adven·
tral third. The venter is narrow, pulley like, for·
ming an open V, paralleled on both margins by
an acute carina.
The ornament consists of seven bullae·li·
ke periumbilical swellings from which two bun·
dles of riblets diverge, each branch is slightly arcuate;
on the adumbilical third of the flank
each of these bundles form crescentic swellings
which fade out before reaching the ventral carl·
nae. One or two intercalary swellings occur be·
tween each couple of bifurcating ribs.
DIAGNOSIS. This species is characterized
by: A) its V like venter, B) the periumbilical
swellings from which bundles of riblets are
issued, C) its claw -like swellings on the in·
temal half of the adventral third of the whorl
side.
Measurements D Euw H W D{Euw "k DJH0/o
C-264 50 5 28 12 10 56
COMMENTS. This species differs from H.
lacabagnae _by the absence of periumbilical swellings
on the latter.
OCCURRENCE. La Frontera Formation.
Lower Turonian.
· :}ifop"litoides (?) sp. ind.
Pl.13, fig.15.
Reference specimen. C-310.'
Only half of a compressed specimen. The
whorl section on one side is compressed and
moderately shouldered; there is a keel along the
median ventral line; the ornament is characterized
by ribs issued in pairs in a subdued manner
from the umbilical rim; they are rounded, prominent
and are radial or moderately sinuous on
the flank ending in a triangular prominence at
the ventral shoulder, these prominences are
slightly elongated in the spiral direction; between
two of the rib couples there are two (or three?)
intercalary ribs which begin approximately near
the middle of the flank and end in rounded bu·
llate prominences at the ventral shoulder.
The intercostal distances between the
primary ribs is twice the width of the ribs; the
&pace between the intercalary ribs is subequal
to the ribs. ·
COMMENTS. There is some resemblance
F. ETA YO · SERNA
between this specimen and Hoplitoides latese-
1/atus von Kenen as figured by von Koenen
(1898, p1.6, fig.3a, b, only), but the ventral region
of the latter is tabulate and there are periumbical
bullae, contrary to the Colombian specimen
which is not bullate at the umbical rim
and has a median ventral keel.
OCCURRENCE. La Frontera. Lower Turonian.
{. Family COLLIGNONICEltATIDl\El /,
2!12!!! . 0 -Wioceras J:llB,:SJ,* J4.
Niceforoceras Basse, 1948, p.694.
TYPE SPECIES. Niceforoceras columbianus
Basse, original designation.
.Jl.iceforocW!§_ boy..,g&aeJse.. n.
sp. 'Pf.14, fig.7.
Holotype. NRC-9 (U.N:C.M.H.N.C.Pllt.N.77)
The conch is involute, discoidal. On the
adapical segment of the last whorl the whorl
section is ridged, carinate, and has subparallel,
feebly convex sides, The ornament consists of
strong biconcave growth lines which begin at
the umbilical rim without any indication of tuberculation;
they extend onto venter and join
the ventral median keel in an acute V that
points adorally; bundles of these lirae form
inconspicuous flat bands arranged in an imbricating
manner.
Periventrally there are tubercles, they are
oblique, claw shaped at the adapical part of the
last whorl but they tend to become parallel to
the median plane on the adoral segment of the
last whorl.
DIAGNOSIS. This species is characterized
· by: A) its smooth appearance, B)its low, ban
ded ribbing, C) the change in trend of the
periventral tubercles from oblique to parallel
l
late in the ontogeny.
Measurements D Euw H W D/Euw% D/H04
NRC-9- 50 5 29 15 10 58
COMMENTS. This species resembles N.
umbulaziforme Basse (1948, p.695, pl.25, figs.
4a, 4b, only), but on the latter species the ribs
are more prominently raised, almost acute, and
there are weak periumbilical tubercles; N. boyacaense
is also more inflated adapically than Basse's
species . .
OCCURRENCE. Cucaita Member. Lowe1
Coniacian.
_g..;,. nu s,. ... ..!fero ( c eriJ .C!! , 9.,rossouv,
i§§t -
---···
Peroniceras de Grossouvre, 1894, p.93.

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 93
TYPE SPECIES. Pe roniceras Moure ti de Gros·
souvre, 1894, original designation.
1968 Peroniceras mouretii [de Grossouvre],
Etayo-Serna, Tab.l.
1972 Peroniceras mouretii de Grossouvre, Etayo-Serna,
p. 48.
Holotype. VL6·Cu-5 (U.N.C.M.H.N.C.P. Ht .N.
78).
Only the holotype is available. The antepenultimate
whorl has a ogival section (HW: 10;
W: 6mm it is ventrally keeled and bears two
asymmetrical shallow grooves paralleling the
ventral median carina; the flanks have fine,
rounded sinuous riblets or ribs, separated from
each other by intercostal spaces twice as wide
as the ribs; the test is thick.
The penultimate whorl has a nearly quadrangular
section: the umbilical wall is subvertical
and rounds smoothly into the convex si·
des; the venter has three carinae separated by
shallow furrows; the space between the ventrolateral
carinae and the periventral margins is
sharply truncated to excavated; on the flanks
there are prominent bar-like prorsiradiate ribs
which are feebly curved across the flanks; along
one third of the last whorl there are 14 riblets.
The ribs are issued at brink of the umbilical
wall where they develop a weak bullate swelling; .
along the periventral margin the ribs have
outwardly extended clavi.
From the periventral clavi the ribs extend
toward the ventrolateral keel and disappear
near it. The intercostal space is greater than
the width of the ribs, and increases adorally.
The last whorl has a subrctangular section. The
ribs are very prominent, rounded and separated
by channel like intercostal spaces twice as wide
as the ribs, the connection with the ventrolateral
keels has almost vanished and the periventral
clavi dominate over the periumbilical
bullae. The ventral carinae are conspicuous,
well raised and faintly undulated.
The suture line has a deep L lobe which
widens adapically but is constricted adorally by
E/L and L/U saddles.
DIAGNOSIS. This species is characterized
by the rapid change of its whorl section from
ogival to quadrate to subrectangular, B) the development
of rounded, well separated ribs on
which the periventral clavi become prominent.
COMMENTS. In ontogenetic development
of the whorl section this species is similar to
"Schloenbachia Dravidica Kossmat" (1895, p.
190, pl.23, figs. 3a·d) in which the ribs on the
young are close to each other and the venter is
narrow, with only one distinct keel and the v.!;t·
trolateral keels only suggested, the change to
subquadrate whorl follows rapidly; the specimen
described by Kossmat has been re-studied
by Matsumoto who confirmed the on_togenetic
development (1965, II, p.213) and stresses the
"Gauthiericeras-like character'' of the early
whorls.
Kossmat's species, however, has an early
ontogenetic bifurcation of the ribs from the
umbilical tubercles, wherea the Colombian species
has only single, regularly spaced ribs; in this
characteristic the Colombian species resembles
"Peronicer(ZS subtrica rjn atum d'Orbigny var.
tridol'S4tum Schlii ter;'as figured by de Grossouvre
(1894, p.94, pl.lO, fig.3); although it is
difficult to compare it to the large French specimen,
however, on the latter the ribs seem to
be persistently concave adorally whereas on the
Colombian specimen the ribs tend to be straightened
and separated; on the specimen referred
to Schliiter's species by Grossouvre (1894, pl.ll,
figs. 1a, 1b) the ribs are very acute on the umbi·
lical rim and the periumbilical tubercles acute
and far from the umbilical rim whereas on the
Colombian species the ribs are bar-like with al·
most uniform width across the flanks.
Furthermore, if Grossouvre's assignment
of the specimen on his plate 11, fig.2 to Schlti·
ter's species is correct that species would have an
ontogenetic development with a very early occurrence
of strong ribbing, the opposite of that
of the Colombian species.
OCCURRENCE. Cucaita Member. Lower
Coniacian.
This species is named in honor of the geologist
Roberto Garcia S.
Pero niceras diabloi n. s.
-· -'Pm, fig. 1; Tex1-figs. 1;·'9F;· 9a: ·
1968 Peroniceras aff. rousseauxi Gross., Etayo­
Sema, p.45, fig.13, Tab.l.
Holotype. NRC-3 (1965) (U.N.C.M.H.N.C.P.Ht.
N.79).
Only one specimen is available. The penultimate
whorl has a very indistinct ornamentation
of widely separated low ribs; on the folio·
wing whorl the ornamentation is rapidly strengthened;
the ribs start at the periumbilical margin
with a rounded tubercle, sporadically bullate,
on the flank they describe a well defined
adoral concavity, ending in compressed periventral
clavi; the ribs do not show a distinct connection
to the ventral carinae. The ribs are flat,
low and depressed on middle of the flank.
The section of the last whorl is rounded
subrectangular slightly higher than wide; the
umbilical wall is subvertical, it rounds smoothly
into the flattened sides; the space between the
ventrolateral carinae and the periventral margins
is slightly excavated to beveled, the median
ventral line is raised, and on each side of it the-

94
re is an asymmetrical sulcus bordered by a continuous
low carina. There are 15 ribs on two
thirds of the last whorl. The suture has a L
pouch·like, digitated, U3 is very oblique adumbilically
, narrow.
DIAGNOSIS. This species is characteri·
zed by : A) the rapid strengthening of its ribbing
and the dominance of the tubercles over the
ribs and the attenuation of the ribs on the middle
of the flank, B) the conspicuous suture line
with extremely oblique U3.
Measurements D Euw H W D/Euw DIH
NR.C·3(1965) 52 26 16 16 48 °k 30%
COMMENTS. This specimen resembles
those described and illustrated by Burckhardt
(1919, p.113; 1921, pl.29, fig.7-10) as "Peroniceros
cf. tricarinatum Schtilter sp. non auct.";
they are similar in the flattening of the ribs on
middle of the flanks and in the arcuate nature
of the ribs, but the Mexican species has a coarser
ornamentation earlier in the ontogeny than
in the Colombian species.
Peroniceras diabloi n. sp. also resembles
Peroniceros westfallicum as illustrated by de
Grossouvre (1894, p.98, p1.12, fig. 1) but in the
French species· the periumbilical tubercles are
clearly bullate whereas in the Colombian
species they are dominantly mammillate.
OCCURRENCE. Cucaita Member. Lower
Coniacian.
.... 1,.
,l'erv,niceruerrai o, sp..
-··- "PJ.14; fig. ;Text-fig. 91, 9J.
Holotype. NRC·Est.9 (U.N.C.M.H.N.C.P. Ht.N.
80).
Two fragments are av ailable. The smallest .
one has a rectangular whorl section and although
the specimen has been slightly compressed, the
ventral median carina is elevated, continuous
but widely undulated; it is paralleled by a lower
but continuous carina on each side; the carinae
are separated by a shallow, very asymmetrical
sulcus. The ribs are strong, prorsiradiate to fee­
hi y concave ad orally, rounded· they start at the
umbilical rim without develping a tubercle
though a.slight bulging is insinuated, they end
periventrally at strong clavate to slightly obli­
que rounded tubercles; the intercostal spaces
are slightly wider than the ribs on the internal
mold.
Sporadically an intercalary rib, that ap­
pears near middle of the flank or branches
from the subsequent primary at about the same
point , may occur; the largest very flattened
(mechanically) specimen has a similar ornamen­
tation but with more definitely clavate periven·
tral tubercles.
DIAGNOSIS. This species is characterized
by ts high whorl section, prominent ventral
med1an keel and strong,uniform bar-like prorsi-
F. ETA YO · SERNA
radiate to concave ribs with weD developed pe·
riventral clavi and weak periumbilical bullae .
COMMENTS. This species resembles Peroniceras
moureti Grossouvre (1893, p. 100, pl.
11, figs, 3, 4; text-fig. 37-39), on the latter ho·
wever the ribs are slender and pointed adumbili·
cally and at the same time they develop conspi-
·
cuous elongated periumbilical bullae.
·
The suture line of Peroniceras moureti
Grossouvre (1894, p. 94, fig. 37, p. 101, fig.39)
is similar to that of the Colombian species in its
general aspect but in spite of the difference in
size the L lobe in the French species is narrower
and more deeply incised, whereas in the Colombian
species it is fan-like.
Venzo's (1936, p. 101, pl. 9, fig. 1a, 1b)
specimen of "Peroniceras Moureti De Gross',
likewise has thin and acutely bullate adumbilical
end of the ribs.
The specimen figured by Schliiter (1876,
p. 38, pl. 41, fig. 3, 5) as ·mmonites cf. tridorsatus"
and referred by Grossouvre to his species,
has slender ribs with tubercles farther away
from the umbilical rim and a higher section than
is typical of Grossouvre's species. The ontoge·
netic development of the whorl section shown
by Schliiter (pl. 41, fig. 5) adds height very
slowly but the tricarinate stage is rapidly ;cquh
·
red.
The specimens re ferred by Young (1963,
p. 73, pl. 26, fig. 5, pl. 27, fig. 1, text-fig. 13)
to Peroniceras moureti (Grossouvre , 1894), differ
from the Colombian species by their crowded,
well rounded, strong and conspicuously ad orally
concave ribs; their whorl section is markedly
subquadrate also.
OCCURRENCE. Cucaita Member. Lower
Coniacian.
•.,1'._, ..... "-
This species is named in honor of the geo·
logist Alvaro Guerra.
2·- J-E-!-·o .. -n-c;
. -

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 95
1968 Prionocycloceras longispinata (Basse),
Etayo-8erna, p. 45, fig. 13, Tab. 1.
1972 Prionoeycloceras longispinata (Basse),
· ; Etayo-Serna, p. 48. .,, .
Hipotype. C-134 (U.N.C.M.H.N.C.P.Hy .N. 44).
Only an internal mold is available. Conch
involute, compressed, the umbilical wall is short,
rather sloping, merging into the side with a
rounded umbilical rim. The flanks are weakly
cpnvex, they connect to the planifastigate ven- ..
ter through weak shoulders.
The ornament consists of ribs beginning
at the umbilical rim with small bullate to conical
tubercles; the ribs are radial on the adumbi·
lical third of the flank, they describe an arc on
the middle of the flank and an adoral concavity
on the adventral third; the ribs widen progressively
toward the periventral margin where they
end at clavate, adventrally pointing tubercles
which adaperturally become parallel to the ventral
median line and comute. There are 6 ribs
on two thirds of the last whorl.
Wherever the test is preserved its surface
is covered with striae that parallel the ribs, they
cross the venter in an acute V with its apex adoral.
Between the primaries there may be a riblet
with a similar trend but without tubercles. The
ventral median line is raised as a fine dentate
carina. The ribs tend to split longitudinally. The
intercostal distance varies from one to four times
the width of the ribs.
B) Up to 65 mm D (C-134). At this stage
the ribs are much wider, consequently, the intercostal
space varies from one to one and a
half times the width of the ribs; the ventral region
becomes obtuse.
The suture of this specimen has a tall, ramose,
and bifid E/L saddle and a deep L lobe
with vertical notched sides; L/U saddle is trifid
with subquadrate accessory saddles.
DIAGNOSIS. This species is characterized
by its moderately convex to flattened subrectangular
whorl section and its broad flexuous
ribs.
Measurements D Euw · H W D/Euw%
c- 134 so 13 22 15? 26
c- 134 65? ? 30 22? ?
DfH%
44
?
COMMENTS. Basse (1950, p. 245) proposed
Donjuaniceras as a subgenus of Peroniceras,
with "Donjuaniceras longispinata Basse" as
type species; Basse considered "Prionocyclus
ayabanus Steinmann"as described by Gerhardt
(1897, p. 197, pl. 5, fig. 22a, b) as to
"offre tous Ies caractlres du genre Donjuaniceras
et se place au voisinage des especes precedentes".
Basse's subgenus became a synonym of
Prionocycloceras Spath (1926).
. AHhough I am interpreting Basse's species
In a rather broad sense, in my opinion, it diffP- rs
from Prionocycloceras guayabanum (Steinmann)
[see Gerhardt, op. cit.] which has the periventral
tubercles inclined tOward the ventral median
line with a knob-like aspect; the tubercles are
clavate and abventrally inclined in Basse's spe·
cies, furthermore the latter is a more slender
species; the intercostal spaces are also larger.
• The specimen I previously referred to Basse's
species was compared to plaster carts of Basse's
species.
The specimen figured by Biirgl (1957, pl.
14, fig. 5, ex. spec. HB 31/10 SGN?vlP) asPrionocycloceras
guayabanum (Steinmann) from
the Nariiio Section of Girardot, has a more rapidly
widening venter and a more subquadrate
whorl section than the holotype of Basse's species.
Priono$floceras J2.0rtarum n. se. - .
-pr.·n, 'ij. l'2; Pn4; fij:1;"Text-fig: 9N.
Holotype. C-134 (U.N.C.M.H.N.C.P.Ht.N. 81).
Only the holotype is available. The conch
is moderately evolute, the whorl section is subrectangular,
it has an obtusely fastigate venter;
the umbilical wall is oblique and rounds smoothly
into the subparallel flanks that then round into
the venter without a shoulder.
The penultimate whorl has wide, flattened
ribs of which every other or the third one is
stressed and develops a periven tral bullate to
conical tubercle; on the last whorl the intermediate
ribs are considerably weaker and the ornament
appears as if only rounded prominent primary
ribs were present; the ribs, usually but not
always, start at rounded prominent periumbilical
tubercles, they describe an adoral arc on the
adumbilical half of the flank and a sharp concavity
on the adventral half; the ribs end at prominent
cornute tubercles that are inclined toward
the median ventral line; the sinuosity of the ribs
may be more or less accentuated.
The growth lirae are biconcave; on venter
they form an acute adorally pointing V; on
the periventral margins the fine intercalary ri·
blets and growth striae ('?) may be so prominent
as to be easily observable. The intercostal space
increases ad orally and is from two to three times
the width of the ribs: there are 6 ribs on the last
half whorl. The median ventral line is raised as a
fm ely denticulated carinae.
DIAGNOSIS. This species is characterized
throughout its ontogeny by: A) the elimination
of the intercalary ribs that are later represented
only by prominent riblets on the periventral
margin, B) the rapid ontogenetic development
of comute periventral tubercles.
Measurements D Euw H W D/Euw% D/H%
C·134 49 18 20 16 37 41
COMMENTS. The nearest similar species
is "Prionocyclus mediotuberculatus Gerhardt

96
(1898, p. 198, figs. 23a,b,c), which differs by
its more widely spaced ribs (13-14 per whorl);
the presence of intercalary riblets along the periventral
margin in P. portarum, the subdued
mediolateral tubercles in Gerhardt's species.
The specimen referred to Gerhardt's species
by Biirgl (1957, pl.14, fig.4a,4b), from an
unknown locality, is not in my opinion conspecific
with Gerhardt's species because it has in·
tercalary ribs on the external half of the flank
which have strong centrolateral inflations and
the primary ribs are few.
Prionocycloceras portarum differs from
Prionocycloceras acutospinatum (Basse) (1950,
p.247, pl. 11, fig. 5-6) by the strong omamenta·
tion early in the ontogeny and the strongly ar·
cuate ribs on the flank of the latter.
OCCURRENCE. Lower Coniacian.
-'··-,., .... ,
This species is.named in honor of the Geo
logists Jaime and Nuria de Porta.
PrJangnclo c; eras M ). cucaitaw..s._ ll· _ sp.
Pl. 14, fig. 9, Text- 1g. 9M.
1968 Prionocycloceras (?) aff. P. lenti (Gerhardt),
Etayo-Sema, p.45, fig.13, Tab.l.
1972 Prionocycloceras aff. lenti (Gerhardt),
Etayo-Sema, p. 48.
Holotype. NRC-5 (1965) (U.N.C.M.H.N.C.P.
-Ht. N. 82).
Only the holotype is available. The conch
is discoidal, relatively involute, with the whorls
overlapping to the adumbilical fourth of the
flank; along the umbilical margin of the penultimate
whorl there are small crescentic folds
but the flanks are smooth except for the
growth striae; on the last whorl the periumbili·
cal tubercles are mammillate with their apices
slightly inclined inwards; the ribs arise in pairs
from these tubercles; on the ad apical half of the
last whorl there are fine ribs which describe an
elongated S on the flank and end periven trally
in tubercles with a chisel like point and a
q1,1adrate base and are obliquely inclined to the
median ventral line; at this point the intercostal
space is subequal to the ribs, but adorally ribs
become more distant and wider.
On the adoral half of th last whorl the
periventral tubercles. are parallel to the median
ventral line and moderately enlarged laterally
and outwards. The intercostal whorl section at
the adapical end of the last whorl is fastigate; at
the adoral end it is subrectangular, it has an
accentuated overhanging umbilical wall which
merges through an angular umbilical rim into
the flanks which are inflated on the adumbilical
half and excavated to compressed on the adven·
tral half; the sides round smoothly into the al·
most tabulate venter which has smooth carina
along the ventral median line.
F. ETA YO - SERNA
The specimen is completely septate
and missing its living chamber. The growth lines
follow the trend of the ribs, they cross vente!
forming an acute V with apex pointing adora·
Jly. On the adoral fourth of the last whorl there
are 8 tubercles.
DIAGNOSIS. This species is characterized
by its change in whorl section from Castigate
to truncate, by the numerous ribs which arise
in pairs from spinose umbilical tubercles and
end in comu te oblique tubercles.
MeB!IIlrements 0 Euw H W 0/Euw% D/H0"
NRC-6(1965) 64 17? 26 18 28? 40
COMMENTS. Prionocycloceras (?) cucaitaense
n.sp., resembles "Gauthiericeras lenti" Ger·
hardt (1897, p.77, pl.l, fig.4a, b; text-fig.3; non
Reyment 1958, p.12, non Matsumoto, 1965,
p.45); Gerhardt's species is more fm ely costate
with 17-18 ribs per half whorl and has weak pe·
riumbilical tubercles; on the contrary, the new
species has a sparse ribbing.
''Ammonites barbacoensis" Karsten (1858,
p,111, pl.4, fig.5) has even greater similarities in
the shape of the whorl section, involution, type
of ribbing, and tuberculization, but they diffex
by the wavy carina at the adoral portion of the
conch ["dorso acutiusculo late tuberculato", ib.
p. 11]; P. (?) cucaitaense lacks the tubercles.
The association of Karsten's species with
"Ammonites Tucuyensis von Buch" is incorrect
the latter species comes from La Puya Membex
of Albian Age (Renz, 1972, p.704, 719). Kars·
ten (1858, p. 111) noted that "A Barbacoensis
. . . kommt selten neben dem Leonhardianus m.,
varicosus Sow., Tucuyensis Buch • . . bei Barba·
coas ... ," but later (1886, p.18) he reported a
more reliable association near Barbacoas (Vene·
zuela): "A. Leonhardianus Krst . . . A. toroanlfS
Krst . . . A. Mosque rae Krst . ..
etA. Barbacoen­
sis Krst . .. {see also Karsten, op. cit., p. 62];
these ammonites probably come from the La
Luna Fomiation and perhaps represent two
different biostratigraphic horizons. "A. barbacoensis"
Karsten represents an unnamed genus
re:ated to · Prionocycloceras (as observed by
Gerhardt, 1898, p. 193), rather than being
congeneric with it.
OCCURRENCE. Cucaita Member. Lowe!
·
Coniacian.
-
Genus t{;IOTiceEDs : .. :.
/}'''d. /\ '
- - f ilia.: -- -'- r;·"lfi; {.}.'-
TYPE SPECIES. Gloriace1Tl$ correai n. sp.
DIAGNOSIS. Conchs small to mocMrately
large. The earliest whorls observed are discoidal
with .fastigate, unicarinate median ventral re·
gion; the ornament consists of faint falcoid ox
biconcave ribs that cross the venter in an acute
adoral bend; the ribs mar-bifurcate on the urn·
bilical third of the flank, at this stage no tuber·
cles are developed.

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 97
Shortly after, the ribs weaken on the median
ventral line and develop a rounded somewhat
spirally elongated external lateroventral
node; the admedian ventral end of the ribs
elongates longitudinally and which soon inter·
connect fonning almost continuous keels on
each side paralleling the median keel but the
ribs can still be observed crossing the venter.
The ribs sporadically develop weak periumbili·
cal swellings. With growth the ribs tend to stra·
ighten on flanks, become club-like and connect
the ventrolateral carinae.
The periventral tubercles are much stron·
ger than the periumbilical ones which someti·
mes are missing. The suture line has E/L saddle
large, rectangular and bifid with the external
branch foliate and narrow at its stem; L lobe is
wide, deep, bifid (pseudotrifld); L/U2 saddle is
slender, taller than E/L saddle, bifid, phylloid;
U2 lobe is digitated, short. U2/U3 and U3/U1
are subequal. U3 lobe is digitated, glove-like;
.U1 lobe is bifid, narrower but as deep as U2;
U1/l saddle is single, witn' a unique phylloid
head.
COMMENTS. This new genus resembles
Peroniceras Grossouvre (1894) from which it
differs by possessing an early initial stage with
flexuous bifurcating ribs that cross the carinate
venter forming chevrons, a character retained in
some adults but absent in Peroniceras [see for
instance Peroniceras dravidica Kossmat, (1895,
p.190, pl.23, fig.3)], and by having undulated
ventrolateral carinae. Major differences are present
on the suture line.
The suture line of Peroniceras as figured
by Grossouvre (1894, p.44, text-fig.37) has
a wide E/L with a narrow, highly incised digitated
L. U2{U3 saddle is accessory to L/U2; such
interdependency of L/U2·U2/U3 saddles is also
observable on "Peroniceras cf. dravidicum Kossmat
sp." as illustrated by Spath (1921, p.295,
pl.23, fig. 1d) (which incidentally is the only
example of the entire suture of a Peroniceras
known to me);in the latter species U1/I saddle
is trifid.
"Peroniceras " leei Reeside (1927, p.40,
pl.43, fig.3) has a suture with U2 and U1 separated
by a tall bushy U2/Ul. The Gloriaceras al·
so resembles Pro texanites Matsumoto (1955),
as exemplified by "Mortoniceras bourgeoisi d'
Orbigny" in de Grossouvre (1894, pl. 14, figs.
2a, 2c), from which it differs by the early development
of the keel, the more flexuous and numerous
initial ribs, the slenderer but more dis·
sected elements of the external suture and by
the better defined and raised umbilical saddles.
Of the non-Colombian species known to
me congeneric fomlS would be represented by
some of the specimens described by Burckhardt
(1919, p. 109) as "Peroniceras cfr. subtricarinatum
Sturm, non D'Orb, et auct.", especially the
specimen showing the last· suture and the living
chamber (Burckhardt, 1921, pl. 27, fig. 5); the
:Mexican specimen seems more evolute than the
Colombian one and its E/L saddle is also m

98
the flank and have a periventral ovate clavus
from which they extend onto the venter.
The median ventral carina is high, slightly
Wldulated and separated from the ventrolateral
carinae by shallow, asymmetrical sulci. Adaperturally
the whorl section becomes lower; the ribs
may bifurcate {rom the umbilical rim or near
the middle of the flnak.
On the adoral part of the last whorl the
section becomes subquadrangular, the ribs are
club-like on the flanks and at the connection
with the ventrolateral keels, clavi-like undula·
tions of the carinae develop as if the latter were
tuberculated; the ventral margin clavi become
strenghtened and periumbilically the ribs tend
to develop clavate swellings.
DIAGNOSIS. This species is characterized
by the slow ontogenetic cl)ange of its ribbing
from fm e and biconcave in the early whorls to
strong, straight, club-shaped ribs in the later
stages; likewise the change in whorl section is
slow.
Measurements D Euw H W D/Euw D/H No.R.
Ofo %
NRC· Ca · 1·6 66 27 23 20 41 36 14
COMMENTS. This species resembles that
described by Burckhardt (1919, p. 109; 1921,
pl. 27, especially on fig. 3) as "Peroniceras cfr.
subtricarinatum Sturm, non D'Orb. et auct.",
but the nbs are finer and sharper on the latter.
The Mexican species also has more closely spa·
(!ed ribs.
G. c orreai n. sp. differs from G. paulinae
n. sp . because on the latter the ribs change
through the ontogeny from biconcave to stron·
gly concave ad orally. Earlier (Etayo • Serna,
1968) I identified G. correai n. sp. as "Peronice­
ras cf. Czomigi", having compared it to figure
2a of plate 11 of Grossouvre's paper; in the
French species, however, the illustrations indi·
(!ate that the lateral keels are continuous, not
onnecred to the marginal tubercles.
Furthermore, the ribs are concave ado·
rally on the adumbilical third of the flank up to
a size where they are completely strait on the
Colombian species which likewise has umbilical
bullae that are lacking in the Grossouvre's (op.
cit., p. 103) illustration.
OCCURRENCE. Cucaita Member. Lower
Coniacian.
Gloriaceras rgzulinae.!bJJ!.
.__,._,Pl. U,'Iig.·t ·;Text-figS': 9K, 9L.
fiolotype. NRC-Cu5 (U.N.C.M.H.N.C.P.Pt.N.84)
Paratype. (U.N.C.M.H.N.C.P.Pt.N. 73).
There is one internal mold available. The
second (?) whorl is subeUiptical in section,slightly
higher than wide, the maximum width is at
the umbilical rim, the flanks gently converge toward
the arched venter; on the third whorl the
section has doubled .its height: the periventral
..
F. ETA YO · SERNA
region Is broadly rounded and there is a keel
along the median ventral line paralleled by
weak grooves.
On the fourth whorl the section retains
the preceding proportions but the flanks are
slightly more flattened and two lateral carinae
paralleling the median keel are visible on the
adoral part of the third whorl; the flanks are
smooth but at the adapical part of the fourth
whorl, prorsiradiate, weakly biconcave ribs begin
to develop from the umbilical rim and extend
onto the venter ending at the ventrolateral
carinae, at this stage the periventral clavi are on·
Iy weakly indicated; soon thereafter the ribs begin
to show clear periventral clavi and more or
less contemporaneously bullate swellings deve·
lop on the ribs along the umbilical margin; on
the flanks of the fourth whorl the ribs describe
a well defined adoral concavity. The intercostal
spaces are slightly wider than the ribs on the in·
ternal mold.
B) Up to 50 mm D fVL-6-Cu-1(1966)].
The conch is septate throughout, the ornament
of the penultimate whorl is the same as on the
small specimen al though the concavity of the
ribs on the flanks is less obvious because the
test is still present; on the adapical third of the
last whorl the concavity of the ribs on the
flanks becomes conspicuous, the ventrolateral
clavi are depressed and outwardly inclined.
The living chamber occupies two thirds of
the last whorl and on it the ribs are strongly
concave and very prominent. On this specimen
all three ventral carinae are only slightly wavy.
DIAGNOSIS. This species is characterized
by the quick ontogenetic change of the ribs from
sickle shaped in the early whorls to strongly
concave adorally on the later whorls; the whorl
section changes more rapidly in height than in
width.
Measurements. D Euw H w D/Euw D/H No.R.
% %
NRC· Cu • 6 38 16 13 10 39 34 21(1/'Z)
VLG • CU· 1 52' 20 19 15 38 36 33
(1966)
NOTE: Specimen VL6-CU-1-(1965) was measu·
red to the end of the phragmocone only.
COMMENTS. Gloriaceras paulinae n.sp.
differs from the specimen figured by Burckhardt
(1921, plate 27, fig.5) which is characterized as
noted by Burckhardt (1919, p.llO) : "Un ejem·
plar (Iam.XXVII, fie.5) se aparta de los otros oor
sus costillas mas rObustas y mas distanciada5 ya
en Ia juventud, y parece representar una especia
distinta, como lo indica tambien la sutura que . ..
se acerca a un tipo de linea sutural caracterlstico
para el genero Mortoniceras . . . . ", because of
its smaller size, lesser involution and weaker ribs.
The other specimensaescn"bed by Burck·
hardt (1919) and illustrated later (1921, pl. 26,
fig. 1-12, but especially figs. 4,2, 'the latter ex·

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 99
elusive of the suture line) might be conspecific
with the Colombian species.
The specimen described and illustrated by
Stunn (1901, p. 60, pl. 3, fig. 5, 5a) as "Peroniceras
subtricarinatum d'Orb. ·5pec." to which
Burekhatdt compared his specimens (1919, p.
109) shows at the stage of growth illustrated
by Sturm (D:39mm approx.) a similar ornament
to that of the adult of Gloriaceras pauli­
nae n.sp. however, from Stunn's comments (op.
cit. p.60), "Den Beschreibungen durch friihere
Autoren ist nur hinzuzufligen, dass bei zuneh·
mender Gro55e der lndividuen die drei Riicken·
kiele immer mehr schwinden, so dass schliesslich
der- Durehschnitt des letzten Umganges spitz-:.
oval wird", that is to say that on the European
species the ventral carinae attenuate and the
whorl section becomes acute-oval with growth;
this signifies that the ontogenetic development
df Sunn's "species" is opposite to that of the
Colombian species.
COMMENTS. The "subgenus" Zumpangoceras
was proosed by Basse (1948) in her
study of the European and Madagascan species
of Barroisiceras. By studying my material from
Colombia and through the perusal afBurckhardt's
paper, im seems clear that although all of Burck·
hatdt's "Barroisiceras , . share some common
characteristics, not all of them share the same
ontogenetic development.
The ribs are dominantly biconcave (:IW oll!l@'.eg!!!i _-u.,. !li · - ·'-.""' "" .
..
, · -
jection; . a median ventral clavus whih alternates
w1th ventrolateral clavate to obhque tu·
Zumpangoceras Basse, 194 7, p. 144.
bercles; the lateral tubercles become stronger
with growth, they tend to migrate toward the
TYPE SPECIES. Zumpangoceras burckhardti center of the flank from a more internal posi·
Basse, original designation. tion and dominate over the periumbilical tuber­
Lectotype of Z. burckhardti cles; the early whorls with tectiform ventral re·
the specimen described by
Burckhardt (1919, p.98 and
later illustrated as Barroisice­
gion which subsequently becomes truncated or
even weakly excavated with growth.
ras sp. ind.num. 7 by the same
The specimen figured by Burckhardt on
author (1921, pl.23 fig. 1), his plate 22, fig. 16, is here interpreted as cons­
here designated.
pecific with the lectotype of Z. burckhardti;
the specimens described as Barroisiceras sp. ind.
num. 7 (op.cit.,pl. 25, figs. 16, 17) are here in·
terpreted as probably congeneric but not cons·
pecific with the lectotype.
Zum l a inai n. sp P: ""'· ·='"·---·--..
Prr, 1gT; ext-ffgs. 9o, 9 .
1968 l''orresteria (Forresteria) cf. F. allaudi
(BLT). Etayo-Serna, p.45, fig. 13, Tab. 1.
1972 Forresteria (Forresteria) cf. allaudi (BLT),
Etayo-Serna, p. 48.
Holotype. NCR-1 (1965) (U.N.C.M.H.N.C.P.Ht.
N. 85).
Paratype. (U.N.C.M.H.N.C.P.Pt.N. 74).
A) Up to 30 mm D (VL-6-Cu5). At the
adapical fourth of the penultimate whorl the
section is fastigate, senate along the median line;
there are rounded periventral to clavate tuber·
cles, the sides are ornamented with flattened
flexuous ribs, they begin at the umbilical rim
and internally to the middle of the flank they
bifurcate; one intercalary rib appears near the
middle of the flank and between a pair of
bifurcating ribs. Midventral and periventral
tubercles alternate, the fanner being adoral to
the latter.

100 F. ETA YO - SERNA
On the adapical third of the last whorl
the ornament follows the pattern previously
described, the ribs are accentuated and have the
shape of an elongated S, they extend on venter
and interconnect at the median ventral clavi.
The whorl section becomes subrectangular;
the umbilical wall is low and vertical, it
rounds abruptly intO the flanks which are convex
on their adumbilical third, then they weakly
converge toward venter forming a rounded ventral
shoulder; the venter is raised· along the median
line but it becomes slightly excavated on
each side. At this stage some ribs have weak periumbilical
bullate swellings.
On the adoral half of the last whorl the
section becomes more inflated on its adumbilical
third and the venter becomes wide, almost
truncate; at the boundary between adumbilical
and central thirds of the flank some ribs de\lelop
a subtriangular prominent tubercle, at the same
time the periventral tubercles enlarge outwards
but they are clearly compressed_ d clavate.
B) Up to 50 mm D (NRC-1 (1965)). This
specimen includes the adult (?) liVing chamber.
It is involute, the intercostal whorl section is
suboval: the umbilical wall is short, subvertical,
it merges rather abruptly into the convex flanks
that in tum round bto the broadly arched
venter.
The ornament consists of ribs most of
which start at the umbilical brink in a claw-like
manner,· they begin as sharp points and
thicken outwardly, they also bend backwards
slightly on the adumbilical third of the height
of the whorl; just internally to the middle of
the flank the ribs develop a prominent pyramidal
tubercle and from it the ribs run forward
ending .periventrally in a thorny, clavate and
outwardly directed tubercle; the ribs may bifurcate
from the lateral tubercle with one of
the branches joining either the following adoral
or the preceding adapical periventral tubercle
(which th(ln appears to join two ribs coming
tonn different nodes) in such a manner that the
ribs seem _ to form a W on the flank; this does
not alwayspccur on the opposite side, however.
Some ribs may have a slight periumbilical
node or they may bifurcate periumbilically
with one branch joining the subsequent submedial
tubercle. The ribs are broad, low, and tend
to split lQngitudinally on the adventral half of
the flank: The intercostal spaces are broad, one
and a half times as wide as the ribs; shallow.
Along the median ventral line there is a
row of prominent clavi, adoral to the priventral
tubercles at the vertex of the linguiform
projection of raised lirae (rib lets?) on venter.
The growth striae are impressed on the
ribs on the internal mold; on venter the ribs
themselves are absent but the raised growth
striae cross it in the wide adorally linguiform
arc; the preserved fragment represents the living
chamber, there are 10 periventral clavi and 8
subcentral lateral tubercles.
DIAGNOSIS. This species is characterized
by: A) its great involution, B) the ontogenetic
development of its ornament: the siphonal and
penventral tubercles appear first followed by a
weak periumbilical and finally, a sub-mediolateral
tubercle, the latter at first are nearer the wnbilical
third of the flank and then slowly migrate
upwards toward the middle of the flank but
never attaining an exactly medial position but
becoming stronger with growth, C) the change
in the shape of the venter from fastigate to almost
truncate and wide.
MeastUemeata. D Euw H W D/Euw D/H
% %
VL6 • Cu5 30 5 16 12 17 63
NRC-1 (1966) 60 10? 22 20 20 44
COMMENTS. The small juvenile specimen
resembles Forresteria stantoni Reeside (1932,
pl. 7, figs. 1· 7) which has a very strong ribbing
earlier in the ontogeny than the Colombian species.
Furthermore, its ribs are club-sh aped and
more numerous than in Z. osplnai n.sp., the lateral
tubercle en Reeside's species is cen trolateral to
adventral, contrary to that of the new Colombian
species where it is at first adumbilical in
position, later migrating toward center of the
flank.
The large Colombian specimen resembles
Forresteria (F. ) allaudi (Boule, Lemoine and
Thevenine)[1907, p. 32, pl. 8, fig. 6; malformed?l,
however, the whorl section in the most
similar specimens is very depressed as with the
specimen illustrated by Boule, Lemoine and Thevenine,
or the one by Basse (194 7, pl.8, figs.3,3a)
from the "Con_glomerat ferrugineux Ambohimarina,
Mont Carre"; however, on the Madagascan
specimens the vertical distance between the
periventral and the lateral tubercles is shorter
than the distance between the latter and the
umbilical tubercles, the opposite of the Colom·
bian species.
Likewise on the Madagascan species the
ventrolateral tubercles are heavy and conical
whereas in the Colombian species they are com·
pressed, clavus-like, upwards and outwardly
directed. ForresteriD {orresteri Reeside (1932,
pl.5, fig. 5) has a subquadrangular whorl section
rather than higher than wide as on the Colom·
bian specimens; the siphonal clavi of F. forresteri
Ft.eeside are elongated, and the ribs club-shaped
whereas on the Colombian species the ribs are
curved and have a tendency to splitlongitudinal·
ly.
Matsumoto (1969, p. 308) has discussed
the Indo-Pacific species, he considered Reeside's
species a synonym of the Madagascan species.
Whatever may be the case, it is clear that the
Colombian species differs in the ontogenetic
development of its nodes and pattern of ribbing
and belong to a different group than the
Indo-Pacific species.

ZONATION OF TH E CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 101
The specimen referred to the Madagascan
species by Benavides-Citceres (1956, p.478, pt
61, fig. 1) is too poorly preserved to warrant a
comparison. On the specimen illustrated by
Burckhardt ( 1921, pl. 25) in his figure 17, the
ribs are raised, ridge-like between the lateral
and umbilical tubercles, consequently, the lateral
tubercles are not well individualized, they
are fine, subrounded in the Mexican species; the
opposite of these characteristics occur in the
Colombian species.
Incidentally, this figure 17 of Burckhardt's
plate 25 (1921) seems to show the migration of
the tubercles toward middle of the flank.
OCCURRENCE. Cucaita Member. Lower
Coniacian.
,... ....,... .#/ ·.J.-..... .-
This species is named in honor of the geologist
Carlos Ospina.
•
Holotype. N.R.C - Sora (U.N.C.M.H.N.C.P.Ht.
N. 68).
The innermost whorl observed (third?) is
twice as high as wide; the maximum width on
the adumbilical third of the flank; externally
from the maximum width the flanks are flat to
excavated and converge toward the venter that
has inclined sides. The next whorl covers two
thirds of the height of the preceding whorl, the
ad umbilical third of the flank is clearly convex;
the remaining part of the flank is flat and weakly
converges toward the venter into which it merges
across the shoulder.
The ornament consists of ribs which begin
at the umbilical rim with a rounded to bullate
tubercle, they trend radially to near the mid·
die of the whorl where they develop a weak
round node from which the ribs may bifur..:ate,
the adventral branch is slightly adorally arcuate
across the venter; at the ventrolateral margins
the ribs develop clavi that are subparallel to the
median ventral line; riblets interconnect the median
ventral and the lateroventral tubercles.
Early in the ontogeny, the ribs are narro·
wer than the intercostal spaces, later they become
broad, club-shaped, wider than the intercos·
tal spaces especially on the adventral half of the
flank. The increase in umbilical width with
growth is quite •significant.
DIAGNOSIS. This species is characterized
by: A) the decrease in the distance between the
ribs with growth, B) the ephemeral development
of the small, rounded lateral tubercles, C) the
stressing with growth of the periumbilical tuber·
cles and the increase of the umbilical width.
Measurements D Euw H W D{Euw D/H
Sora NRC 40 7 22 14 17% 1:15%
NOTE : The measurements refer to the entire
part of the conch only.
COMMENTS. The only species·known to
me that is comparable is ''Barroislc. aff. als·
tadenense Solger, non auct', decribed by
Burckhardt (1919, p.105) and subsequently
illustrated (1921, pl.25, tig.10) but on the
Mexican species [=Zumpangoceras] the ribs are
finer, more crowded and more prominent and
the periventral tubercles are very attenuated,
likewise its umbilicus does not seem to widen
• with growth.
OCCURRENCE. Cucaita Member. Lower
Conician.
Genus
TYPE SPECIES. Buenoceras loboi n. sp.
DIAGNOSIS. Conch discoidal, moderate·
ly involute, maximum inflation near middle of
the flank from which the flattened sides round
toward the umbilicus and the periventral margins;
the venter is tectiform; the early whorls
are ornamented with fine ribs that " appear
smoothly at the umbilical margin; they are
weak on the flank but on the adventral third
they are stronger; there are ventrolateral
tubercles that are inclined toward the ventral
median line, the ribs then cross the venter in an
acute V with an acute clavus at the vertex; on
later whorls weak ribbon like biconcave riblets
arise in bundles from tenuous periumbilical
swelling; they may bifurcate near the middle of
the flank where they are a little wider but do
not develop a tubercle . In the adults all ribs end
in oblique claw-like tubercles which are connec·
ted through the prolongation of the ribs with
the ventral median clavi.
COMMENTS. This genus differs from
Zumpangoceras Basse (194 7), by the absence of
lateral tubercles which are stressed with age.
From "Schloenbachia " flexuosa Gerhardt
(1898, p. 157, pl. 4, fig. 1a,1b,1c) from Upper
Coniacian beds of Colombia which has a whorl
section with the inner half of flanks weakly excavated
to flat, whereas the moderately excavated
external halt" of the whorl converges toward
the venter; the inner whorls of "S. " {lexuosa
have venter fastigate, later in ontogeny the ventral
zone widens, the ventral median keel is depressed
and the venter becomes almost trunca•
ted;on the internal whorls the lateral ornament
consists of low flexuous ribs, which develop
oblique ventrolateral claw-like tubercles and
continue to midventer; on subsequent stages,
the ornament is composed of bundles of falcoid
to falcate raised lirae that define very low
ribs, they extend onto venter forming an acute
siphonal V, the ribs develop a row of ventrolateral
tubercles subparallel to the ventral median
line.
These ventrolateral tubercles are .elevated
adapically and thin and project slightly obliquely
and ad orally; on later stages the rib; and periventral
tubercles are suppressed and only raised
lirae with an accentuated concavity on the ad·

102
ventral third of the whorl side are present (the
two later stages are illustrated on Gerhardt's
figure 1; plate 4, 1898); the sum of the precedign
characteristics differentiate clearly both
taxa.
This genus is named in honor of Professor
Jesus A. Bueno of the Department of Geocien·
cias U. Nal. of Colombia.
·-·-, .• .liJrGergs I,Qboi n. m.
--· . . PI.l ;fig. 2; Text-fig. 9R, 9U.
Holotype. NRC-4 (1965) (U. N. C. M. H. N. C.
P. Ht. N.87).
Paratype. (U. N. C. M.· H. N. C. P. Pt. N. 75).
The adapical segment of the second whorl
has a subcylindrical section; at an equivalent
position on the third whorl the section is twice
as high as .wide and ventral median clavi occur
on the adoral portion of this whorl; the flanks
have an even curvature from the ventral median
clavi to the umbilical rim.
The umbilical wall is curved and bends
toward the venter of the preceding whorl. On
the fourth whorl (D: 15 mm) the venter is tectiform
and has diverging flat ventral sides which
round smoothly into flanks; the latter have
their maximum width adumbilically near the
middle.
Every whorl overlaps to a point slightly
adumbilical of the middle of the flank of the
·
preceding whorl.
The ornament on the last PJ't!&erved whorl
consists of ribs that arise from rounded swellings
at the umbilical rim, describe a weak
concavity on the adumbilical third of the flank,
then trend prorsiradiate to near the middle of
the flank, from which point they describe a wi·
de adoral concavity. The ribs are flat, ribbonlike;
at the periventral margins the ribs develop
an oblique claw-like subelliptical thickening,
from these nodes the riblets or Iirae connect
with the ventral median clavi in a manner such
that venfA!r is crossed by an array of acute Vs.
The suture line has L asymmetrical; the
sanddles are subrectangular, symmetrically to
subsymmetrically bifid; U2 is oblique.
The laceration of the different elements
of the suture line is very variable even on both
sides of the same suture.
- . ' - . ; ..
· .. .
DIAGNOSis: ' This species is characterized
by: A) its biconcave to falcoid ribs that coalesce
at low rounded tubercles on the umbilical
rim, some of them bifurcate near the middle
of the flank without forming a tubercle , B) the
claw-like periventral tubercles and elevated median
ventral row of clavi.
F. ETA YO · SERNA
Measurements
NRC-Sora
NRC·4
D
?
?
Euw
?
?
COMMENTS. · The only foreign species
known to me that compares with this species is
Reesidites minimus (Hayasaka and Fukada) type
species of Reesidites Wright and Matsumoto
(1954), however, the latter has prominent
strong ribbing very early in the ontogenetic development
(see Hayasaka and Fukada, 1951,
pl.l), the opposi is true of the Colombian species,
on the latter the ventrolateral nodes are
oblique to the median ventral line but in Reesidites
minimus they are parallel to the siphonal
line (See Matsumoto, 1965, p 61, pl.64, fig.
34a; holotype, pl.14), finally (and not critical?)
the suture lines are different: in the Japanese
species E/L saddle is asymmetrically bifid with
the adventral branch conspicuously shorter
than the external branch (see Matsumoto,
p.64, fig. 34b, holotype).
More similar, though, and here interpreted
as congeneric, is·the Mexican species represented
by "Barroisicera sp. ind.num.3", of
Burckhardt (1919, p.102) and subsequently
illustrated by him (1921, pl.24, fig.10); from
the illustration, the Mexican species has closer
periventral tubercles and a more accentuated
bend of the low ribs at middle of the flank than
on the Colombian species.
Biirgl, 1954a, recorded a "Barroisiceras
subtuberculatum (Gerhardt)" (ex.spec. HB-216
SGNMP), which seems to be a member of Buenoceras
loboi n. sp., however the former seems
thicker and has stronger ribs than the latter.
OCCURRENCE. Cucaita Member. Lower
Conician.
"\""''\ ' . c , ..
This species is named in honor of the
Engineer Ramiro Lobo of the Ministerio de Mi-
·
nas y Petroleos.
H
16
30
Genus. nsygnjteshatsumoto,
.._, 1. !Pt!lt . IlL . '- Qlr ).
-·. -
Protexanites Matsumoto, 1955, p.3.
TYPE SPECIES. ''Mortoniceras" bourgeoisi
(d'Orbigny) Grossouvre
(1894, p.73, J)l. 13, fig.2; pl.,
14, fig.2-5) [sic], orial desig-
·
nation.
w
10
18
fro{g!'n.ti£st_,ucqiV,Je-
Pl.l ,fi'gs. ,4; 'rexr.Ji
1968 Protexariites caiiaense (Gerhardt), .Etayo­
Sema, p.45, fig.13, Tab. I.
1972 froiexanites canaense (Gerhardt), Etayo­
Serna, p. 48.
Holotype. VL6-Cu-3 (U. N. C. M. H. N. C. P.
N.88).
The first whorl of the conch has a vaulted

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 103
section; it is slightly wider at the umbilical margin
and has weakly convex or subparallel sides
' that evenly round into the broad fastigate venter;
the umbilical wall is oblique and rounds
abruptly into the sides; the second whorl is subquadrate,
the flanks are flat between the umbilical
and the ventral margins, -the venter is wea­
Idy keeled along the median line, arched from
the keel to the periven tral margin; the flanks
overlap only the external half of the preceding
whorl.
On the third whorl the venter tends to become
flat but keeled along the median line; up
to the second whorl the sides are smooth, but
on the third whorl broad, well separated ribs
begin to appear.
On the adoral half of the fourth whorl
there are eight low ribs most of them with bullate
periumbilical tubercles; the ribs extend
;adially to the periventral margin where they
develop a long triangular spinose tubercle, upon
which abub; against the following whorl.
On the fifth whorl the section is quadrate,
with a broadly rounded umbilical rim and
the innermost part of the umbilical wall weakly
converges toward the venter of the preceding
whorl; the ventral margins are broadly rounded
along the intercostal spaces, they raise into
rounded bulges from which they connect with
the ventral median keel.
There are sixteen ribs on the fifth whorl,
they are separated by intercostal spaces twice
as wide as the width of the ribs, and the periumbilical
bullae are conical; the ribs are wider
and weaker near the middle of the flank. On the
sixth and last whorl the section is as in the preceding
whorl; the growth of the whorls is relatively
slight.
The ribs begin at brink of the umbilical
wall and are inclined adapically, they bend slightly
just outside the umbilical rim and then trend
radially to weakly arcuately across the flank,
they develop periventral tubercles that project
outwards and backwards like a thorn; from this
marginal tubercle the rib continues onto the
venter as a broad triangular ridge at the end of
which one or two clavate, bead like tubercles
are pre,sent; between these tubercles and the
raised median ventral kell there is a wide shallow
sulcus.
The growth striae begin a the umbilical
seam, they slant down about 45 adapically on
the umbilical wall, they then tum forming a
shallow concavity on the adumbilical third of
the flank, describe a weak arc on the central
third and a concavity on the adventral third;
they trend toward the ventral median line forming
a linguiform projection.
At some places on test, especially where
this is limonitized the growth striae can be seen
·to anastomose with each other and form a network;
at places where the test is preserved but
not limonitized the internal structure of the test
.
appears to consist of rhombic compartments but
this is due In twinning of the calcite shell material;'·
DIAGNOSIS. This species is characterized
by: A) its quadrate whorl section, B) ib; radial
ribs with periventral spinose nodes and C) the
shallow and moderatellynarrow sulci .that para-
llel the ventral median keel. · · :; > ·
Me&S\lremeots D Euw H w D/Euw D/H No.R.
% %
VL-6-Cu-3 38 15 15 13 39 39 20
70 30 26 24 43 -7 19
90 36 30 29 40 33 23
NOTE : The height of the whorl was measured
·
over the carina.
COMMENTS. Protexanites cucaitaense p.
differs from "Mortoniceras bourgeoisi (D'Orbigny)"
in de Grossouvre [1894, p. 73, pl. 14, figs.
3a1 3b ),which has the ventrolateral clavi taller
than the ventral median keel on the excavated
venter, contrary to the condition of the Colombian
species; further, on the French species the
umbilical tubercles are radially elongated but
in the Colombian species they are pustuliform;
in addition, the ribs tend to attenuate and widen
near the middle of the flank on the Colombian
species, a trait that is not observed on the French
species.
Pro texanites cucaitaense differs from Protexanites
cagnaense (Gerhardt) [usually mis!pelled
canaense] which has a high, rectangular
whorl section whereas the former has a quadrate
whorl section and shallower ventral sulci
paralleling the ventral median carina; furthermore,
on P. cucaitaense n.sp., there is a persistent
correspondence of two successive ventral clavi
to each marginal tubercle, a trait that is observed
only late in the ontogeny of Gerhardt's
species (1898, pl. 1, fig. 2a, 2b).
Young (1963, p. 66-67) discussed the status
of Protexanites Matsumoto and Prionocycloceras
Spath and seemed to dismiss the valut.!
of the ventrolateral clavate tubercles of Protexanites.
In my opinion, based on the Colombian
specimens available to me, it appears that the
ventrolateral tubercles greatly enlarge with
growth in Prionocycloceras , but on Protexanites,
the tubercles do not enlarge as much and
if they enlarge, they do not obliterate the ventral
clavi, or both weaken concomitantly (see
Grossouvre, 1894, pl. 13, fig. 2; D:150mm).
As observed by Young, and confirmed
by the Colombian material, there are secondary
ribs or riblets intercalated along the periventral
margins on Prionocycloceras, but in Protexanites,
the intercostal spaces are smooth, the
ribs are more distant and rectiradiate; in addition,
the ventrolateral clavi seem to appear
earlier in the ontogeny of Protexanites than in
Prionocycloceras. Incidentally, the type locality
of the holotype of the type species of Prionocycloceras
is not near Chejende, Venezuela,

104
but "Fundort: Von Stiibel im Bett des Rio Guayabo
an der Siidwestseite des Cerro Pelado im
siidlichen Columbien gefunden". (Gerhardt,l898
p. 197; see also Steinmann, 1882, p.169).
OCCURRENCE. Cucaita Member. Lower
Coniacian.
.TH:fHA ....
Family CYMATOCERATIDAE
Genus Heminautilus Spath, 1927
Heminau 4 tiath, 1927, p. 22.
TYPE SPECIES. Nautilus saxbii Morris, ori·
ginal designation.
Heminautilus etheringtoni
Durham.
Pl.4, fig. 8; Pl. 5, fig. 9.
1946 Heminautilus etheringtoni Durham, p.432
pl. 62, fig.4; pl. . figs. 3,5-7, pl.64, fig.
1-3; Text-fig. 3c-f,5.
1947 He minautilus etheringtoni Durham, Durham,
p. 576, figs. 1-3.
1956 Heminautilus etheringtoni Durham, Kum·
mel, p. 335, 436, 437, fig. 201.
1964 Heminautilus etheringtoni Durham, Kummel,
K407, fig. 29K.
1964 Heminautilus etheringtoni Durham, Etayo-Serna,
p. 129.
Hypotype. F- 15 (U.N.C.M.H.N.C.P.Hy.N , .45).·
Only a completely septate internal mold
is available. The conch is very involute, the whorl
section is high, inverted cordate; the umbilical
wall is inclined, it ascends smoothly to the high.
periumbilical area and then merges into the
slightly excavated convergent flanks that bend
abruptly at the periventral margin to form a
rounded rectangular shoulder; the venter is
truncated.
The suture line is adorally arcuate on the
umbilical wall, on the periumbilical area it bends
sharply and trends rursiradiate for a shorter dis·
tance than the internal branch, and then it changes
progressively to form a wide, very regular
F. ETA YO · SERNA
* * *
adoral concavity on the flanks, it crosses the
venter straight, normal to the median ventral
line. In general the shape of the suture line is
that of a sickle with a short handle.
Measurements D Euw H W D/Euw
%
F·15 115 5 75 62 4
D/H
%
65
COMMENTS. The specimens studied by
Durham, excepting that coming from his loca·
lity C (Paratype, U.C.M.P.N. 35735) are slightly
more inflated than the present which, however,
agrees well with Durham's holotype (U.C.M.P.N.
35731) in whorl profile, although on the latter
the flanks are relatively straight whereas in my
specimen they are weakly contracted towards
the adven tral third of the flank.
On this specimen the suture lines cross
the venter normal to the median ventral line
without any indication of a siphonal sinus or
at most only a suggestion of it; in the collection
of the University of California there is a topotype,
internal mold, of He minautilus etheringloni
·Durham (U.C.M.P.N. loc. C-180) which does
not show the ventral sinus, a trait previously re·
corded by Durham (1946, p. 432) for one paratype
(U.C.M.P.N. 33733); on this specimen the
suture line is weakly arched adorally and at one
point it is slightly oblique to the ventral median
line.
On the holotype (U.C.M.P.N. 35731) the
venter of the internal mold is flat, almost trun·
cated but where the test is preserved it shows a
feeble siphonal sulcus: a ventral sutural lobe is
present.
Heminautilus saxbii (Morris) the holotype
of the type species of the genus as illustrated by
Kummel (1956, pl. 10) shows an adventral contraction
of the flanks and its section is less infla·
ted and the ventral sinus is well marked compared
to some equivalent specimens (immature?)
of H. etheringtoni.
The specimen illustrated by Douville {1916,
pl. 17, fig. 2b; see fig. 6,4) as "Nautilus lallieri
d'Orbigny" has suture line trending straight or
with an adoral bow on the venter; the venter on
the latter species is flat to weakly excavated
with bicarinate margins and with maturity a cen·
tral carina begins to develop, but this trait is
not observed on Durham's species.

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 105
SUMMARY
-- · · ..
.. J_:· ·
In two regions of the Eastern Cordillera
of Colombia, namely Villa de Leiva and Apulo,
the lithologic sequences were ascertained and
carefully mapped. The ammonites collected bed
by bed from the lithologic sequences were taxo.nomically
investigated and this study constitu·.
tes the body of the present report.
102 species of ammonite.s are described
and illustrated, of these 8f11o of them are recognized
as new taxa; 52 g_eneral of ammonites are
described of which 21 u;o of the total is reported
new as follows: Colomboceratoides n. sg. [type
species Toxoceratoides (Colomboceratoides)
renzoni n. sp.J; Pseudoptychoceras n.g. (type
species Pseudoptychoceras gilberti n. sp. ]; Carloscaceresiceras
n.g. [type species Car/oscaceresiceras
caceresi n. sp.]; Corteziceras n. g. (type
species Co rteziceras cortezi n. sp. ]; Jaumaportai
ceras n. sg. [ type species Trochle!Ceras (Jaumaportaiceras)ho{{stetteri
n. sp.]; Zambranoites n.
sg. [type species Ve ctisites (Zambranoites)
zamoranoi n. sp.]; Juandurhamiceras n.g. (type
species Juandurhamiceras juandurhami n. sp.];
Stoyanowiceras n.g. (type species Ammonites
tre{fryanw; Karsten, 1858]; Riedelites n.g.
f type species Riede lites esthersemae n. sp. j;
'Rinconiceras n.g. f type species Rinconiceras
rinconi n. sp. ]; Ralphimlayites n.g. [type species
Acanthoceras prorsocurvatum Gerhardt, 1898];
Codazziceras n. g. [type species Lyelliceras
scheibei Riedel, 1938]; Franciscoites n. g. [type
species Ammonites toroanus Karsten, 1858];
Gloriaceras ng. [type species Gloriaceras correai
n. sp.l; Buenoceras n. g. [type species Buenoceros
loooi n. sp. ].
._ . ... ,,
The new species described are the following:
Holcophylloceras hemandezi n. sp., Hypophylloceras
wiedmanni n. sp., Eogaudryceras
helmsi, n. sp., Eogaudryceras (Eotetragonites)
cabaricoi n. sp., Toxoceratoides (Colomboceratoides)
renzoni n. sp., Pseudoptychoceras
gilberti n. sp., Aconeceras gutierrezpalmae n. sp.,
Me lchiorites palmeri n. sp., Valdedorsella (?)
rolombiam n.sp., Pseudohaploceras Ieiuaeme n.sp.
Carloscaceresiceras caceresi n. sp., Carloscaceresiceras
monteroi n. sp., Corteziceras cortezi n.
sp., Pse"(ldosayne/la ralphimlayi n. sp., Lewesiceras
(?) ulloai n. sp., Trochleiceras (Trochleice-.
ras) juliuerti n. sp., Trochleiceras (Jaumaportmceras)
ho{fstetteri n. sp., Cheloniceras (Epiche·
loniceras) dognaeluirae n. sp., Cheloniceras
(Epich eloniceras) camachoi n. sp., Cheloniceras
(Epicheloniceras) carlosacostai n. sp., Cheloniceras
(Ep icheloniceras) jimenoi n. sp., Cheloni·
ceras (Epicheloniceras) ban:eroi n. sp., Cheloniceras
(Epich eloniceras) pardoi n. sp., Cheloni:
ceras (Epicheloniceras) leonhardtriedeli n. sp.,
Cheloniceras (Epicheloniceras) huertasi n. sp.,
Vectlsites (Zambranoites) zambranoi n. sp.,
Vectisites (Zambranoites) cruzi n. sp., Ve ctisites
(Zambranoites) mateusi n. sp., Ve ctisites
(Zambranoites) cadenai n. sp., Vectisites
(Zambranoites) duquesi n. sp., Hypacanthopli­
es (?) dognaliciae n.sp., Juadurhaf1!icer!V!
Juandurhami n. sp., Juandurham1ceras gzrald01
·: ".i; .. ' ,
n. sp., Acanthohoplites bigoureti(orin.e n. sp.,
Acanthohoplites seunesiforme n. sp., Acanthohoplites
quitasuegno n. sp., Acanthohoplites
odiosus n. sp., Acanthohoplites pluricostatum
n. sp., Acanthohoplites elegan tean te n. sp.,
Acanthohoplites luisperezi n. sp., Acanthohoplites
(?) lep tocerati{orme n.sp., Acarrtf!.fiOplites
(?) serpenti{orme n. sp., Colombiceras {? ) foreroi
n. sp., Colombiceras (?) sarmientoi n. sp.,
• Gargasiceras (?) juanwyatti n. sp., Douvilleiceras
tarapacaense n. sp., Douvilleiceras abozagloi n.
sp., Eodouvilleiceras pedrocarvajali n. sp., Eodouvilleiceras
(?) tequendamai n. sp., Du{renoyia
boteroi n. sp., Du{renoyia hansbuergli n. sp.,
Ne odeshayesites albertoalvarezi n. sp., Neodeshayesites
ciPgulatum n. sp., Stoyanowiceras
cin tatum n .. sp. , Riedelites esthersernae n. sp.,
Riedelites quebradanegra n. sp., Riedelites
{ilosum n. sp., . Parahoplites hubachi n. sp.,
Parahoplites triston n. sp., Engonoceras olgaluciae
n. sp., Engonoceras (?) duartei n. sp.,
Platiknemiceras colombiana n. sp., Knemiceras
pegnai n. sp., Rinconiceras rinconi n. sp.,
Lyelliceras carvaja/orum n. sp., Lyelliceras
pseudolyelliforme n.sp., Lyelliceras isaacleaz· n.
sp., Ralphimlayites apuloense n. sp., Tegoceras
benauidescaceresi n. sp., Codazziceras {ina n.
sp., Mammites nodosoidesappelatus n. sp.,
Mammites {ugax n. sp., Mamites scutulatus n.
sp., Franciscoites suarezi n. sp., Im/ay{ceras (?)
ralphimlayi n. sp. Fagesia zanellai n.>sp., Paramammites
colombianus n. sp., Hoplitoides
hernanmojicae n. sp., Hoplitoides lacabagnae
n.sp., Hoplitoides lagiraldae n. sp., Niceforoceras
boyacaense n. sp., Peroniceras robertogarciae
Peroniceras diabloi n. sp., Peroniceras guerrai n.
sp., Prionocycloceras portarum n.sp., Prionocycloceras
(?) cucaitaense n. sp., Gloriaceras correai
n. sp., Gloriaceras paulinae n. sp., Zumpangoceras
ospinae n. sp., Zumpangoceras (?)
sorae n. sp., Buenoceras loboi n. sp., Protexani·
tes cucaitaense n. sp.
These different species of ammonites represent
a biostratigraphic sequence ranging in age
from Upper Aptian to Lower Santonian, based on
them, tb> following zonation ("Assemblage-zone"),
has been proposed: 1) Zone of Du{renoyia sanctorum
and Stoyanowiceras tre{{ryanus, below;
2) Zone of Parahoplites (?) hubachi and Acanthohoplites
(?) leptoceratiforme, above for the
Upper Aptian; 3) Zone of Neodeshayesites columbianus
and Douuille iceras solitae for the
Lower Albian; 4) Zone of Pla tiknemiceras colombiana,
Rinconiceras rinconi and Lyelliceras
pseudolyelli{orme for the Middle Albian; 5)
Zone of Mammites nodosoidesappelatus and
Franciscoites suarezi for the Lower Turonian;
6) Zones of Gioriaceras correai, Pro texanites cu·
caitaense and Codazziceras scheibei for the
Lower Coniacian; 7) Zone of Lenticeras baltai
and Paralenticeras sieuersi for the Lower Santo·
nian.
Assemblages representing the Upper Albian,
Cenomanian, Upper Turonian, and Upper
Coniacian were not recognized. Detailed descrip·
tions of some lithostratigraphic units are given,
ar;.d their faunal content indicated.

106 F. ETA YO · SERNA
En dos regiones de Ia Cordillera Oriental
de Colombia, en Villa de Leiva y Apulo, se determinaron
las secuencias litol6gicas que fueron
cludadosamente cartografiadas. Las amonitas
colectadas estrato por estrato de tales secuencias
litologicas fueron taxon6micamente investigadas
y este estudio constituye el objetivo
principal de este escrito.
Se describen e ilu!l;ran 102 especies de
amonitas, de las cuales ssu;a::onfonnan nuevas taxa;
se deben 52 generos de amonitas de las
cuales 2lu/odel total se dictaminan como nuevas
asi: Colomboceratoides n. sg. [especie tipo Toxoceratoides
(Colomboceratoides) renzoni n.
sp. ]; PseudoptychocerO$ n. g. [ especie tipo Pseudoptychocer:O$
gilberti n. sp. ]; CarloscaceresicerO$
n. g.f,especie tipo Carloscaceresiceras caceresi
n. sp. ; Corteziceras n. g. [especie tipo Corteziceras
cortezi n. sp. ]; Jaumaportaicer(l$ n. sg.,
r especie tipo Trochleiceras (JaumaportaicerO$)
hof{stetteri n. .J;Zambranoites n. sg. [especie
tipo Vectisites (Zambranoites) za.mbranoi n. sp. ];
Juandurhamiceras n. g. [especie tipo Juandurhamiceras
juandurhami n. sp.]; StoyanowicerO$ n.
g. respecie tipo Ammonites treffryanw Karsten,
18158 J; Riedelites n. g. [ especie tipo Riedelites
esthersemae n. sp. J; Rinconiceras n. g. r especie
tipo RinconicerO$ rinconi n. sp. ]; Ralphimlayites
n. g. respecie tipoAcanthocerasprorsocurua·
tum· G!:!rfiardt, 1898]; Codazziceras n. g. [ espe

ZONATION OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 107
Les sequences lithologiques des regions de
Villa de Leiva et de Apulo, dans la Cordillere
Orientale de Colombie, cartographb!es en detail
ont ete detenninees. Les ammopites, recueillies
strate par strate ont ete clllll.Wes taxonom
ment; cette etude constitue l'objectif du present
travail.
102 especes d'ammonites sont decrites et
illustrees, parmi lesquelles 85 o/o confonnent un
nouveau taxon; 52 genres d'ammonites sont
decrits panni lesquels les 21% suivants sont
considerees comme nouveaux: Co lomboceratoides
n. sg. respece type Toxoceratoides (Colomboceratoicfes)
renzoni n.sp.];Pseudoptychoceros
n. g. f espeee type Pseudoptychoceras gilberti n.
sp.j; Carloscaceresiceras n. g. [espece type Carloscaceresiceras
caceresi n.sp. ]; Corteziceras n.g.
[qspeee type Co rteziceras cortezi n.sp.J; Jaumaportaiceros
n. sg. r espeee type Trochleiceras
(Jaumaportaiceros) hof{stetteri n.sp.l; Za mbranoites
n. sp. [espeee type Ve ctisites (Zambranoites)
zambranoi n. sp.j; Juandurhamiceras n. g.
[espece type Juandurhamiceras juandurhami
n. sp.];Stoyanowiceras n.g. respece type Ammonites
tref{ryanus Karsten 1S58]; Riedelites n.a.
respece type Riedelites esthersemae n. sp.1;
1linconiceros n.g. r espece type Rinconiceras rinconi
n.sp. ]; Ralp'himlayites n.g. [ espece type
Acanthoceras prorsocurvatum Gerhardt, 1898};
Codazziceras n.g. [espeee type Lyelliceras schezbei
Riedel, 1938]; Franciscoites n. g. [espece type
Ammonites toroanus Karsten, 1858]; Gloriaceras
n.g. [ espece type Gloriaceras correai n.sp. ];
Buenoceras n.g. [ espece' type Buenoceras lo boi
n.sp.].
Les nouvelles especes decrites sont les suivantes:
Holcophylloceras hemandezi n. sp., Hypophylloceras
wiedmanni n. sp., Eogaudryceras
helmsi n.sp., Eogaudryceras (Eotetragonites) cabaricoi
n.sp., Toxoceratoides (Colomboceratoides)
renzoni n.sp., Pseudoptychoceras gilberti
n.sp., Aconeceras gutierrezpalmae n.sp., Me lchiorites
palmeri n.sp., Valdedorsella (?) colombiana
n.sp., Pseudohaploceras leivaense n.sp., Carloscaceresiceros
caceresi n.sp., Carloscaceresiceras
monteroi n.sp., Corteziceras cortezi n.sp.,
Pseudosaynel/a ralphimlayi. n.sp., Lewesiceras (?)
ulloai n.sp., Tro chleiceras (Trochleiceras) juliuerti
n. sp., Trochleiceras (Jaumaportaiceras)
hof{stetteri n.sp., Cheloniceras (Epicheloriiceras)
camachoi n.sp., Cheloniceras (Epicheloniceras)
carlosacostai n.sp., Cheloniceras (Epicheloniceras)
jimenoi n. sp., Cheloniceras (Epicheloniceras)
barreroi n. sp., Cheloniceras (Epicheloniceras)
pardoi n. sp., Cheloniceras (Epicheloniceras)
leonhardtriedeli n.sp., Cheloniceras (Epicheloniceras)
huertasi n.sp., Vectisites (Zambranoites)
zambranoi n. sp., Vectisites (Zambranoites) cruzi
n.sp., Vectisites (Zambranoites) mateusi n.sp.,
Vectisites (Zambranoites) cadenai n. sp., Ve ctisites
(Zambranoites) duquesi n. sp., Hypacanthoplites
(?) dognaliciae n.sp., Juandurhamiceras
juandurhami n.sp., Juandurhamiceras giraldoi
n.sp., Acanthohoplites bigoureti{orme n . .:p.,
RESUME
Acanthohoplites teunuiforme n. sp., Acanthohoplltu
quitasuegno n. sp., ACtJnthohoplitu
odiosru n. up., Acanthohoplites pluricostatum
n. sp.,Acanthohoplites eleganteante n. sp.,ACtJn·
thohoplites luisperezi n. sp., Acanthoh¢plitu
(?) leptocerotlforme n. sp., Acanthohoolites (?)
• serpenti{orme n. ap., Colombiceras (?) foreroi
n. sp., Colombiceras (?) sarmientoi n. sp., Gargasiceras
(?) juanw.vatti n. sp., Douvilleiceras
tDrapacaense n. ap., Douvilleiceras abozagloi n.
aD., Eodouvilleicel'dll pedroCtJrvajali n. sn., Eodouuilleiceras
(?) tequendamai n. sp., DutrenoyilJ
boteroi n. sp., DutrenoyilJ hansbuergli n. ap.,
Ne odeshayesites albertoalvarezi n. sp., Neoduhayesites
cingulatum n. ap., Stoyanowiceras
cintatum n. so., Riedelites esthersemae n. sp.,
Riedelites quebrodaneea n. sp., [liedelites filasum
n. sp., Parohoplites hubachi n. ap., Parahoplites
tristan n. s. t Engonoceros o[Haluciae n.
so., Engonoceras (? J duartei n. sp., Platiknemiceros
colombiana n. sp., Knemiceras pegru,i n.
sp., Rinconiceras rin coni n. sp., LyP-llicera8 carvaialorom
n. sp., Lyelliceras pseudoljelli{orme
n. sp., Lyelliceras isCUJcleai n. sp., Ralphimlayites
apuloense n. ap., Tegoceras ·benavldescaceresi.
n. sp., Codazziceras {ina n. sp., Mammites nodosoidesappelatus
n. sp., Mammites {ugax n. sp.,
Mammites scutulatus n.sp.,Franciscoites suarezi
n. sp. Imlayiceras (?) rolphimlayi n. sp., FagesilJ
zanet'fui n. sp.,Paramammites colombilJnus n. sp.,
Hoplitoides hemanmojicae n. sp., Hoplitoides
lacabagnae n. sp., Hoplitoides lagiraldae n.
ap., Nice{oroceras boyacaense n. sp.,Peroniceras
robertogarcwe n. sp., Peroniceras diabloi n. sp.,
Peroniceras guerrai n.sp.,friono.cycloceras por­
tarom n. sp., Prionocycloceras (?) cucaitaense
n. sp., Gloriaceras correai n. sp., Gloriaceras pau·
linae n. sp., Zumpangoceras ospinae n. sp., Zumpangoceras
(?) sorae n. sp., Buenoceras loboi n.
sp., Protexanites cucaitaense n. sp.,
Ces especes differenms d'ammonites representant
une sequence bio stratigraphique dont
l'ige s'etend de 1' Aptien Superieur jusqti' au Santonien
Inferleur. On pro r. ose pour 12t intervafie
Ia zo'lation suivante: ('mblage-zone;"), 1)
Zone de Du{renoyia sanctorom et Stoyanowiceras
tref{ryanus sous Ia; 2) Zone de Parahoplites
(?) hubachi et Acanthohoplites (?) lep toceratiforme
au dessus de I' Aptien Superieur; 3) Zone
de Neodeshayesites columbianus et Douvilleiceros
solitae pour 1' Albien Inferieur; 4) Zone de
Platiknemiceras colombiana, Rinconzceras rinconi
et Lyelliceras pseudolyelli{orme pour 1' Albien
Moyen; 5) Zone de Mammites nodosoidesappelo.tus
et Franciscoites suarezi pour le Tou·
ronien Inferieur; 6) Zone de Gloriaceras correai,
Protexanites cuca1taense et Codazziceras scheibei
pour le Coniacien inferieur; 7) Zone de Lenticeras
baltai et Paralenticeras sieversi pour le
Santonien lnferieur. Les Ammonites representatives
de l' Albien Superieur. du cenomanien, du
Turonien Superieur et du Coniacien Superieur
n'ontpas ete identifiees.Ce travail conUent flnale
ment Ia description detaillee de quelques unites
lithologiques ainsi que Ia faune qu'elles contiennent.

108
In due regioni della Cordigliera Orientale
di Colombia, Villa de Leiva e Apulo si sono
stabilite alcune sequenze litologiche rilevate poi
con cura. Le ammoniti, raccolte strato a strato
secondo l'ordine della successione litologica,
sono state oggetto della ricerca tassonomica che
viene presentata in questo scritto.
Si descrivono e illustrano 102 specie di
ammoniti, fra le cuali 85o/osi assegnano a novi
taxai si descrivono 52 generi di ammoniti fra le
quali l'autore e del parere che 2lo/osiano nuovi:
Colomboceratoides n. sg. J specie tipo Toxoceratoides
(Colombocerato · es) renzoni n. sp. ];
Pseudoptychoceras n. g. [species tipo Pseudoptychoceras
gilberti n. sp.1; Carloscaceresiceras
n. g. f specie tipo Carloscaceresiceras caceresi n.
sp.j; torteziceras n. g. [specie tipo Corteziceras
cortezi n. sg. J; Jaumaportaiceras n. sg. r specie
tipo Trochleiceras (Jaumaportaiceras) hoffs tetteri
n. sp. J; Zambranoites n. sg. [specie tipo Vectisites
(Zambranoites) zambranoi n. sp.l; Juandurhamiceras
n. g. [species tipo lllllndurhamicems.juandurhami
n.sp.J;Stoyanowiceras n.g. [spe·
cie tipo Ammonites tre{fryanus Karsten 1858];
Riedelites n. g. [specie tipo Riedelites estherser­
nae n. sp. ]; Rir,coniceras n. g. [specie tipo Rin­
coniceras rinconi n. sp. ]; Ralphimlayites n. g.
fspecie tipo Acanthoceras prorsocurvatum Ger­
hardt, 1898 ]; Codazziceras n. g. f specie tipo
Lyelliceras scheibei Riedel, 1938 j; F'ranciscoites
n. g.
J specie
tipo A.mmonites toroanus Karsten,
1858 ; Glorillcera n. g. [specie tipo Gloriaceras
correai n. sp.]Buenoceras n. g. [specie tipoBue­
noceras loboi : . sp. ].
. . · Le nuve specie. descritte sono Je seguenti:
Ho lcophylloceras hemandezi n. sp.Hypophyllo•
ceras wiedmanni n. sp., Eogaudryceras helmsi
n. sp., Eogaudryceras (Eo tetragonites) cabaricoi
n. sp., Toxoceratoides (Colomboceratoides) ren­
zoni n. sp., · Psudoptychoceras gilberti n. sp.
Aconeceras gut1errezpalmae n. sp. Melchiorites
palmeri n.sp., Va ldedorsel/a (?) colombiana n.sp.
Pseudohaploceras leivaense n. sp., Carloscaceresiceras
caceresi n. sp., Carloscaceresiceras monteroi
n. sp., Corteziceras cortezi n.sp., Pseudosoynella
ralphimlayi n.sp., Lewenceras (?) ulloai
n.sp., Trochleiceras (Tt'ochleiceras) juliverti n.sp.,
Trochleiceras (Jaumavortaiceras l hnff.tP.tteri n.
sp., Cheloniceras (Epicheloniceras) dognaetVIrae
n. sp., Cheloniceras (Epicheloniceras) camachoi
n. sp. Cheloniceras (Epicheloniceras) carlosacos­
tai n.' sp., Cheloniceras (Epicheloniceras) jime­
noi n. sp., Cheloniceras (Epicheloniceros) ba"e­
roi n. sp., Cheloniceras (Epicheloniceras) pardoi
n. sp., Cheloniceras (Epicheloniceras) ieonhar­
dtriedeli n. sp., Cheloidceras (Epichelonbras)
huertasi n. sp., Vectj$ites (Za mbranoites) zam­
branoi n. sp., Vecti&jJ{Is .. (ambranQ.ites) ,cruzi
n. sp., Vectisites (Za.iJiP-[4ttoite$) mateust n. sp.,
Vectisites (Zambraii0MI1); cadenai n; sp., Vec­
tisites (Zambranoites) duquesi n. sp., Hypacan·
thoplites (?) dognaliciae n. sp., Juandurhcmice­
ras juandurhami n. sp., Juandurhamiceras giral­
doi n.sp., Acantholwplites bigourctiforme n. sp.;
F. ETAYO ·SERNA
RIASSUNTO
Acanthohoplites seunesiforme · n. sp., Acanthohoplites
quitasuegno n. sp., Acanthohoplites
odiosus n. sp., Acanthohoplites pluricosta tum
n. sp.,Acan thohoplites eleganteante n. sp.,Acanthohoplites
luisperezi n. sp., Acanthohoplites
(?) leptoceratiforme n. sp., Acanthohoplites (?)
serpenti{orme n. sp., Colombiceras (?) foreroi
n. sp., Colombiceras (?) sarmientoi n.sp., Gargasiceras
(?) juanwyatti n. sp., Douuilleiceras tarapacaerise
n. sp., Douuilleiceras abozagloi n. sp.,
Eodouvilleiceras pedrocarvajali n. sp., Eodouvilleiceras
(?) tequendamai n. sp., Du{renoyia
boteroi n. sp., Du{renoyia hansbuergli n. sp.,
Neodeshayesites albertoalvarezi n. sp., Neodes·
hayesites cingulatum n. sp., Stoyanowiceras
cintatum n. sp., Riedelites esthersemae n. sp.,
Riedelites quebradanegra n. sp., Riedelites {flosum
n. sp. Parahoplites hubachi n. sp., Parahoplites
t,.iston n. sp., Engonoceras olgaluciae n. sp.,
Engonoceras (?} duartei n. sp., Platiknemiceras
colombiana n. sp., Knemiceras pegnai n. sp.,
Rinconiceras rinconi n. sp., Lyelliccras carvajalorum
n. sp.,Lyelliceras pseudolyelli{orme n.sp.,
Lyellieceras isaacleai n. sp., Ralphimlayites
apuloense n. sp., Tegoceras benavidescaceresf
n. sp., Codazziceras {ina n. sp., Mammites nodosoidesappelatus
n. sp., Mammites {ugax n. sp.,
Mammites scutulatus n. sp. ,Fhnciscoites suarezi
n. sp., Imlayiceras (?) ralphimlayi n. sp., Fagesia
zanellai n. sp., Paramammites colombianus n.sp.,
Hoplitoides hemanmojicae n. sp., Hoplitoides
lacabagnae n. sp., Hoplitoides lagiraldae n. sp.,
Nice{oroceras boyacaense n. sp., Peroniceras robertogarciae
n. sp., Peroniceras diabloi n. sp.,
Peroniceras guerrai n. sp., Prionocycloceras portarum
n. sp., PrionocyclocerU$ (?) cucaitaense n.
sp., Glorillceras correai n. sp., Gloriaceras paulinae
n. sp., Zumpangoceras ospinae n. sp., Zum , ·
pangoceras (?} sorae n. sp., Buenoceras loboi n.
sp., Protexanites cucaitaense n. sp.,
ueste diverse specie di ammoniti rappre­
sentano una sequcnza biostratigrafica che si
stende in eta dall Aptiano Superiore fino al San·
toni?..no Inferiore dentro Ia quale l'autore pro·
pone la seguente zonificazione, \'Assemblage·
zone"): 1) Zona aDufrenOJiiz sanctorum y Sto­
yanowiceras treffryanus sottostante; 2) Zona a
Parahoplites- (?) hubachi y Acanthohoplites (?)
leptoceratiforme, soprastante (?) L'Aptiano Su­
periore; 3) Zona a Neodeshayesites columbianus
y Douvilleiceras solitae per I' Albiano Inferiore;
4) Zona a Platiknemiceras colombitzna, Rinconi­
ceras rinconi y Lyelliceras pseudolyelli(orme per
l' Albiano Medio; 5) Zona a Mammites nodosoi­
desappelatus y Franciscoites suarezi per il Turo­
niano Inferiore; 6) Zona a Glorillceras correai,
Protexanites -cucaitanse y Codazziceras scheibei
per il Coniaciano Inferiore; 7) Zona a Lentice­
ras baltai y of?aralenticeras sieversi per il Santo.- '
niano· Inferio,:Q .. -Non si sono riconosciute le fau·. ·
ne reopresentiltive dell' Albiano Superiore, del
Cenoina:1iano, Turoniano Superiore e Coniacia·
no Superiom.
Si descrivono minuziosamente alcune unita
litostratigrafiche e si indica Ia fauna I( conteta.

ZONA "nON OF THE CRETACEOUS OF CENTRAL COLOMBIA BY AMMONITES 109
In den Umgebungen von Villa de Leiva und
Apulo, zwei Gebieten auf der Ostlichen Kordillere
Kolumbiens, wurden die lithologischen Abfolgen
der Kre,de aufgJ)nommen und sorgf3Itig Kartographiert.
Die aus jeder Schich_t aufgesammenlten
Anmoniten wurden taxonomisch untersucht.
Die Ergebnisse dieser Untersuchung stellen das
Hauptziel der vorliegenden Arbeit dar.
Es werden 102 Ammoniten-Arten beschrie_
ben und abgebildet, aarunter 85 o/oDeueTaxa. Es
werden auch 52 Ammoniten-Gattungen beschrieben,
unter denen sich 21 %neue Gattungen
finden : (Colomboceratoides) n. sg. [Typus Art
TgxoceratoitJes (Colomboceratoides) renzoni.
n sp.]; Pseudoptychoceras n. sg. (Typus Art
Pseudoptychoceras gilberti n. sp· ]; Carloscaceresiceras
n. g. (Typus Art Carloscaceresiceras
caceresi n. sp.J; Cortezicer{ls n. g. (Typus Art
C.,o rteziceras cortezi n. sp. ]; JauTTUJportaiceras
n. sg. fTypus Art Trochleiceras (Jaumaportaiceras)
hof{stetteri n. sp .] ; Zambranoites n.sg.
(Typus Art Ve ctisites (Zambranoites) zambranoi
n. sp.] ; Juandurhamiceras n. g. [Typus Art
Juandurhamiceras juandurhami n. sp.]; Stpyanowiceras
n. g. fTypus Art Ammonites treffryanus
Karsten 18581; Riedelites n. g. (Typus Art
Riedelites esthersemae n. sp.]; Rmconiceras
n. g. [ Typus Art Rinconiceras ri11coni n. sp.];
Ralphimlayites n. g. {Typus Art Acanthoceras
prorsocurvatum Gerhardt 1898]; Codazziceras
n. g. (Typus Art Lyelliceras scheibei Riedel,
1938]; Franciscoites n. g. fTypus Art Ammonites
toroanus Karsten 185S]; Gloriaceras n. g.
[Typus Art Gloriaceras correai n. sp.]; Buenoceras
n. g. (Typus Art Buenoceras Ioboi n. sp.
Bei den neun aufgestellten arten handelt es
sich urn: Holcophylloceras hemandezi n. sp.,
Hypophylloceras wiedmanni n. sp., Eogaudryceras
helmsi n. sp., Eogaudryceras (Eotetragonites)
cabaricoi n. sp., Toxoceratoides (Colo mbocera
toides) renzoni n. sp., Pseudoptychoceras
gilberti n. sp., A coneceras gu tierrezpalmae n. sp.,
Melchioritespalmeri n. sp., Va ldedorsella (?) colombiana
n. sp., Pseudohaploceras leiuaense n.
sp., Carloscaceresiceras caceresi n. sp., Carloscaceresiceras
monteroi n. sp., Corteziceras cortezi
n. sp., Pseudosaynella ralphimlayi n. sp., Lewesiceras
(?) ulloai n. sp., Trochleiceras (Trochleiceras)
.juliuerti n. · sp., Trochleiceras (Jaumaportaiceras)
ho((stetteri n. sp., Cheloniceras (Epicheloniceras)
camachoi n. sp., Cheloniceras
(Epicheloniceras) carlosacostai n. sp., Cheloniceras
(Epicheloniceras) jimenoi n. sp., Cheloniceras
(Epicheloniceras) barreroi n. sp., Cheloniceras
(Epicheloniceras) Pflrdoi n. sp., Chelonice·
ras (Epicheloniceras) leonhatdtriedeli n.sp, Chelniceras
(Epiche/oniceras) huertasi n. sp., Vecttliltes
(Zambranoites) zambranoi n. sp.,Vectisi·
tes (Zambranoites) cruzi n. sp., Ve ctisites (Zambra
. noites) mateusi n. sp., Vectisites (Zambranoltes)
cadenai n. sp., Ve ctisites (Zambranites)
duquesi n. sp., Hypacanthoplites (?) dognaliciae
n. sp., Juandurhamiceras juandurhami n. sp.,
Juandurhamiceras giraldoi n. sp.,Acanthohoplites
bigoure ti{orme n. sp., Acanthohoplites
seunesiforme n. sp., Acanthohoplites qui-
ZUSAQENF ASSUNG
·· ; .( : . {[,;£>
·
..._ : ·
tasuegno n. sp., Acanthohoplites odiosus n. sp.,
Acanthohoplites pluricostatum n. sp., Acanthohoplites
eleganteante n. sp., Acanthohoplites
luisperezi n. sp., Acan thohoplites (?) leptocerati{orme
n. sp.,Acanthohoplites (?)serpenti{onne
n. sp., Colombiceras (?) (oreroi n. sp., Colombiceras
(?) sarmientoi n. sp:;Bargasiceras (?) juanwyatti
n. sp., Douuilleiceras tarapacaense n. sp.,
Douvilleiceras abozagloi n. sp., Eodouuilleiceras
pedrocarvajali n. sp.,Eodouuilleiceras (?) tequendamai
n. sp., Dufrenoyia boteroi n. sp., Du(renoyia
hansbuergli n. sp., Neodeshayesites albertoalvarezi
n. sp., Neodeshayesites cingulatum n.
sp., Stoyanowiceras cintatum n. sp., Riedelites
quebradanegra n. sp., Riedelites filos., n. sp.,
Parahoplites hubachi n. sp., Parahoplites tristan
n. sp., Engonoceras olgaluciae n. sp., Engonoceras
(?) duartei n. sp., Platiknemiceras colombiana
n. sp., Knemiceras pegnai n. sp., Rinconiceras
rinconi n. sp., Lyelliceras caru

110
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ZONATION OF THE CRETACEOUS OJI' CENTRAL COLOMBIA BY AMMONITES 111
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·.
FIGURES 3-17

120
A)
B)
C)
D)
E)
F)
G)
H)
I)
L)
M)
N)
0)
Terminology utilized in this paper when
describing whorl sections; M vl: median
ventral line AV: adventral: M: middle;
AU: adumbilical.
Terminlogy utilized in describing the ribs;
Ao: adoral; Aa: adapical; Cc: concavity;
Bp: branching point; Cv: convexity ; Pr:
proyection.
Whorl section of Phylloceras buchianum
forbes); C-217. a) hypotype at a whorl
height (=H.) of 3 mm (x 5 2/3); b) hypotype
at H:6 mm (x 5 2/3).
Growth striae and constriction ridge profile
of Holcophylloceras hemandezi n.sp.,
holotype C-13 at H: 8 mm (x 1 5/8).
Rib profile of Hypophylloceras wiedmanni
n.sp. \ holotype C-225, at H: 14
mm (x 1 1/3J.
Terminology utilized in this work descri·
bing the elements of the suture line: E:
external lobe; L: lateral lobe; U: umbilical
lobe, 1: internal lobe. E/L: seddle between
; E and L lobes.
Types of ribbing described in this work.
Whorl section of Holcophylloceras hernandezi
n. sp., holotype C-13, at H: 8 mm
(x 2 6/8).
External suture line of Holcophylloceras
hernandezi n. sp., holotype C-13, at H: _
8 nim (x 2 6/8).
Whorl section of Eogaudryceras helmsi
n. sp., holotype C-223, a) at H : 4 mm
(x 1 1/2); b) at H :14 mm (x 1 1/2).
Whorl section of Eogaudryceras (Eo tetragonites)
cabaricoi n. sp., holotype C-513,
at H: 14mm (x 1 1/2).
Part of external suture line showing L, of
Eogaudryceras (Eote tragonites} cabaricoi
- n. sp., holotype at H: 8mm (x 1 1/2).
Whorl section of Toxoceratoides (Colombocera
toides)renzoni n. sp., holotype LB·
F. ETA YO · SERNA
FIGURE 3
P)
Q)
R)
S)
T)
U)
V)
W)
X)
Y)
Z)
$)
fi)
10. a) at H: 9.5 mm (x 28/9); b) at H: 3.5
mm (x 2 8/9).
Complete suture line of Toxocera toides
(Colomboceratoides) renzoni n.sp.,morph
I, C-220, at H: 5 mm.
Whorl section of Me lchioriles media Riedel,
hype type C-127, at H: 6mm (x 3 1/6).
External suture line of Melchioriles media
Riedel, hypotype C-127, at H: 6 mm
(x 2 1/6).
Whorl section of Pseudoptychoceras gilberti
n. sp., holotype C-223, at H:5 mm
(x 3).
Complete last suture line of Pseudoplychoceras
gilberti n. sp., paratype C· 223,
at H: 6 mm (x 3).
Whorl section of Pseudohaploceras leiuaense
n. sp., holotype VL-10-17, at H:
19.5 mm (x 1 1/2).
Profile of the adoral ridge of a constriction
in Valdedorsella (?) colombiana n. sp,
paratype Sta Ana, at H: 12 mm (x 1 1/4).
Whorl section of Valdedorse/la (?) colombiana
n. sp., paratype Sta. Ana, at H: 13
mm (x 1 1/5).
Whorl section of Aconeceras gu tierrezpalmae
n. sp., paratype C-223. a) at H: 3mm;
b) at H: 5.5mm (x 6).
_Part Qf external suture.line of Aconeceras
gulierrezpalmae n. sp., holotype C-223 at
H: 8mm.
Profile of a growth striae of Aconeceras
gutierrezpalmae n. sp., holotype C-223,
at H: 8mm (x 2 7/8).
Whorl section of Melchiorites palmeri
n. sp., holotype C-223, at H: 6mm (x 2 1/3)
Whorl section of Corteziceras (?)n.sp.ind.,
C-5 13, at H: 14 mm (x 1 1/3).
External suture line of Pseudohaploceras
leiuaense n. sp. holotype at H: 13 mm.

122 . F. ETA YO · SERNA
A)
B)
C)
D)
E)
F).
G)
H)
I)
J)
K)
Whorl section of Carloscacercsiceras caceresi
n. sp., paratype C-13-27, at H:20mm
(x 1 1/2).
External suture line of Carloscaceresiceros
caceresi n.sp.,paratype C-13-37, atH:lBmm.
Whorl section of Corteziceras cortezi n.
sp., . Sta. Ana, holotype at H:20 mm
{x 1 1/2).
a) Whorl section of Lewesiceras (?) ulloai
n. sp., c-310, holotype, at H : 8 mm (x
1 1/2); b) profJle of the adapical ridge of
a constrictions, ib. at H : 9.5 (x 1 1/2).
External suture line of Carloscaceresiceras
monteroi n. sp., holotype C-13-33, at H.:
16 mm (x 1 1/2).
Whorl section of Corteziceras latecostata
(Riedel), hypotype C-225, at H : 21 mm
(x 1 1/2).
Whorl section of Trochleiceras (Jaumaportaiceras)
hoffstetteri n. sp., holotype
C-215-5, at H: 8mm (x 1 1/2).
Part of external suture line of Trochleiceras
(J.) ho{{stetteri n. sp., C-215, paratype,
at Ji: 5 mm.
Whorl section of Trochleiceras (Trochleiceras)
juliverti n. sp., holotype C-215-2,
at H:.4 mm (x 3).
·
. Whorl section of Carloscaceresiceras · (?)
chimuense (B.C.) n. sp.,h)lpotype VL-Est.
·
33a, at H: 34mm (x l l/7).
Part of external suture line of Carloscaceresiceras
('!) chimuense (B. C.) n.sp., holotype
VL-Est. 3aa, at H:18 mm (x 1 1/2).
L) Whorl; section of Trochleiceras (Jauma­
portiiiceras) hotfstetten· n. sp., C.215 para­
. type at H: 3 mm (x 3).
. '.: · ­
) . Part of external suture line of Trochleice·
ras (Trochleiceras) juliverti n. sp., C-215-1
· paratype,(x 3),·· ·
N) Whorl section of Pseudosaynella ralphim-
FIGURE 4
layi n. sp., paratYpe C-223x, at H:10 mm
(x 1 1/2).
0) External suture line of Pseudosaynella ralphimlayi
n. sp., holotype SV-28 at H:18
mm (x 1 1/2).
P) Whorl section of Cheloniceras (Epichelo·
niceras) barreroi n. sp., holotype C-514,
at H:17.5 (x 1 1/6).
Q)
R)
S)
T)
U)
V)
W)
X)
Y)
$)
Z)
External suture line of Cheloniceras (E)
barreroi n. sp., holotype C-514, at H: 9
mm (x 1 1/2).
Whorl section of Cheloniceras (Epicheloniceras)
carlosacostai n.sp., paratype
C-223-13, at H:19 mm (x 9/10).
External suture line of Cheloniceras (Epicheloniceras)
carlosacostai n. sp., holotype
C-223-16, at H:16.5 (x 1 1/2).
Whorl section of Cheloniceras (Epicheloniceras)
camachoi n.sp., holotype VL-10·
17, at H :21.5 mm (x 1 1/2).
Whorl section of Cheloniceras (Epicheloniceras)
leonhardtriedeli n. sp., C23, at
H:13.5 (x 1 1/3).
Whorl section of Cheloniceras (Epicheloniceras)
amazonarum (Burckhardt), bolo·
type C-514, at H:20mm (x 8/10).
Whorl section of Cheloniceras (Epicheloniceras)
dognaelvirae n. sp., holotype VL·
12-2, at H: 15 mm (x 1 1/5) .
Whorl section of Cheloniceras (Epicheloniceras)
jimenoi n. sp., holotype C-504,
at H:21 mm (x 4/5).
Whorl section of Cheloniceras (Epicheloniceras)
huertasi n. sp., paratype V17-Sa-
11, at H:11.5 mm (x 1 1/2).
Complete suture line of Ch. (E.) huertasi
n.sp., paratype VL7 SA-11, at H:6 mm
(x 1 1/2).
Whorl section of Cheloniceras (Epicheloniceras)
pardoi n. sp., holotype C-504, at
H: 22 mm (x 9/10).

124 F. ETA YO • SERNA
A)
B)
C)
D)
E)
F)
G)
H)
I)
J)
K)
L)
M)
Whorl section of Vectisites (Zambranoi·
tes) cruzi n. sp., holotype C-504, at H:10
mm (x 3).
External suture line of V. (Z. ) cruzi n.sp.,
holotype C-504, at H: 5 mm (x 3).
Whorl section of Juandurhamiceras juan·
durhami n. sp., paratype Santa Ana, at
H: 10 mm (x 2 8/10).
External suture line of Parahoplites (?) in·
constans Riedel?, C-501-13, at H: 8 mm
(x 1 1/2).
Whorl section ofGargasiceras (?) juanwya·
tti n. sp., holotype C-151, at H:11.5 mm
(x 1 1/2).
Part of the external suture line of Paraho·
plites hubachi n. sp., morph I, C-127, at
H: 13 mm (x 1 1/2).
External suture line of ParahopUtes tris·
ton n. sp., h.olotype C-127, at H: 6 mm
(x 3).
Whorl · section of Vectisites (Zambranoites)
zambranoi n. sp., holotype C-504, at
H:17.5 mm (x 1 1/2).
Whorl section of Ve ctisites (Zambranoites)
duquesi n. sp., paratype C-514, at H:
11 mm (x 1 11-2).
External suture line of Juandurhamiceras
juandurhami n. sp. Santa Ana-25, at H:13
mm (x 3).
External suture line of Vectisites (Zambranoites)
zambranoi n. sp., C-504, at
H: 12 mm (x 1 1/2).
Whorl section of Ve ctisites (Zambranoites)
cadenai n. sp., holotype C-514 at H:13
mm (x 1 1/2).
Whorl section of Du[renoyia boteroi n.sp.
holotype C-223 x-10, at H:20.5 mm (x 1
1/2).
N) External suture · line of Du[renoyia bo teroi
n. sp., holotype C·223x-10, at H:13
mm (x 1 1/2).
0) External suture line of Vectisites (Zambranoites)
zambranoi n. sp., holotype
C-504, at H:10 mm (x 1 1/2).
FIGURE 5
P)
Q)
R)
S)
T)
U)
V)
X)
Z)
iJ)
W)
Y)
u>
External suture line of Vectisites (Zam·
branoites) cadenai n. sp., holotype C-514,
at H:10 mm (x 1 1/2).
Whorl section of Aoanthohoplits seunesi·
forme n. sp., holotype C-127, at H:12
mm (x 1 1/2).
External suture line of Acanthohoplites
seunesi{orme n. sp., holotype C-127, at
H: 12 mm (x 1 1/2).
Whorl section of Acanthohoplites pluri·
costa tum n. sp., holotype C-127, at H:9
mm (x 3).
External suture line of Acanthohoplites
pluricostatum n. sp., holotype C-127, at
H: 9 mm (x 3).
Whorl section of Acanthohoplites bigoureti{orme
n. sp., holotype C-127, at H:
9 mm (x 1 1/2).
External suture line of Acanthohoplites
bigoureti[orme n. sp., bolo type C-127, at
H: 7 mm (x 3).
External suture line of Acanthohoplites
eleganteante n. sp., holotype C-127, at
H:6 mm (x 1 1/2).
Whorl section of Acanthohoplites quitasuegno
n. sp., holotype C-127, at H: 8
mm (x 3).
External suture line of Acan thohoplites
quitasuegno n. sp., holotype C-127, at H:
8 mm (x 3).
Whorl section of Acanthohoplites luisperezi
n. sp., paratype C-127, at H: 7 mm
(x 3).
External suture line of Acanthohoplites
luisperezi n. sp., paratype C-127, at H: 6
mm (x 3).
a) Whorl section of Acanthohoplites odious
n. sp., holotype C-127, at H:6 mm (x 1
1/2); b) ib. at H: 10 mm (x 1 1/2).
External suture line of A. odious n.sp.
holotype C-127 at H: 7 mm (x 3).
o) . Whorl section of Acanthohoplites {?) serpenti[orme
n. sp., holotype C-127 at H:
5mm(x5).
a) Whorl section of Acanthohoplltes (?) leptocerati[orme
n. sp., holotype ( x 5).

128
A)
B)
C)
D)
E)
F)
G)
H)
I)
Whorl section of Neodeshayesites cinf!u/atum
n. sp., holotype C-501·0, at H:30mm
(x 1 2/10).
Whorl section of Neodeshayesites contractu
(Riedel), hypotype C-500-3, at H:22
mm (x 1 1/2).
Superposed rib profiles of Neodeshayesi·
tes albertoaluarezi n. sp., at left of each·
figure; N. columbianus (Riedel) at center
of each figure, and N. karsteni (Marcou), the
profile transecting the other profiles except
on the first group of figures on the
left; the single profile (third from left to
right) corresponds to N. columbianus
(Riedel). From left to right at D:23mm,
D:37mm; D:42mm; H:21mm; H:26mm
(al X 1 1/2).
External suture line of Neodeshayesiles
contractu (Riedel), hypotype, C-500-4 at
H:25mm (x 11/2).
Rib profiles of N. contractu (Riedel), hypotype
C·500 (2), from left to right at
H:9mm; H:llmm; H:14mm; H:18mm,
(all X 1 1/2).
Rib branching in N. contractu {Riedel)
hypotype C-500 (2), at H:llmm {x 1 1/2).
External suture line of Neodeshayesites
cingula tum n. sp., holotypf' C-501-0, at
H:24mm (x 1 1/2).
External suture line of N. cingula tum n.sp.
paratype C-5.01-23,at H:14mm {x 1 1/2).
Rib profile of N. contracla (Riedel), after
fig; S .' .plate 7 of Riedel's paper (1937); at
· . ...
F. ETA YO - SERNA
FIGURE 7
K)
L)
M)
N)
0)
P)
Q)
R)
S)
T)
U)
H:11.5mm; H:13mm; H:14mm respectively
(X 1 1/2).
Rib profile of N. cingulatum n. sp., halotype
C-501-0, at H: 16mm (x 1 1/2).
Rib profile of N. cingula tum n. sp., halotype,
C-501·0, at H:22mm (x 1 1/2).
Whorl section of Sloyanowiceras lre{fry·
anus (Karsten), hypotype La Mesa 10 at
H:20mm (x 3).
External suture line of Stoyanowiceras
tref{ryanus {Karsten), hypetype La Mesa
10, at H:20mm (x 3).
Whorl section of Riedelites ('?) quebradanegra
n. sp., C -200 A, hypotype at H:16
mm (x 1 1/2).
Whorl section of Riedelites obliquum
(Riedel), C-5 14 (A), at H:16.5 (x 1 1/2).
Whorl section of Stoyanowiceras lre{{ryanus
(Karsten) after the original drawing
in Karsten (1858, pl.4 , fig.1b), (x 7 /9).
External suture of Riedelites ('?) quebradanegra
n. sp., Q·200 A, hypotype at H:
11.5mm (x 3).
External suture line of Riedeliles eslhersernae
n. sp., C-222A,holotype, at H:ll.5
mm (x 3).
Whorl section of Riedeliies esthersernae
n. sp., C · 222A, holotype , at H:16 mm
(x 1 1/2).
Whorl section of Riedelites {ilosum n. sp.
paratype C-225 (2), at H:16.5mm(x 1 1/2).

FIGURA 7
A
Q
8
) / !
E
I
c
K
FIGURE 7
p
i
· +
I
L

130
A)
B)
C)
D)
(.
. ..:;J
F)
G)
I)
K)
L)
M)
N)
0)
Whorl section of Platiknemiceras n. sp.A,
C-510 A, at H:Smm (x 3 ).
Part of external suture line of Engonoce·
ras olgaluciae n. sp., holotype C-510A, at
H :14mm (x 3).
Whorl section of Engonoceras olgaluciae
n. sp., holotype C-5 10A, at H:9mm
(x 1 2/10).
Part of external suture line of Knemiceras
pegnai n. sp., holotype C-131, at H:68
mm (lower suture) and H:85mm (upper
· ·
suture), (x 1).
Whorl section of Lyelliceras pseudolyelli·
forme s. sp., holotype C-255, at H:15mm
·
(x 2 1/10).
Whorl section of Knemiceras pegnai n. sp.
holotype C- 131, at H:89mm (x 1/4).
Whorl section of Knemiceras semicosla·
tum Sommermeier, hypotype, VL-Est.
33a. a) at H: 23 mm (x 1 1/2), b) at H:35
mm (x 1 2/10).
Whorl section of Lyelliceras carvajalorum
n. sp., holotype C-225, at H:16 mm (x 3).
External suture line of L. carvajalorum
n. sp.,paratype C-225, at H:17 mm (x 3).
External suture line of Pialiknemiceras
n. sp. A,C-5 10A, at H: 11 mm (x 3).
External suture line of Knemiceras semicostatum
Sommermeier, lectotype VL­
Est 33a, at H: 30 mm (x 1 2/10).
Whorf section of Codazziceras {ina n. sp.,
paratype C-134, at H:12 mm (x 1 1/2).
External suture line of Codazziceras {ina
n.sp.,paratype C-134, H:12 mm (x 1 1/2).
Whorl section of Mammites {ugax n. sp.,
holotype C-263, at H:14 mm (x 1 1/2).
F. ETA YO · SERN A
FIGURE 8
P)
Q)
R)
S)
T)
U)
V)
W)
X)
Y)
ii)
Whorl section of Mammites scutulatus n.
sp., holotype C-310, at H: 14 mm (x 1
1/2).
Whorl section of Codazziceras {ina n. sp.,
paratype C-134, at H:_4 mm (x 3).
Whorl section of Codazziceras scheibei n.
sp.,hypotype C-134, at H:13 mm (x 1 1/2).
Rib profiles of Codazziceras {ina n. sp.,
paratype C-134 and C. scheibe (Riedel),
hypotype C-134; figures to the right re·
present the ribs of latter. H 13 mm (x 1
1/2); long rib on right side at H:30 mm
(x 1 2/1 0).
....,
Whorl sections of Fagesia zanelli n. sp.,
paratype C-310, a) at H: 6mm; b) at H:15
mm, (both x 1 1/2).
Whorl sections of /mlayiceras (?) ralphim·
layi n. sp., paratype; a) at H: Groin (x 3);
b) at H: 24 mm (x 1 2/10).
Whorl section of Rinconiceras rinconi n.
sp., paratype C-169, at radius: 13 mm
(x 3).
External suture line of Rinconiceras rinconi
n. sp., holotype C- 169, at H: 8 mm
(x 4 5/10).
Whorl section of Franciscoiies suarezi ri.
sp., holotype C-310, at H: 14 mm (x 1
1/2).
External suture line of Franciscoites suarezi
n. sp., holotype C-310,at H: 13 mm
(x 3).
Part of external suture ( L) of Tegoce·
ras benavidescaceresi n. sp., holotype VL.
Est 33a, at H: 23 mm (x 1 2/10).
Part of external su ture of Tegoceras
benavidescaceresi n. sp., holotype VL.
Est. 33a, at H: 23 mm (x 1 2/10).
Whorl section of Franciscoites suaresi n.
sp., paratype C-310, at H: 4 mm (x 3).

132.
A)
B)
C)
D)
E)
F)
G)
H)
I)
J)
.
·.
F. ETA YO · SERNA
FIGURE 9
Whorl section of Peroniceras robertogar·
ciae n. sp., holotype VL 6 Cu-5, at H:13
mm (x 1 2/10).
Part of external suture line of Peroniceras
robertogarciae n. sp., holotype VL 6 CU·
5, at H:13 mm (x 1 1/2).
Whorl section of Gloriaceras correai n. sp.
holotype NRC·CA-1-5, at H:15 mm (x 1
1/2).
Rib profiles of Gloriaceras paulinae n.
sp., (on left side), and Gloriaceras correai
n. sp., (on right side), at H:ll mm and H:
22 mm respectively (x 1 1/2).
Whorl section of Peroniceras diabloi n.sp.
holotype NRC-3 at H:16 mm (x 1 1/2).
Rib profile of P. diabloi n. sp., holotype
NRC-3, at H: 16 mm (x 1 1/2).
External suture line of Peroniceras diabloi
n. sp., holotype NRC-1-5, at H:22 mm
9 :H (x 1 1/2).
External suture line of Gloriaceras correai
n. sp., holotype NRC -Est. 9, at H.: 22
(x 1 2/10).
Whorl section ofPeroniceras guerrai n. sp.,
holotype NRC-Est. 9, at H: 19 mm (x 1
1/2).
External suture line of Peroniceras guerrai
n. sp., holotype NRC-Est. 9, at H: 19 mm
(x 1 1/2).
Kt Whorl section of Gloriaceras paulinae n.
sp., paratype NRC-CU-5 ( x f1/2).
·
L)
M)
N)
0)
P)
Q)
R)
S)
T)
U)
V)
Last tlXi.emal suture line of Gloriaceras
paulinae n. sp., holotype NRC-CU-5.
Whorl section of Prionocycloceras (?)
cucaitaense n. sp., holotype at H:25mm
(X 1 2/10).
Whorl section of Prionocycloceras por·
tarum n. sp., holotype C-134, at H:20
mm (x 1 1/2).
Whorl section of Zumpangoceras ospinai
n. sp., holotype NRC-1, at H:22mm
(x 11/7). "
Whorl section of Zumpangodras ospinai
n. sp., paratype Sora NRC, at H;12mm
(X 1 2/10).
.
Whorl section of Protexanites cucaitaense
n. sp., holotype VL6-CU3 at H:17mm
(x 1 2/10).
External suture line of Buenoceras loboi
n. sp., holotype NRC-4 (1965), at H:25
mm (x 1 1/2).
Whorl section of Prionocycloceras ion·
gispinatum .(Basse), hypotype C-134,
at H:28mm (x 1 2/10).
Part of external suture line of P. longispinatum
(Basse), hypotype C-134, at
H:23mm (x 1 2/10).
Whorl section of Buenoceras loboi n. sp.,
holotype NRC-4 (1965) (x 1 1/2) .
External suture line of Hoplitoides hernanmojicae
n. sp., holotype C - 310, at
H: 26 mm (x 1 1/2).
·

FIGURA 9
e
M
s
!/
N
n
-l1Jrv?
r"'- •.
' · -
Q
T
• I
j
"
u
K
0
H
\
j
/
FIGURE ·9
l
0
p

134
Scatter diagram of the distribution of specimens
of Carloscaceresiceras carloscaceresi n.
sp. and Carloscaceresiceras monteroi n. sp., in
samples C-13, C-170 according to sizes. The
F. ETA YO · SERNA
FIGURE 10
relationships are between the external umbilical
width (=Euw) and the height of the whorl
(=H ). Small dots represent sample C-13; large
dots represent sample C-170.

FIGURA 10
3
. . -. ...
• •
•
: ...
-·
•
•• •
• • • • • •
•
•
•
• • •
• •• • •
• • •
• • •
•
• •
•
FIGURE 10
'. s '"------ -.- ---"--------H -r- w __________ "T""" ____ _
10 2 3
•
•
•

136
Scatter diagram of the relationships between
Euw and H ,. and the accompanying
variations in type and number of ribs in Chelo·
nicems (Epicheloniceras) carlosacostai n.. sp.,
NOTE: From fl&ure 11 to 17 the foUowtne •ymbols
wm be u.sed.
SYMBOLS
•
•
•
•
0
+
F. ETAY.O ·SERNA
FIGURE 11
type 88Dlple C-223. For the explanation of the
symbols used to repre11mt types of ribbing eee
figure 3G. .
No. OF RIBS
46 -50
41 · 45
36 .40
31 -35
26 -30
21 · 25
16 .20
11 -15

·FIGURA II
3
25
15
-- -
OD OD
10
O D
OD
o n
00D
OD
Hw
OD
OD'
20
OD'
0D
.
!'. FIGURE II
,., . .
30

138
Scatter diagram of the relationships between
Euw and H, and the accompanying
variation in type and number or ribs in Juan·
F. ETA YO · SERNA
FIGURE 12
durhamiceras jUtZndurhllrni n.sp., type ple
Santa Ana, A.P.G. .
v

FIGURA 12
25
15
00f( •
·K
0K
0G
.
K
. °K
0G ·K
0 K
00K ·K
0K0G
0K
0K
·K '
0 K'
5 ----------------H_w------------------
1 0 20
·K
·:;:· .. ,.i.'·:· ·.
- .. ..;..
FIGURE 12

140 F. ETA YO · SERNA
Scatter diagram of the relationships between
Euw and . H, and the accompanying variation
in type and numher of ribs in Eadouvi-
FIGURE 13
lleiceras (?) tequendamai n. sp., type sample
C-223.

FIGURA 13
2
15
tn• to•
10
t n•
OD'
Hw
20
FIGURE.l3

142
Scatter diagram of the relationships be·
tween Euw and H and the accompanying va·
riation in number of ribs in Du{renoyia sancto·
F. ETA YO - SERNA
FIGURE 14
rum Biirgl (=S, Sm), and Dufrenoyia hansbuer·
gli n. sp., (=Th).Data from Blirgl 1956b, Table I.

FIGURA 14 FIGURE 14
jl: ·s
::J
....
·sm
· s
. s
·Sm
'Sm
'Sm ·S ·Sm
·s ·s
' Sm
·Th
0S·Sm ·Sm
·s · s ·sm
·s
·Sm • ·Th ·Th ·Th
0s ·S ·Tb• Th
·sm
·Th
Hw
•Tb
·Tb
20 30 40
· . I

144 F, ETAYO ·SERNA
Scatter diagram of the relationships between
Euw and H and the accompanying variation
in type and number of ribs in Neodes-
FIGURE 15
hayesites columbianus (Riedel), reference sample
C-12-C.

FIGURA 15
3
1
A• •F
•A
•F
•n •F •F
•F' •F
•F •A
FeF
.n • •E
•F' •F •F
•F •F
• •F
•A
•F
A • • •F'
•F
E••F •A
•D •A
Hw
FIGURE 15
-- -- -,- -- -- -- -- -- -- -- -- -- --r- -- -- -- -- -- -- -- -- --
5--- 10 20 30

146
F. ETA YO · SERNA
FIGURE 16
Scatter. diagram of the relationships between
Euw and H and the accompanying variation
in type and number of ribs in Neodes·
hayesites albertoaluarezi n. sp., type sample
G-219.

FIGURA 16 FIGURE 16
2
1
1
Hw
10 20 30

148 F. ETA YO · SERNA
Scatter diagram of the relationships be·
tween Euw and H and the accompanying va·
riation in type and number of ribs in Neodesha·
FIGURE 17
yesites karsteni (Marcou), Reference sample
C-501.

FIGURA 17
35
25
15
eB
• c eA
Ee ec
A(B•) 8 A
•n •n
HW
5--- -- -- -- -- -- -- --.r- -- -- -- -- -- -- -- -- -- -.- -- -- -- -- -
ec
8B
e s en
10 20 30
ec
FIGURE 17

PLATES 1-15

152
F. ETA YO · SERN A
PLATE 1
Fig. 1) Du{rcnoyia codazziana (Karsten), La Fig. 5) Gargasiceras interiectum (Riedel), La
Ye, ( x 1 1/10).
Ye-5 bis (x 1).
Fig. 2) Du{renoyia sanclorum (Burgi), hypo· Fig. 6) Du(renoyia boleroi n. sp., holotype
type La Ye-7 (x 1 2/100).
C-223-x-10, (x 1).
Fig. 3) Du{renoyia sanctorum (Burgi), morph
1, La Ye (x 1 3/100).
Fig. 4) Du{renoyia hansbuergli n. sp., hypoty·
pe C-223-x-28 (x 1).
Fig. 7) Du{renoyia codazziana (Karsten), La
Ye-2 (x 1).
Fig. 8) Du{renoyia codazziana Karsten J ,
morph II, La Cumbre x 1 1/1 ).
Plate 1. Ammoni from the Du(re noyia sanclorum·Stoyanowlceras tre{{ryanus Assembla-
. ·.
ge zone. F1gs. 1·8. Upper Aptian.
......

154 F. ETA YO · SERNA
Fig. 1) Cheloniceras (Epicheloniceras) barreroi
n. sp., holotype C-514 (x 1 7/10).
Fig. 2) Cheloniceras (Epicheloniceras) pardoi
n. sp., holotype C-504 (x 1 12/100).
Fig. 3) Cheloniceras (Epicheloniceras cama·
choi n. sp., holotype VL-10-17 (x 1).
Fig. 4) Ch eloniceras (Epicheloniceras) huertasi
n. sp., holotype VL-7-Sa-11 (x 1).
Fig. 5) Cheloniceras (Epicheloniceras) dognaelvirae
n. sp., holotype VL-12-2 (x 1
5/100).
PLATE 2
Fig. 6) Eodouvilleiceras (?) lequendamai n. sp.,
holotype C-223-21, (x 1 12/100).
Fig. 7) Cheloniceras (Epicheloniceras) (?)
amazonarum (Burckhardt) , hypotype
C-5 14 (x 1).
Fig. 8) Cheloniceras (Epicheloniceras) jimenoi
n. sp., holotype C-514 (x 1).
Fig. 9) Cheloniceras (Epicheloniceras) carlosacostai
n.sp., holotype C-223-16 (x 1).
Fig. 10) Cheloniceras (Epicheloniceras) carlosacoslai
n. sp., holotype C-223-16 (x 1
16/100).
Plate 2. Ammonites from the Du{renoyia sanctoru m-Stoyanowiceras tre{(ryanus Assemblage
zone. Figs. 1-10. Upper Aptian.
-·

156 F. ETA YO ·SERNA
Fig. 1) Pseudosaynella ralphimlayi n. sp., holotype
SV-28 (x 1 2/10).
Fig. 2) Corteziceras cortezi n. sp., holotype
Santa Ana (x 1).
Fig. 3) Acanthohoplites (?) serpentiforme n.
sp., holotype C-157 (x 1 77/100).
Fig. 4) Pseudohaploceras leivaense n. sp., holotype
VL-10-17 (x 1).
Fig. 5) Juandurhamiceras juandurhami n. sp.,
paratype Santa Ana 31 (x 1 4/100).
Fig. 6) Corteziceras (!) n.sp., ind., C-5 13 (x 1).
Fig. 7) Corteziceras cortezi n. sp., morph I,
Santa Ana (x 1).
PLATE 3
.
Fig. 8) Stoyanowiceras treffryanus Karsten,
morph I (x 1 3{100).
Fig. 9) Melchiorites media Riedel, hypotype C·
157 (x 1 72/100).
Fig. 10) Valdedorsella (?) colombiana n. sp.,
holotype Santa Ana (x 89/100).
Fig. 11) Hypacanthoplites (?) dognaliciae n. sp.,
holotype T.P.I. Guaduas (x 1 2/100).
Fig. 12) Stoyanowiceras treffryanus Karsten,
morph II, Penn. 7 (x 1 8/100).
Fig. 13) Juandurhamiceras giraldoi n. sp., bolotype
Santa Ana 42 (x 1 8/100).
Plate 3. Ammonites from the Dufrenoyia sanctorum-Stoyanowiceras tre((ryanus Assembla·
ge zone .. Figs. 1-2, 4-8, 10·13. Ammonites from the Parahoplites (?) hubachi-Acanthohoplrtes
(?) leptocerati(orme Assemblage zone. Figs. 3, 9. Upper Aptian.
.... ...

158 F. ETA YO · SERN A
PLATE 4
Fig. l) Stoyanowiceros tre{fryanus Karsten, Fig. 5) Juandurhamiceras joepecki n. sp., San-
Pensilvania (x 1 2/10),hypotype. ta Ana 9 (x 1 2/100).
Fig. 2) Juandurhamiceras juandurhami n. sp., Fig. 6) Corteziceras latecostata (Riedel), C-255
holotype Santa Ana 30 (x 1). (x 1).
Fig. 3) Riedelites obliquum (Riedel), bypotype
C-200 D (x 1 2/10).
Fig. 4) Acanthohoplites odiosus n. sp., bolo·
type C-127(x1.4{100).
Fig. 7) Stoyanowiceras lreffryanus (Karsten)?
Penn. 13 (x 1 25/100).
Fig. 8) Heminautilus etheringtoni Durham,
hypotype (x 1 2/10).
Plate 4. Ammonites from the Du{renoyia sanctorum-Stoyanowiceras treffryanus Assemblll
ge zone. Figs. 1-3, 5, 7-8. Ammonites from the Prahoplites ('?) hubachi-Acantho
hoplites ('?) leptocerati{onne Assemblage zone. Figs. 4, 6. Upper Aptian.
v

160 F. ETAYO · SERNA
PLATE S
Fig. 1) Parahoplites (?) hubachi n.sp.,holotype Fig. 6) Parahoplites(!) hubachi n.sp., morph I,
C-127 (x 1 2/10). C-127 (x 1).
Fig. 2) Acanthohoplites bigoureti{orme n. sp., Fig. 7) Gargasiceras (?) juanwyatti n.sp., boloholotype
C-127 (x 1 4/100). type C·151 (x 1).
Fig. 3) Stoyanowiceras treffryanus (Karsten),
Penn. (x 1), hypotype.
Fig. 4) Acanthohoplites eleganteante n. sp., Fig. 9)
holotype C-127 ( x 1 4/100).
Fig. 5) Acanthohoplites triston n. sp., bolotype
C-127 (x 1).
Fig. 8) Acanthohoplites luisperezi n. sp., bolotype
C-157 (x 82/100).
Heminautilus e theringtony Durham,
hypotype (x 1 3/10).
Plate 5. Ammonites from the Dufrenoyia sanctorum-Stoyanoeras treffryanus Assembla·
ge zone. Figs. 3, 9. Ammonites from the Parahoplites (?) hubachi-Acanthohoplites
(?) lep tocerati(orme Assemblage zone. Figs. 1·2, 4-8 Upper Aptian.
v

162
Fig. 1) Vectisites (Zambranoites) zambranoi
n. sp., holotype C-504 (x 1).
Fig. 2) Ve ctisites (Zambranoites) duquesi n.
sp., holotype C-514 (x 1).
Fig. 3) Cheloniceras (Epichetoniceras) leonhardtriedeli
n. sp.,hypotype (x 1).
Fig. 4) Ve ctisites (Zambranoites) cadenai n.
sp., holotype C-514 (x 1).
Fig. ·5) Colombiceras (?) sarmientoi n. sp.,
holotype C-5 13 (x 1).
Fig. 6) Melchiorites palmeri n. sp., holotype
C-223 (x 1).
Fig. 7) Riedelites obliquum (Riedel), morph I,
C-5 14 A (x 1). Hypotype.
Fig. 8) Gargasiceras in teriectum ( Riedel),
morph I, La Ye 4 his (x 1 2/10).
Fig. 9) Vectisites (Zambranoites) cruzi n. sp.,
holotype (x 1).
Fig.10) Melchiorites palmeri n. sp., paratype
C-200 (x 1).
F. ETA YO · SERNA
PLATE 6
Fig.ll) Eogaudryceras (Eotetragonites) cabaricoi
n. sp., holotype C-513 (x 87/10).
Fig.12) Riedelites esthersernae n. sp., holotype
C-222A (x 1).
Fig.13) Colomblceras {oreroi n. sp., holotype
C-200-7 (x 1 1/10).
Fig.14) Eogaudryceras (Eogaudrycerus) helmsi
n. sp., holotype C-223 (x 1).
Fig.15) Aconeceras gutierrezpalmae n. sp., ho­
Jotype C-223 Jx 1 6/10).
Fig.16) Riede lites (?) quebradanegra nsp., hypo·
type C-200 A (x 1 26/100).
Fig.17) Pseudoptychoceras gilberti n. sp.,
morph I C-223 (x 1 42/100).
Fig.18) Pseudoptychoceras gilberti n. sp., ho·
Jotype C-223 (x 1 44/100).
Fig.19) Toxoceratoides (Colomboceraloides)
renzoni n. sp., holotype LB·10 (x 1).
Fig.20) Vectisites (Zambranoites) mateusi n.
sp., holotype VI-11-3 (x 1 33/100).
Plate 6. Ammonites from the Du{renoyia sanciorum-Stoyano;Jceras tre{fryanus Assembla·
ge zone. Figs. 1·20. Upper Aptian.

164
Fig. 1) Riedelites filosum n. sp., holotype .
C-255-6 (x 1).
Fig. 2) Acanthohop/ites quitasuegno n. sp.,
holotype C-127 (x 1).
Fig. 3) Acanthohoplites pluricostatum n. sp.,
holotype C-127 (x 1).
Fig. 4) Acanthohoplites leptocerati{orme
n. sp., holotype C-127 (x 1).
Fig. 5) Douvilleiceras tarapacaense n. sp.,
paratype C-218 (x 1).
F. ETA YO · SERNA
PLATE 7
Fig. 6) Douvilleiceras solitae (D'Orbigny),hy·
potype C-160A (x 1).
Fig. 7) Douvilleiceras solitae (D'Orbigny),hy·
potype C-160A (x 1).
Fig. 8) Acanthohop/ites seunesi{orme n. sp.,
holotype C-127 (x 1 1/10).
Fig. 9) Stoyanowiceras cintatum n. sp., bolo·
type T. P. Guaduas (x 1 1/10).
Plate 7. Ammonites from the Du{renoyia sanctorum-Stoyanowiceras tre{{ryanus Assembla·
ge zone. Fig. 9. Ammonites from the Parahoplites (?) hubachi-Acanthohoplites (?)
leptocera ti{orme Assemblage zone. Figs. 1·4, 8. Upper Aptian. Ammonites from
the Douvilleiceras solitae-Neodeshayesites columbianus Assemblage zone. Figs. 5-7.
Lower Albian.
v

166 F. ETA YO · SERNA
Fig. 1) Eodouuilleiceras pedrocaruaja/i n.sp.,
holotype C-170 (x 1).
Fig. 2) Douuilleiccras larapacaense n. sp.,
holotype c. 218-10 (x 1).
Fig. 3) Neodeshayesites albertoaluarezi n.sp.,
holotype C-129-1 (x 1).
Fig. 4) Phylloceras buchianum (Forbe ,hypotype
C-217 (x 2).
Plate 8.
PLATE 8
Fig. 5)
Fig. 6)
Fig. 7)
Holcophylloceras hernandezi n. sp.,
holotype C-13 (x 1 8/10).
Douvilleiceras tarapacaense n. sp.,
holotype C-218-10 (x 1).
Douuil/eiceras abozagloi n. sp., holotype
C·215 (X 1 6/100).
Ammonites from the Douuilleiceras solitae-Neodeshayesites columbianus Assem
blage zone. Figs. 1-7. Lower Albian.
......
)

168 F. ETA YO · SERNA
Fig. 1) Trochleiceras juliverti n. sp., holotype
•
C-215·1 (x 2 64/100).
Fig. 2) Ne odeshayesites karste11i (Marcou),hY·
pctype C-501·1 (x 1 8/100).
Fig. 3) Neodeshayesites albertoalvarezi n. sp.,
paratype C-219 (x 1).
Fig. 4) Rinconiceras rinconi s. sp., holotype
C-169-3 (x 1).
PLATE 9
Fig. 5) Lyelliceras pseudolyelli{orme n. sp.,
holotype C-255 (x 1).
Fig. 6) Ralphimlayites apuloense n. sp., bolo·
type C·510A (x 1 29/100).
Fig. 7) Neodeshayesites contracta (Riedel),hy·
potype C-500·6 (x 1 9/100).
Fig. 8) Neodeshayesites columbianus (Riedel),
hypotype C-12-C·S (x 1 4/100).
Plate 9. Ammonites fr m the Douvilleiceras solitae-Neodeshayesites columbianus Assem·
blage z!lne. tgs. -3, 7-8: Lower Albian. Ammonites from the Platiknemiceras
c?lombwna : Rmcomcras nnconi-Lyelliceras pseudolyelliforme Assemblage zone.
F1gs. 4-6. Mtddle Albtan.
)

170
Fig. 1) Carloscaceresiceras caceresi n.sp., halo·
type C-170·20 (x 1 8/100).
Fig. 2) Parahoplites (?) inconstans Riedel ?,
C-501-13 (x 1).
Fig. 3) Hypophylloceras wiedmanni n. sp., ho·
lotype C-2fi!'i (x 1).
F. ETA YO - SERNA
PLATE 10
Fig. 4) Trochleiceras (Jaumaportaiceras) hoffs·
tetteri n. sp., holotype C-215 (x2 2/10).
Fig. 5) Carloscaceresiceras mon teroi n. sp.,
holotype C-13-33 (x 2/10).
Fig. 6) Neodeshayesites karsteni (Marcou)
n. sp., morph I, C-501-14 (x 1).
Fig. 7) Ne odeshayesites columbianus (Riedel),
paratype C-12C-25 (x 1 12/100).
Fig. 8) Neodeshayesites cingula tum n. sp., paratype
C-501-21 (x 1).
Fig. 9) Neodeshayesites karsteni (Marcou) ,
morph I C-501 (x 1).
Fig. 10) Neodeshayesites cingulatum n. sp., ho·
lotype C-501·0 (x 1 8/100).
)
Plate 10. Ammonites from the Parahoplites ('?) hubachi·Acantliohoplites ('?) leptocerati{orme
Assemblage zone. Figs. 2·3. Upper Aptian. Ammonites from the Douvilleiceras
solitae-Neorl.eshayesites columbianus Assemblage zone. Figs. 1, 3-10. Lower AJbian.

174
Fig. 1) Engonoceras (?) duartei n. sp., holotype
VL Est. 33a (x 9/10).
Fig. 2) Knemiceras pegnai n. sp., holotype C-
131 (x 6/10).
F. ETA YO · SERNA
PLATE 12
Fig. 3) Platiknemiceras sp. ind. B., VL. Est.
33a (x 1).
Fig. 4) Enl(onoceras (?) duartei n. sp ., holotype
VL- Est. 33a (x 81/100).
Plate 12. Ammonites from the Platiknemiceras colombiana-Rinconiceras rinconi-Lyelliceras
pseudolyelliforme Assemblage zone. Figs. 1-4. Middle Albian.

176
Fig. 1)
Fig. 2)
Fig. 3)
Fig. 4)
Fig. 5)
Fig. 6)
Fig. 7)
Fig. 8)
Fig. 9)
Ma mmites nodosoidesappelatus n. sp.
holotype C.310 (x 1).
Franciscoites suarezi n. sp., holotype
C-310 (x 1 37/100).
Imlayiceras (?) ralphimlayi n. sp., ho·
lotype C-310 (x-1).
Hoplitoides hernanmojicae n. sp., ho·
lotype C.310 (x 1).
Paramammites colombianus n. sp., bolotype
LVZ-7 (x 1).
Ma mmites fugax n. sp., holotype c-
263 (x 1).
Lewesiceras (?) ulloai n. sp., holotype
C-310 (x 1).
Hoplitoides hernanmojicae n. sp., paratype
C-310 (x 1).
Hoplitoides lacabagnae n. sp., holoty·
pe (x 1).
F. ETA YO · SERNA
PLATE 13
Fig. 10) Mammites scutulatus n. sp., holotype
C·310 (x 1).
Fig. 11) Fagesia zanellai n. sp., holotype C-310
(x 1).
Fig. 12) Prionocycloceras portarum n. sp., ho·
lotypE' C-134 ( x 1).
Fig. 13) Paramammites colombianus n. sp.,
bolotype LVZ-7 (x 1).
Fig. 14) Hoplitoides lagiraldae n. sp., holotype
C-264 (x 1).
Fig. 15) Hoplitoides (?) sp. ind., C·310 (x 1).
Fig.16) Prionocyclaceras longispinatum(Basse ) ,
hypotype C-134 (x 1).
Fig. 17) Codazziceras {ina n. sp., holotype
C-134 (X 1 15/100).
Fig. 18) Gloriaceras correai n. sp., holotype
NRC-Ca-1-5 (x 1 26/100).
Fig. 19) Gloriaceras paulinae n. sp., holotype
NRC·CU-5 (x 1).
Plate 13. Ammonites from the Mammites nodosoidesappelatus-Franciscoites suarezi Assem­
blage zone. Figs. 1-11, 13-15. Lower 'furonian. Ammonites from the Gloriaceras
correai-Protexanites cucaitaense-Codazziceras scheibei Assemblage zone. Figs. 12,
16-19. Lower Coniacian.

178 F. ETA YO · SERNA
PLATE 14
Fig. 1) · Peroniceras diabloi n. sp., holotype Fig; 6)
NRC-=( x 1).
Fig. 2) Buenoceras loboi n. sp., holotype Fig. 7)
NRC-4 (x 1).
Fig. 3) Peroniceras guerrai n. sp., holotype Fig. 8)
NRC-Est. 9 (x 1).
Fig. 4) Prionocycloceras portarum n. sp., ho· Fig. 9)
lotype C-134 ( x 1).
Fig. 5) Fagesia zanellai n. sp., holotype C-310
(x 1).
Fig.10)
Zumpangoceras (?) sorae n. sp., holotype
NRD-Sora (x 1).
Nice{oroceras boyacaense n. sp., bolo·
type NRC-9 (x 1).
Zumpangoceras ospinai n. sp., holotype
NRC-1 ( x 1).
Prionocycloceras (?) cucaitaense n. sp.,
holotype NRC-5, (x 1 12/100).
Gloriaceras correai n. sp., holotype
·
NRC-Ca -l 5 (x 1).
Plate 14. Ammonites from the Mammites nodosoidesappelatus-Franciscoites suarezi Assem­
blage _ zone. Fi. 5. Lower ronian. Ammonites fro"fu the Gloriaceras correai-Pro­
texamte c uca1taense-Codazzzceras scheibei Assemblage zone. Figs. 1-4 7-10. Lo-
.
wer Comactan.
r
'

180
Fig.1)
Codaziceras scheibei (Riedel), hypo
type C-134 (x 1 6/100).
Fig. 2) Peroniceras robertogarcille n. sp., ho·
loty VL6, CU-5 (x 1 13/100).
F. ETA YO · SERNA
PLATE 15
Fig. 3) Protexanites cucaitaense n. sp., holoty·
pP VL6·CU·3 (x 1 12/100).
Fig. 4) Pro texanites cucaitaense n. sp., holoty·
pe VL6-CU·3 (x 1 16/100).
Plate 15. Ammonites from ·the Gloriaceras correai-Pro texanite&· cucaitaense-Codazziceras
scheibei Assemblage zone. Figs. 1·4. Lower Coniacian.

Acanthoceras, 84.
?ospinae (Karsten), 84.
Acanthohoplites, 44. ._
abichi Anthula, 51. .aschiltaensis
(Anthula), 44.
bigoti (Seunes), 4 7.
bigoure ti (Seunes), 4
bigouretiforme, n.sp., 44, (Plate 5,p.160),
(Text. fig. 5, p.124).
'derognati Roch', 46. .
eleganteante, n. sp ., 47, (Plate 5, p.160),
(Text. fig. 5, p. 124).
·
leptocerati(o rme, n.sp., 47 ,(Plate 7, p.164)
·
(Text. fig. 5, p. 124).
luisperezi, n. sp., 4 7,- (Plate 5, p. 160),
(Text. fig. 5, p. 124).
odiosus, n. sp., 46, (Plate 4, p.158),(Text.
fig. 5, p. 124).
pluricostatum, n. sp., 46, (Plate 7, p.164),
(Text. fig. 5, p.124).
quitasuegno, n. sp., 45, (Plate 7. p. 164),
(Text. fig. 5, p.124).
rochi Breistroffer, 45.
serpentiforme, n. sp., 49, (Plate 3, p.
156), (Text. fig. 5, p. 124). ·
seunesi (Jacob), 45.
seunesi(orme, n. sp., 45, (Plate 7, .164),
(Text. fig. 5, p.l24).
Aconeceras, 22.
gutierrezpalmae, n.sp., 22, (Plate 6, p.162),
(Text. fig.3, p.120).
nisoides (Sarasin), 23.
nisus (d'Orbigny), 23.
Barroisiceras, 97, 99.
alstadenense Solger, 101.
subtuberculatum (Gerhardt), 102.
Benueites, 86.
spinosus Reyment, 86.
Brancoceras, 79.
? carinatum Collignon, 79.
Buenoceras, n. g., 101.
loboi, n. sp., 101, (Plate 14, p.178),
(Text. fig. 9, p. 132).
Burckhardites, 67.
pa/umbes Humphrey, 67.
Carloscaceresiceras, n.g., 25. ·
caceresi, n. sp., 25, 26, (Plate 10, p.170),
(Text. figs. 4, p. 122; 10, p. 134).
? chimuense (Benavides-Caceres), 27, (Plate
11, p. 172), (Text. fig. 4, p. 122).
monteroi, n. sp ., 26, (Plate 10, p. 170),
(Tex t. fig. 4, p. 122; 10, p.134).
Codazziceras, n.g., 83.
(ina, n. sp., 84, (Plate 13, p. 176), (Text.
fig. 8, p. 130).
scheibei (Riedel), 83, (Plate 15, p. 180),
(Text. fig. 8, p. 130).
stutzeri (Riedel), 85.
Colombiceras, 49, 69, 70.
caucasicum Luppov, 49, 70.
crassicostatus (d'Orbigny), 49.
(oreroi, n. sp., 50, (Plate 6, p.162), (Text.
fig. 6, p.126).
sarmientoi, n. sp., 50, (Plate 6, p. 162),
(Text. fig. 6, p. 126).
tobleri (Jacob), 50, 51.
Colombocera toides, ri. sg., 20.
renzom, . n. sp., 20 (Plate 6, p.162), (Text.
INDEX OF GENERA AND SPECIES
fig. 3, p.120).
(orph 1), 21 (Text. fig. 3, p.120).
183
Cortezzceras, n. g., 27.
cortezi, n. sp., 27, (Plate 3, p.156), (Text.
fig. 4, p. 122).
· (morph 1), 28, (Plate 3, p. 156).
la tecostata (Riedel), 28; (Plate 4, p. 158),
Text. fig. 4, p. 122).
. n. sp., 29, {Plate 3, p.156), (Text. fig. 3,
p.120).
;
Cheloniceras, 32.
basseae Breistroffer, 38.
clansayesense (Jacob), 36.
aff. comuelianum (d Orbigny), 32.
. stoliczkanum (Gabb), 33.
Desmoceras, 24.
'akuschaense Anthula' 24.
'hyattum (Gabb)', 25.
'sparsicosta Boese', 25.
Discoceras, 91.
cf. largilliertianus (d'Orbigny), 91.
Donjuaniceras, 94.
Douuilleiceras, 53.
abozagloi, n. sp., 55, (Plate 8, p. 166).
albense Spath, 56.
mammilla tum (Schlotheim), 54, 57.
·
·
'martini d'Orb. , 35 .
monile (J. Sowerby), 54, 56.
multinodosum Rhein, 54.
solitae (d'Orbigny), 54, (Plate 7, p.164),
(Text. fig. 6, p.126). . ·
tarapacaense, n. sp., 54 (Plate 7, p.164;
Plate 8, p. 166), (Text. fig. 6, p. 126).
Dufrenoyia, 58.
boteroi, n.sp., 58, (Plate 1, p.152), (Text.
fig. 5, p. 124).
.
codazziana (Karsten), 58, (Plate 1, p.152).
discoidalis Casey , 60.
durangensis Humphrey, 60.
formosa insculpta Casey , 59.
furcata (J. de C. Sowerby), 58.
hansbuergli, n.sp., 60, 61, (Plate 1, p.152),
(Text. fig. 14, p. 142).
justinae (Hill), 59.
media Buergl, 60.
mulatoensis Humphrey, 59.
notha Casey, 60.
sanctorum Buergl, 59, (Plate 1, p. 152),
(Text. fig. 14, p. 142).
(morph 1), 60, (Plate I, p.152), (Text. fig.
14, p. 142).
scalata Casey, 58.
texana Burckhardt, 61.
Eodouuilleiceras, 56.
horridu m (Riedel), 57.
pedrocarvaja/i, n. sp., 57, (Plate 8, p.166),
(Text. fig. 6, p.126).
tequendamai, n. sp., 57, (Plate 2, .p. 154),
(Text. fig. 6, p. 126; 13, p. 140).
Eogaudryceras, 19.
helmsi, n. sp., 19, (Plate 6, p. 162), (Text.
fig. 3, p. 120).
numidum var. in termedia (Fallot), 20.
vocontian um (Fallot), 20.
Eote tragonites, 20.
cabaricoi, n. sp., 20, (Plate 6, p. 162),
(Text. fig. 3, p. 120).
jacobi ambigua Breistroffer, 20.

184
Engonoceras, 74.
duartci, n. sp., 75, (Plate 12, p. 174).
gibbosum Hyatt, 75.
o/galuciae, n. sp., 74, (Plate 11, p. 172),
(Text. fig. 8, p. 130).
pierdenalis (von Buch), 7 4.
stolleyi Bohm, 75.
sp., 75, (Plate 11, p. 172).
uddeni (Cragin), 75.
Epicheloniceras, 32.
amazonarum (Burckhardt), 33, (Plate 2,
p. 154), (Text. fig. 4, p. 122).
barreroi, n. sp., 36, 58, (Pl ate 2, p. 154),
(Text. fig. 4, p. 122).
carlosacostai, n. sp., 34, (Plate 2, p. 154),
(Text. fig. 4, p. 122; 11, p. 136),
camachoi, n. sp., 33, (Plate 2, p. 154),
(Text. fig. 4, p. 122).
de bile Casey , 33.
dognaelvirae, n. sp., 32, (Plate 2, p. 154),
(Text. fig. 4, p. 122).
huertasi n. sp ., 37, (Plate 2, p. 154),
.(Text. fig. 4 , p. 122).
jimenoi, n. sp., 35, (Plate 2, p. 154),
(Text. fig. 4, p. 122).
leonhardtriedeli, n. sp., 37, 58, (Pl. 6, p.
162), (Text. fig. 4, p. 122).
pardoi, n. sp., 37, (Plate 2, p. 154), (Text.
fig. 4, p. 122).
subnodosoc()slatum (Sinzow), 35.
Eubrancoceras, 79.
aegoceratoides (Steinmann), 79.
Fagesia, 89.
peroni colombiana Fritsche, 90.
superstes (Kossmat), 89.
lhevestensis (Peron), 90.
zanellai, n. sp., 89, (Plate 13, p. 176; 14,
p. 178), (Text. fig. 8, p. 130).
Forresteria, 99. _
. ,, cf. allaudi (Boule, Leomoine, Thevenine),
.. .. . 99 .
.-· (o rresten· Reeside, 100.
Frariciscoites, n. g., 87.
· suarezi, n. sp., 87, (Plate 13, p. 176),
· (Text. fig. 8, p.130).
toroanus (Karsten), 87.
Gargasiceras, 51.
gargasensis (d'Orbigny), 51.
interiectum (Riedel), 51, (Plate 1, p.152),
· (Text. fig. 6, p. 126).
. · (morph 1), 52, (Plate 6, p. 162), (Text.
fig. 6. p.126).
juanwyalti, n. sp., 53, (Plate 5, p. 160),
(Text. fig. 5, p. 124).
· pulcher (Riedel), 53.
Glonaceras, n. g., 96.
. ,.,_. . correai, n. sp., 96, 97, (Plate 13t p. 176;
- ··. Pia 14, p. 178), (Text .. fig. 9,:'P· 132).
··
paulmae, n. sp., 98, (Plate 13, p. 176),
(Text. fig. 9, p. 132).
Heminautilus, 104.
etheringtoni Durham, 104, (Plate 4, p.
158; Plate 5, p. 160).
saxbii (Morris), 104.
Hoplitoides, 89, 90.
inca Benavides-Caceres, 89.
ingens (von Koene), 91.
ingens laeuis (Solger), 91.
hernanmojicae, n.sp., 90, (Plate 13, p.176).
" lacabagnae, n.sp., 91, (Plate 13, p. 176).
lagiraldae, n. sp., 92, (Plate 13, p. 176).
l.ltesellatus von Koenen, 89, 92.
munieri Pervinquhhe, 89.
sp. ind., 92, (Plate 13, p. 176).
Holcophylloccras, 17.
guet tardi (Raspail ), 18.
hernandezi, n.sp., 17, 18, (Plate 8, p.166),
(Text. fig. 3, p. 120).
Hypacanlhoplites, 41.
dognaliciae, n. sp., 41, (Plate 3, p. 156).
plesiotypicus (Frittel ), 41.
Hypophylloceras, 18.
subserecitense Wiedmann, 19.
wiedmanni, n. sp., 18, (Plate 10, p. 170),
(Text. fig. 3, p. 120).
Hysteroceras, 79.
d'orbigny Spath, 79.
Imlayiceras, 88.
ralphimlayi, n. sp., 88, (Plate 13, p. 176),
(Text. fig. 8, p. 130).
washbournei, 88.
Jaumaportaiceras, n. sg., 31.
ho{{stetteri, n. sp., 31, (Plate 10, p. 170),
(Text. fig. 4, p. 122).
Juandurhamiceras, n. g. 42.
giraldoi, n. sp ., 43 (Plate 3, p. 156).
joepechi, n. sp ., 43, (Plate 4, p. 158).
juandurhami, n.sp., 42, (Plate 3, p.156;
Plate 4, p. 158), (Text. fig. 5, p. 124;
Text. fig. 12, p. 138).
Knemiceras, 77.
pegnai, n. sp., 77, (Plate 12, 174), (Text.
fig. 8, p. 138). .
raimondi Lisson, 78. .
raimondi tardum Benavides-Caceres, ·78.
semicostalum Sommermeier, 77, (Plate
11, p. 172), (Text. fig. 8, p. 130).
syriacus (von Buch ), 77.
Lewesiceras, 30 .
ubalense Leanza, 88.
ulloai, n. sp ., 30 (Plate 13, p. 176), (Tex t .
.
fi 4, p. 122
Lyelliceras, 79.
carvajalorum, n.sp., 79, (Plate 11, p.172),
(Text. fig. 8, p. 130).
isaacleai, n. sp., 80, (Plate 11, p. 172).
lyelli (Deshayes), 79.
pseudo!yelli (Parona & Bomarelli), 80.
pseudolyelli{orme, n.sp., 80, (Plate 9, p.
168l,. (Text. fig. 8, p. 130).
Ma croscaphiles, 49 .
Magneticeras, 31.
magne ti Collignon, 31.
Mammites, 85.
{ugax, n.sp., 86, (Plate 13; p. 176), (Text.
fig. 8, p. 130).
nodosoides (Schlotheim), 85. .
nodosoides a{ra Pervinquhre, 86.• .· · ·
nodosoidesappelatus, n.sp., 85, (Plate 13,
p. 140). .
revelierianum Coustillier, 87.
scutulatus, n. sp . .t 87, (Plate 13, p. 176);
(Text. fig. 8, p. 1010).
Melchiorites, 23.
media Riedel, 23, 24, {Plate 3, p. 156),
(Text. fig. 3, p. 120).
melchioris (Tietze), 23.
palmeri, 23, (Plate 6, p. 162), (Text. fig.
3, p. 120). -.,.
Ne odeshayesites, 62, 64.

albertoalvarezi, n. sp., 63, 64, (Plate 8,
p. 166; Plate 9, p. 168), (Text. fig. 6,
p. 126; Text. fig. 16 p. 146).
cingulatum, n. sp., 66, (Plate 10, p.170),
(Text. fig. 7, p. 128).
colu mb ianus (Riedel), 62, (Plate 9, p.168;
Plate 10, p. 170);''"(Text. fig; 6, p. 126;
Text. fig. 15, p. 144).
con tracta (Riedel), 66, (Plate 9, p. 168),
(Text. fig. 7, p. 128).
karsleni (Marcou), 64, (Plate 9, p. 168;
Plate 10, p. 170), (Text.: fig. 6, p. 126;
Text. fig. 17, p. 148).
(morph 1), 66, (Plate 10, p. 170) (Text.
fig. 17, p. 148).
Neoptychites, 87.
Nice{oroceras, 92.
boyacaense, n. sp., 92, (Plate 14, p. 178).
columbianus Basse, 92.
umbulazi{orme Basse, 92.
Parahoplites, 72, (Plate 5, p. 160).
hubachi, n. sp., 72 (Plate 5, p. 160).
(morph 1), 73, (Plate 5, p. 160), (Text.
fig. 5, p. l24).
incons lans Riedel, 74, (Plate 10, p. 170),
(Text. fig. 5, p. 124).
melchioris Anthula, 72.
mullicostatus Sinzow, 73.
nicholsoni Benavides-Caceres, 70.
numidicus Somay, 74.
tristan, n. sp., 73, (Plate 5, p. 160),
(Text. fig. 5, p. 124).
Paramammites, 90.
colo mbianus, n. sp., 90, (Plate 13, p. 176).
gracilis (Pervinquiere), 90.
po/ymorphus (Pervinquilre), 90.
Parengonoceras, 75.
ebrayi (de Lorio!), 78.
elegans Renz, 75.
Paroxy tropidoceras, 79.
Pedioceras, 53.
Peroniceras, 92.
czornigi de Grossouvre, 97.
diabloi, n. sp., 93, (Plate - 14, p. 178),
(Text. fig. 9, p. 132).
dravidica Kossmat, 97.
guerrai, n.sp., 94, (Plate 14, p.178). (Text.
fig. 9, p. 132).
leei Reeside, 97.
moureti de Grossouvre, 93.
robertogarciae, n. sp., 93, (Plate 15,
p. 180), (Text. fig. 9, p. 132).
aff. rousseauxi de Grossouvre, 93.
subtricarinatum, Sturm,98, 99.
westfallicum de Grossouvre, 94.
Pegnaceras, 53.
rursiradiatus (Humphrey), 53.
Phylluceras, 17.
buchianum Forbes ?, 17, (Plate 8, p.166),
(Text. fig. 3, p. 120).
moriezense Sayn, 17.
serecitensis (Pervinquiere), 18.
velledae (Michelin), 17.
Platiknemiceras, 76.
bassei Bataller, 76.
colombiana, n. sp., 76, (Plate 11, p. 172).
gracile (Douville), 76.
sp. ind. A, 76, (Text. fig. 8, p. 130).
sp. ind. B, 76, (Plate 12, p. 174).
Prionocycloceras, 94.
·
185
acutospinatum (Basse), 96.
cucailaense, n. sp., 96, (Plate 14, p. 178),
(Text. fig. 9, p. 132).
guyabanus (Steinmann), 94.
lenti (Gerhardt), 96.
longispinalum (Basse), 94, (Plate 13,
p. 176), (Text. fig. 9, p. 132).
mediotuberculatus (Gerhardt), 95.
portarum, n. sp., 95, (Plate 13, p. 176;
Plate 14, p. 178), (Text. fig. 9, p. 132).
Prodeshayesites, 62.
Prolyelliceras, 81.
geureyi (Jacob, 82.
lobatum Riedel, 81.
peruuianum Spath, 81.
Pro lacanthoceros, 83.
Pro tacan thoplites,51.
Pro tengonocera.. 76.
gabbi (Bohm), 76.
Protexanites,97, 102.
bourgeoisi (d'Orbigny), 102.
cagnaense (Gerhardt), 102.
cucaitaense,n. sp., 102, (Plate 15, p. 180);
(Text. fig. 9, p. 132).
Pse udohaploceras, 25.
leiuaense, n.sp., 25, (Plate 3, p. 156),
(Text. fig. 3, p.120).
Pseudoptycho.ceras, n. g., 21.
gilberti, n. sp., 21, (Plate 6, p.162), (Text.
fig. 3, p.120).
(morph I), 22, {Plate 6, p. 162).
Pseudosaynella, 29.
bicurvata (Michelin), 30.
fim briata Imlay, 30.
ralphimlayi, n.sp., 29 (Plate 3, ·p : 156), ·
(Text. fig. 4, p.122).
walcotti (Hill), 30.
Puzosia, 24.
angladei Sayn, 24.
Ralphimlayites, n.g. 81.
apuloense, n. sp., 81, 82.
prorsocuruatum (Gerhardt), 81, &2.
Reesidites, 102.
minimus (Hayasaka and Fukada), 102.
.'?. iedelites, n. g., 70.
esthersernae, n. sp., 70 (Plate 6, p. 162),
(Text. fig. 7, p. 128).
filosum, n. sp., 72, (Plate 7, p. 164),
(Text. fig. 7, p. 128).
obliquum (Riedel), 70, 71.
quebradanegra, n.sp., 70, (Plate 6, p.162);
(Text. fig. 128).
Rinconiceras, n. g, 78.
Rinconi, n. sp., 78, (Plate 9, p. 168),
(Text. fig. 8, p. 130).
Schloenbachia, 101.
flexuosa Gerhardt, 101.
Stoyanowiceras, 67.
cintatum, n. sp., 69, (Plate 7, p. 164).
colombiana (Scott), 70.
tref{ryanus (Karten), 67, (Plate 4, p.158 ;
Plate 5, p. 160), (Text-fig. 7, p. 128).
(morph I), 69, (Plate 3, p.156).
(morph II), 69, (Plate 3, p. 156).

186
Tegoceras, 82.
benavidescaceresi, n. sp., 82, (Plate 11,
p. 172), (Text. fig. 8, p. 130).
camatteanum (d'Orbigny), 82.
seunesi (Parana & Bonarelli), 83.
Texanites, 83.
aff. serratomaginatus (Redtenbacher), 83.
Thomasites, 87. ·
Toxoceratoides, 20.
royerianum (d'Orbigny), 20.
Trochleiceras, 31.
ambanjabense Collignon, 32.
balearense Fallot & Tennier, 31.
juliverti, n. sp., 31.
Uhligella, 27.
latecostata Riedel, 28.
reesidei Humphrey, 28.
zurcheri Jacob & Tobler, 27.
Valdedorsel/a, 24.
* * *
colombiana, n. sp., 24, (Plate 3, p. 156),
(Text. fig. 3, p. 120).
Vascoceras, 89.
Ve ctisites, 38.
Zambranoites, n. sg., 38.
cadenai, n.sp., 40, (Plate 6, p.162), (Text.
fig. 5, p. 124).
caprotinus Casey, 38, 40.
cruz n. sp., 39, (Plate 6, p. 162), (Text.
fig., 5, p. 124).
duquesi, n. sp., 40, (Plate 6, p.162), (Text.
fig. 5, p. 124).
mateusi, n. sp., 39, (Plate 6, p. 162).
zambranoi, n. sp., M, (Plate 6, p. 162),
(Text. fig. 5, p. 124).
Zumpangoceras, 99.
burckhardti Basse, 99.
ospinai, n. sp ., 99, 100, (Plate 14,p. 178),
(Text. fig. 9, p. 132).
sorae, n. sp., 101, (Plate 14, p. 178).