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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.
Page 1 and 2: Publicaciones Geolo_gicas Especiale
Page 3 and 4: PUBLICACIONES GEOLOGICAS ESPECIALES
Page 5 and 6: CONTENTS ABSTRACT . . . . .. . . .
Page 7 and 8: Pl ate 4. Plate 6. Plate 6. Plate 7
Page 9 and 10: 2 F. ETA YO· SERNA The materials t
Page 11 and 12: 4 F. ETA YO· SERNA PHYSICAL STRATI
Page 13 and 14: FIGLH 1\ 2 2AJ Vl:LLA DE LEIVA CD -
Page 15 and 16: 8 Gloriaceras paulinae n. sp. Zumpa
Page 17 and 18: 10 F. ETA YO -SERNA coarse grained
Page 19 and 20: 12 F. ETA YO · SERNA trated in sev
Page 21 and 22: 14 F. ETA YO · SERNA ated. In the
Page 23 and 24: 16 F. ETA YO · SERNA TABLE I ASSEM
Page 25 and 26: 18 F. ETA YO ·SERNA tion consisfli
Page 27 and 28: 20 F. ETA YO ·SERNA increasing ove
Page 29 and 30: 22 has a subelliptical to subcircul
Page 31 and 32: 24 F. ETAYO ·SERNA rounds abruptly
Page 33 and 34: 26 F. ETAYO · SERNA ffer, 1963, p.
Page 35: 28 F. ETA YO - SERNA this is partic
Page 39 and 40: 32 F. ETA YO · SERNA thirds of the
Page 41 and 42: 34 F. ETA YO · SERNA Hypotype. (U.
Page 43 and 44: 36 F. ETA YO - SERN A tuberculation
Page 45 and 46: 38 F. ETAYO - SERNA they project sl
Page 47 and 48: 40 last whorl the ribs are inconspi
Page 49 and 50: 42 Hypacanthoplites dognaliciae n.
Page 51 and 52: 44 F. ETA YO · SERNA One large spe
Page 53 and 54: 46 F. ETAYO - SERNA "Acanthoplites
Page 55 and 56: 48 F. ETA YO · ERNA These tubercle
Page 57 and 58: 50 .,CQ.IQmQ.ik.er::fJ§. W forg.ro
Page 59 and 60: 52 Among the subsequent flared ribs
Page 61 and 62: ZONATION OF THE CRETACEOUS OF CENTR
Page 65 and 66: zoNATION OF THE CRETACEOUS OF CENTR
Page 71 and 72: ? ? ZONATION OF THE CRETACEOUS OF C
Page 87 and 88:
ZONATION OF THE CRETACEOUS OF CENTR
Page 89 and 90:
ZONATION OF THE CRETACEOUS OF CENTR
Page 91 and 92:
86 F. ETA YO - SERNA rent localitie
Page 93 and 94:
88 The adapical end of this conch h
Page 95 and 96:
90 F. ETAYO · SERNA dies out near
Page 97 and 98:
92 OCCURRENCE. La Frontera Fonnatio
Page 99 and 100:
94 re is an asymmetrical sulcus bor
Page 101 and 102:
96 (1898, p. 198, figs. 23a,b,c), w
Page 103 and 104:
98 the flank and have a periventral
Page 105 and 106:
100 F. ETA YO - SERNA On the adapic
Page 107 and 108:
102 ventral third of the whorl side
Page 109 and 110:
104 but "Fundort: Von Stiibel im Be
Page 111 and 112:
106 F. ETA YO · SERNA En dos regio
Page 113 and 114:
108 In due regioni della Cordiglier
Page 115 and 116:
110 REFERENCES ANDERSON, F. M. 1938
Page 117 and 118:
112 -- 1963.- Atlas des fossiles ca
Page 119 and 120:
114 KARSTEN, H. 1858.- Vber die geo
Page 121 and 122:
116 Colon. Geol. min. Resourc., uol
Page 123 and 124:
118 F. ETA YO • SERNA WIEDMANN, J
Page 125:
120 A) B) C) D) E) F) G) H) I) L) M
Page 129:
124 F. ETA YO • SERNA A) B) C) D)
Page 133 and 134:
FIGURA 7 A Q 8 ) / ! E I c K FIGUR
Page 136 and 137:
132. A) B) C) D) E) F) G) H) I) J)
Page 138 and 139:
134 Scatter diagram of the distribu
Page 140 and 141:
136 Scatter diagram of the relation
Page 142 and 143:
Page 144 and 145:
140 F. ETA YO · SERNA Scatter diag
Page 146 and 147:
Page 148 and 149:
144 F, ETAYO ·SERNA Scatter diagra
Page 150 and 151:
146 F. ETA YO · SERNA FIGURE 16 Sc
Page 152 and 153:
148 F. ETA YO · SERNA Scatter diag
Page 154 and 155:
PLATES 1-15
Page 157:
154 F. ETA YO · SERNA Fig. 1) Chel
Page 161:
158 F. ETA YO · SERN A PLATE 4 Fig
Page 165:
162 Fig. 1) Vectisites (Zambranoite
Page 169:
166 F. ETA YO · SERNA Fig. 1) Eodo
Page 173:
170 Fig. 1) Carloscaceresiceras cac
Page 179:
176 Fig. 1) Fig. 2) Fig. 3) Fig. 4)
Page 183:
180 Fig.1) Codaziceras scheibei (Ri
Page 186 and 187:
184 Engonoceras, 74. duartci, n. sp
Page 188:
186 Tegoceras, 82. benavidescaceres
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Publicaciones Geolo_gicas Especiales Del lngeominas

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