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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· <strong>Del</strong> 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
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: 16 F. ETA YO · SERNA TABLE I ASSEM
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 and 36: 28 F. ETA YO - SERNA this is partic
Page 37 and 38: 30 F. ETAYO ·SERNA and bifurcate;
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 67 and 68: zoNATION OF THE CRETACEOUS OF CENTR
Page 71 and 72: ? ? ZONATION OF THE CRETACEOUS OF C
Page 75 and 76:
ZONATION OF THE CRETACEOUS OF CENTR
Page 77 and 78:
zoNATION OF THE CRETACEOUS OF CENTR
Page 79 and 80:
Page 81 and 82:
Page 83 and 84:
Page 85 and 86:
Page 87 and 88:
Page 89 and 90:
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
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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
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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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