TULANE STUDIES IN GEOLOGY AND PALEONTOLOGY Volume 29, Number 4 Februc..ry :l6, 1!-:!97 --------------------------------~--------------- ANEW SPECIES OF CALYPTRAPHORUS CMESOGASTROPODA:STROMBIDAI:, FROM THE MAASTRICHTIAN OF SOUTHERN MEXICO: SOME PALEOBIOGEOGRAPHIC AND EVOLUTIONARY IMPL ICATIO~S MARIA DEL CARMEN PERRILLIAT and FRANCISCO J VEGA IN STITUTO DE GEOLOGiA, UNIVERSIDAD NACIONAL AUTO;VOiV!A DE A!EXIC'O CIUDAD UN IVERSITARIA, COYOACAN MEXICO, D. F, MEXICO. I. ABSTRACT the abundance and diversity of fo::o.sil-, al o decreases. It is interesting to :111te tnat A new species of strombid gastropod is several meters above the main loc,.li"it.>", described from the lower Maastrichtian gastropods are the only group prt.>St.>n:., and deposits from the Mexca la F ormation, their sizes are larger compared w tn . am Guerrero State, southern Mexico. More ples of the same species at the level-, wtth than 300 s pecimens of the n ew species more abundance. were collected at one locality. The speci­ The Mexcala Formation i::o. H ry comp i mens include all stages of development, cated structurally and litho:ogically. It-, from juveniles to adults. ou t crop areas include the :tate::- of Paleobiogeogr aphic a nd evolutionary Morelos, Mexico, Guerrero. and Pt...e~h It analysis for the genus of this gastropod was defined by Fries (1960, p. 2 ), based on suggests that it had a wide distribution the type section proposed by Bohnenherh around the Tethyan Province, and that Thomas (1955), as a flysch sequtr:.Ct.> uf after the K-T event, the genus migrated about 1,220 meters of rhythmic ...ltt>rna northward, until the Eocen e, when it tion of coarse and fine clastics, with lateral became extinct. and vertical variations. The :vlexcala Formation is extremely folded and fau!ted II. INTRODUCTION at the area of study. It ranges in age frum the Turonian, exposed in the central por A diverse, poorly known, and well-pre­ tion of Guerrero State (Bohnenoerg served Maastrichtian molluscan fauna has Thomas, 1955; Bose, 1923; Davila-Alcocer, been recently r estudied fr om intensive 1974; Gonzalez-Arreola. 1977: Lopez sampling at a few loca lities from the Ramos, 1983; Perrilliat-Montoya, 1974) to Upper Cretaceous Mexcala Formation in the Maastrichtian, exposed to the north Guerrero State, southern Mexico. The first east of Guerrero State (Alencaster, 1980; report of this fauna included only illustra­ de Cserna et al., 1980; Ortega-Gutit:·rrez, tions, without description, of 15 gastropod 1980). species (Alencaster, 1980), some of which In a second paper on the Texmalac were misidentified. fauna, Vega and Feldmann (1992) reported The diversity of groups present at these a new species of retroplumid crab. In this localities includes pla nktic and benthic paper, a more extensive discussion on thP foraminiferans, corals, gastropods, nau­ paleoenvironment is given, as well as some tiloids, ammonites, bivalves, scaphopods, implications on the paleobiogeographic sig­ annelids, crustaceans, echinoids, and ver­ nificance of that genus of crab. Some paly­ tebrate remains. This material was collect­ nomorphs are also reported, and some ed at three outcrops, located 125 km south were recognized as typical of the paleo flora of Mexico City, and 70 km southeast of of South America (Enrique Martinez, pers. Iguala (Fig. 1), near a town locally known comm.). Planktic fo raminiferans from the as Texmalac. studied localities include Gansserina The lithology consist s of light-brown gansseri, Rosita fornicata, Globotruncana marls, becoming sandier and blue to gray­ uentricosa, Globotrunca na li nneia na, green toward the top of the sequence, as Rugoglobigerina rugosa, Hedbergella mon- 119 120 Tulane Studies in Geology and Paleontology Vol. 29 I, \ \ I 99°00' I \.. ....-") I ......... / I I \ (' t, /..- I I ( I "I b ( ) ( Hulxc:~•tla 6 ~ I I I ............... I Chlmotocoflan / I \ I ' ' ('- ......... I \ 1 0 Ptanoho VIejo I l I I \Teooolz!ngo ) I 'p 6 I 1 Huaxtla I ' I ' \. \ I I I -..... _,, /-- ....... ---~ ~Chauolngo I Jololpon ,..- / I , J ;- ' I Atlapd '- ........ ) \ ....... ? / ....... I I \ ....... I ....... ....... I \ ....... I ....... J \ ( \ ) \ / / -N- \ r \ I 'A \ \ \ 0 25 50km. \ 1./ ~~iiiiiiiiiiiiiiiiiiiiiil ' I bcopoliflo " \ .. Papolutlo ,- - 0 ' 99°00' Figure 1. Location map of the studied area (framed) at outcrops from the Mexcala Formation near Texmalac, Guerrero. mouthensis, Globigerinelloides prairiehil­ there are some specimens which seem to lensis, H eteroh elix globulosa, and belong to new genera and new species. Pseudotextularia nuttalli. These species Among these, the new species described are indicative of a lower Maastrichtian age herein represents one of the most abun­ (Brian Huber, pers. comm.). dant gastropods, including nearly all sizes Alencaster (1980) suggested a close rela­ from juveniles to adults, the latter recog­ tionship between the Texmalac fauna and nized by the development of a callus that the faunas of the Atlantic and Gulf Coastal covers the spire completely. Plains. Preliminary systematic studies on certain gastropods and bivalves from III. SYSTEMATIC PALEONTOLOGY Texmalac (Salceda et al., 1995; Vega and Perrilliat, 1995; Vega et al., 1995) suggest Phylum MOLLUSCA Linnaeus, 1758 paleobiogeographic affinities with the Class GASTROPODA Cuvier, 1797 Atlantic and Gulf Coastal Plains, but also Subclass PROSOBRANCHIA with the Caribbean and Tethyan Pro­ Milne-Edwards, 1848 vinces. More than 25 species of gastropods Order MESOGASTROPODA Thiele, 1925 and 10 species of bivalves have been iden­ Family STROMBIDAE Rafinesque, 1815 tified, However, among the gastropods Genus CALYPTRAPHORUS Conrad, 1857 No.4 Mexican Calyptraphorus 121 Calyptraphorus CONRAD, 1857, Acad. Nat. Sci. On the presence of two nodes nn thE )a-;t v. ro ], Philadelphia, Proc., v. 9, p. 166. Type species: Rostellaria uelata Conrad, 1833, Discussion: The Mexican peri P1t'T1'> by subsequent designation, Cossmann, 1904. have no similarities to any • pecil: that Eocene; Claiborne, Alabama. have been described from the lTppt·r Cretaceous elsewhere. Ro. ·tell aria pnllzntu CALYPTRAPHORUS BINODIFERUS Forbes (1846, p. 129, pl. :1, fig. 1.'">,, fm'TI Perrilliat and Vega, n. sp. the Cretaceous of Pondicherrv, :ndict. :1as a Plate 1, figures 1-8 shell that, when full grown, becom( Plate 2, figures 1-8 enveloped by the callus, wntch ~ melop t so that only the body whorl and part of • h· Description: Shell medium-sized. Protoconch first three volutions are exposed. The Jr with three, rounded smooth whorls; teleoconch face is smooth and polished. Sto'tczK<J. with seven rounded whorls. Sculpture of shell ( 1868, p. 34, pl. 2, figs. 18-20 l rec or dE d t ~~ consisting of numerous axial ribs; first whorl species from the Trichinopolv < rd with 30 axial, rounded, prosocline ribs; inter­ Arrialoor Groups (Maastrichban of Sm.. th spaces as wide as ribs. On next whorls ribs India. These specimens are more infla.. t•d lessen, on one whorl 14, on the next 12, with and they have neither tubercies, l'f•r interspaces wider than ribs. On last whorl ribs nodes, nor axial ribs. disappearing, with shell practically smooth. Rostellaria palliata Forbes also hu. ht•f'n Weak spiral ribs present on spire, being more reported from the Maa~tnchtiar dPd pronounced near suture. Suture impressed. Danian from Tunisia, ~orth A~'ric..t Aperture not preserved in any specimen. Callus (Pervinquiere, 1912, p. 30. pl. 2. fig'. 12- covering entire surface of shell. Canal extending 16); from the Senonian of .'Wadar,asc<J." as upward, forming a curved channel through the Rostellaria (Calyptraphorus) pullzata callus, not covering first three whorls of spire; Forbes (Cottreau, 1922, p. 161, pl 1;), figs. then curving downward. Callus irregularly 16-19); and from the Upper Creh1ceous o~' thickened on either side of groove. The most dis­ Madagascar (Basse, 1932, p. 168. 1933, pt. tinctive feature of the species being the pres­ 10, figs. 11-13) as Rostellarirr. rC'yclomnl­ ence of two nodes on the body whorl, one near ops) palliata Forbes. aperture and another near the canal. No sculp­ From the Maastnchtian of ,Jamaica, ture on the side of body whorl opposite the Trechmann (1927, p. 39, pl. 4, fig 29, nodes, with exception of spiral striae near described Rostellaria (('alvptraphorus) sp , suture. on the basis of an incomplete specimen, Holotype: IGM 5887, height 32.5 mm, diame­ with only some badly prt'served whorls of ter 17.4 mm. the spire but the callus may be seen. It Paratype: IGM 5888, height 29.2 mm, diame­ does not show sculpture. Sohl { 1987, p. ter 19.8 mm. 1101) also mentioned a new :'ipeCie::- of Type locality: IGM 2448; 125 km south of Calyptraphorus from the Maastrichtian of Mexico City, near the borderline between the Ducketts Crossroads Area of J amaic, , states of Puebla, Morelos, and Guerrero. Access without any description. from Mexico City is via Highway 95, Mexico­ Our material differs from Calyptrapho Acapulco. About 5 km beyond Iguala, Guerrero, rus hopkinsi Olsson ( 1934, p. 68, pl. 10, a crossroad leads to Atenango del Rio. From this fig. 2; 1944, p. 96, pl. 15, figs. 8, 12) from point, a dirt road to the northeast passes beside the Monte Grande Formation fL'pper Texmalac. About 5.5 km beyond Texmalac, a Cretaceous) in Monte Grande, northwest roadcut on the left side exposes bright brown ern Peru. These specimens are not whoily marls, with a diverse molluscan fauna. The covered by the callus. The first whorls of locality is registered in the Locality Catalogus the spire have axial ribs that disappear of the Museo de Paleontologia of the Instituto and the surface of the whorl becomes de Geologia , at the Universidad Nacional smooth. The body whorl does not develop Auton6ma de Mexico (UNAM). nodes. Occ urrence: Mexcala Formation. Mexico; From the Gramame FormatiOn, lower Maastrichtian. Pernambuco, Brasil, Muniz (1993, p. 128, Etymology: The name of the species is based pl. 11 , figs. 5, 8) described Calyptraphorus 122 Tulane Studies in Geology and Paleontology Vol.