Publicaciones Geolo_gicas Especiales Del lngeominas

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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?'>
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 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: 36 F. ETA YO - SERN A tuberculation
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 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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