A NEW NEAR-SHORE MARINE FAUNA AND FLORA FROM THE EARLY NEOGENE OF NORTHWESTERN VENEZUELA

957

J. Paleont., 74(5), 2000, pp. 957–968Copyright q 2000, The Paleontological Society0022-3360/00/0074-957$03.00

A NEW NEAR-SHORE MARINE FAUNA AND FLORA FROM THE EARLYNEOGENE OF NORTHWESTERN VENEZUELA

M. R. SANCHEZ-VILLAGRA,1 R. J. BURNHAM,2 D. C. CAMPBELL,3 R. M. FELDMANN,4 E. S. GAFFNEY,5 R. F. KAY,6

R. LOZSAN,7 R. PURDY,8 AND J. G. M. THEWISSEN9

1Universitat Tubingen, Spezielle Zoologie, Auf der Morgenstelle 28, D-72076, Germany ,[email protected].,2Museum of Paleontology, University of Michigan, Ann Arbor, 48109-1079, USA,

3Department of Geological Sciences, University of North Carolina at Chapel Hill, Chapel Hill, 27599-3315, USA,4Department of Geology, Kent State University, Kent, Ohio 44242, USA,

5Department of Vertebrate Paleontology, American Museum of Natural History, New York, New York 10024-5192, USA,6Department of Biological Anthropology and Anatomy, Duke University Medical Center, Box 3170, Durham, North Carolina 27710, USA,

7Centro de Excursionismo Cientıfico del Estado Lara, Barquisimeto, Venezuela,8Department of Paleobiology, Smithsonian Institution, National Museum of Natural History, Washington DC 20560, USA,

9NEOUCOM—Anatomy, 4209 State Route 44, P.O. Box 95, Rootstown, Ohio 44272, USA

ABSTRACT—A diverse near-shore marine fauna existed during the early Miocene in what is today an arid inland region about 90 kmsouth of the Caribbean coast of northern Venezuela, a poorly known area geologically and paleontologically. The fossil locality consistsof more than 100 m of section exposed in an area of about 1 km2. We report the discovery of 20 molluscan species, one crab (Portunusoblongus), at least three sharks (Hemipristis serra and Carcharhinus spp.), one turtle (‘‘Podocnemis’’ venezuelensis), one crocodile(Crocodylidae), two whales (Odontoceti) and a three dimensional cast of the mesocarp or endocarp of a palm fruit. Several taxa arereported for the first time in Venezuela or in northern South America. The fauna indicates, or at least is consistent with, an earlyMiocene age for the locality, and a near-shore and shallow water marine depositional environment. We suggest that the earliest mammalpreviously reported from Venezuela, the pyrothere Proticia venezuelensis, was collected in Miocene rocks of the Castillo Formationinstead of Eocene rocks of the Trujillo Formation.

INTRODUCTION

KNOWLEDGE OF the early and middle Cenozoic fauna ofnorthern South America is of central importance in testing

hypotheses of Caribbean paleobiogeography (Iturralde-Vinentand MacPhee, 1999), as well as of fluvial history (Hoorn et al.,1995; Dıaz de Gamero, 1996; Lundberg et al., 1998), however,little is known about the fossil record in this part of the conti-nent. In Colombia, an important middle Miocene continental de-posit has been recently reviewed (Kay et al., 1997). In Vene-zuela, the locality of Urumaco, perhaps of middle to late Mio-cene age (Dıaz de Gamero and Linares, 1989), is the most im-portant locality in this regard (Lundberg et al., 1988;Sanchez-Villagra et al., 1995). Earlier vertebrate fossil depositsin Northwestern Venezuela have not been reported, except forthe supposedly Eocene locality of Proticia venezuelensis, anenigmatic pyrothere mammal described by Patterson (1977).Proticia venezuelensis was found in the southern flank of theSerranıa de la Baragua, Lara State, an unexplored area with ex-tensive exposures of Cenozoic rocks (Gonzalez de Juana et al.,1970).

In July, 1995, an expedition from Duke University consistingof RFK, R. H. Madden and MRSV prospected for fossil verte-brates in several areas of northwestern Venezuela. A short visitto some areas of the Serranıa de La Baragua was carried outwith RL. Here we report the discovery by RL of new faunal andfloral elements. Most of these fossils had been collected by RLbetween 1993 and 1995; the rest were collected on July 18,1995, by RFK, RHM, RL, and MRSV. The diversity of the faunaand flora reported here required multidisciplinary work for itsstudy; therefore, we have compiled the results of the taxonomicstudies by all of the authors, including DCC (molluscs), RJB(fruit), RMF (crabs), ESG (turtle), RP (sharks), and JGMT(whales). The aim of this work, in addition to the description offaunal remains, is to provide biostratigraphic and paleoecologicinformation for this new fossil locality in this relatively unex-plored area of NW Venezuela.

Abbreviations used in the text are: AMNH: American Mu-seum of Natural History; MBLUZ: Museo de Biologıa de la

Universidad del Zulia, Maracaibo; USNM: U. S. National Mu-seum of Natural History, Washington, D.C.

DESCRIPTION OF THE LOCALITY AND GEOLOGY

The locality, named Cerro La Cruz after the local name, con-sists of more than 100 m of section exposed in an area of about1 km2. Cerro La Cruz is found on the southern flank of theSerranıa La Baragua, in the NW area of Lara State, aproximately4 km NW from Caserıo La Mesa (Fig. 1). It can be reached bythe road between La Mesa and San Jacinto. Coordinates for thesite are, approximately, latitude 108229N, longitude 708039W.

Geology.The fossils were found in a well-exposed sectionof the Castillo Formation. The Castillo Formation was namedby Wheeler (1960, 1963) after the Cerro Castillo, about 27 kmsouth of Dabajuro, Distrito Buchivacoa, Estado Falcon. It wasused to designate the stratigraphic sequence on the western edgeof the Cuenca de Falcon. The Castillo Formation is exposed ina semicircular area along the western edge of the Cuenca deFalcon and disappears toward the center of the Cuenca. Accord-ing to Wheeler (1960), the fauna of the type locality of CastilloFormation indicates a late Oligocene age, while sections southof this locality also include younger rocks, extending to the earlyMiocene. Cati et al. (1968) considered the entire Castillo For-mation to be of early Miocene age. As discussed below, mostof the fossils indicate an early Miocene age for the Cerro LaCruz section. In the vicinity of the fossil locality, the CastilloFormation lies unconformably over Eocene rocks of the MisoaFormation (Wheeler, 1960, 1963; Patterson, 1977; Stephan,1977). However, the contact of the Castillo Formation with theoverlying or underlying formations cannot be seen at Cerro LaCruz. About 500 m northward from Cerro La Cruz, the under-lying Eocene Misoa Formation is exposed, consisting of mostlygrey shales with some marine fossils.

The exposure at the locality where the fossils were foundconsists of ca. 87 m of clayey marls interbedded with numerousthin (,1 m thick) hardground units. The strate are underlain andoverlain by sandstones, and the upper 15 m are gypsiferous. The

958 JOURNAL OF PALEONTOLOGY, V. 74, NO. 5, 2000

FIGURE 1—Location map of the Cerro La Cruz locality, near CaserıoLa Mesa, in the southern flank of the Serranıa La Baragua, NW LaraState, Venezuela. Scale 5 3 km.

strike of the strata is N 858E; the dip (determined in the bottom-most layer) is 498N. The strata are steeply dipping and morethan 100 m of section are exposed in an area of about 1 km2.Some of the sandstones are cross-bedded. Most fossils reportedhere were collected near the base of the exposures, however, theturtle skull (see below) was collected from the top.

SELECTED SYSTEMATIC PALEONTOLOGY

Information on the Phylum Mollusca is presented in Table 1.The sample, illustrated in Figure 2, includes seven taxa hithertonot reported for Venezuela, and provides biostratigraphic data(in addition, the Mollusca material also includes a scaphopod,and unidentified bivalves and gastropods). The rest of the taxaare treated below.

Order DECAPODA Latreille, 1803Infraorder BRACHYURA Latreille, 1803Section HETEROTREMATA Guinot, 1977

Superfamily PORTUNOIDEA Rafinesque, 1815Family PORTUNIDAE Rafinesque, 1815

Genus PORTUNUS Weber, 1795PORTUNUS OBLONGUS Rathbun, 1920

Figure 3

Material examined.Five specimens, including two exhibit-ing part of the right side of carapaces and portions of the ster-num and abdomen, USNM 490551 and 490552, and three spec-imens of chelae, USNM 490553–490555.

Discussion.The five specimens referred to this species areall fragmentary; however, each displays some characters thatconfirm the assignment of the material to Portunus oblongus.The holotype, USNM 328229, and additional specimens as-signed to the species by Collins and Morris (1976), possess acombination of characters that readily separate the species fromothers known from the region. The material from Venezuela ex-hibits several of these features. The frontal margin bears fourspines, the medial two of which extend slightly in advance ofthe lateral pair. The orbital rim is relatively distinct and, althoughonly the portion lying between the front and the innermost fis-sure is preserved, the rim is strongly curved near the front andbecomes quite straight over most of its length. The total numberof anterolateral spines cannot be determined; however, the pos-terior-most spines are large, forming nearly equilateral triangles.The spines are upturned and have weakly concave anterior andconvex posterior margins. Although the sternum is well exposed,there are no characteristics that are diagnostic of the species.The relative proportions of the chelae, and the development ofridges on the carpus and propodus, closely conform to thosedescribed by Collins and Morris (1976, pl. 20, figs. 7, 8).

Portunus oblongus was originally described from the earlyMiocene Cercado Formation, Province of Santiago, DominicanRepublic (Rathbun, 1920, p. 383). Subsequently, specimens col-lected from the middle Miocene Brasso Formation, ManzanillaBay, Trinidad, were referred to the species (Collins and Morris,1976, p. 121); therefore, this report represents the first record ofthe species in Venezuela. The material suggests an early to mid-dle Miocene age.

The genus is well represented in Tertiary sediments in andaround the Caribbean. Portunus (Portunus) haitensis Rathbun,1923, from the early Miocene of Haiti, has a carapace with muchhigher relief, a front which apparently projects much farther inadvance of the orbits, a very weak orbital ridge, and chelae withpalms nearly as high as long. Collins and Morris (1976) rec-ognized a close similarity between P. oblongus and P. gabbi,from the early Miocene of the Dominican Republic. In additionto the points noted by them, the present specimens exhibit apattern of ridges on the outer surface of the manus that differsfrom that seen in P. gabbi. The early and medial ridges on P.oblongus join near the proximal corner of the hand, whereasthose on the hand of P. gabbi are distinctly separated along theirentire length. Another species, P. tenuis Rathbun, 1918, was alsonamed for the early Miocene of Haiti; however, it was based

959SANCHEZ-VILLAGRA ET AL.—NEW NEOGENE ASSEMBLAGE FROM VENEZUELA

TABLE 1—Molluscs from Cerro La Cruz. If some age ranges have previously been listed only as ‘Oligocene-Miocene’ or ‘Miocene’ without more specificdata, the vague date is retained as well as any more specific ones to indicate uncertainty about the total range. PVMR: Prior Venezuelan Miocene record.Some earlier publications named forms of merely varietal status as distinct taxa, and have been later synonymized as indicated here. We recognize thesynonymies of Glyptoactis quirosana venezuelana, Chione montanitensis, Chione buchivacoa, Turritella montanitensis olcotti, and Turritella montanitensissaladilloensis with the respective appropriate names for the first time. Glyptoactis (Glyptoactis) quirosana includes Glyptoactis quirosana venezuelana (F.Hodson, 1927 in Hodson et al., 1927). Psammacoma gatunensis includes Psammacoma falconensis H. K. Hodson, 1931 in Hodson and Hodson, 1931a.Cyclinella cyclica includes Cyclinella venezuelana H. K. Hodson, 1927 in Hodson et al., 1927. Chionopsis tegulum includes Chione (Chione) montanitensisH. K. Hodson, 1927 in Hodson et al., 1927, Chione (Chione) paraguanensis H. K. Hodson, 1927 in Hodson et al., 1927, and Chione (Chione) buchivacoaH. K. Hodson, 1927 in Hodson et al., 1927. Liromissus quirosensis includes Liromissus quirosensis querulana H. K. Hodson, 1927 in Hodson et al., 1927.Turritella montanitensis includes Turritella montanitensis olcotti F. Hodson, 1926, and Turritella montanitensis saladilloensis F. Hodson, 1926. ‘Turritella’venezuelana includes Turritella venezuelana quirosana F. Hodson, 1926, and Turritella venezuelana watkinsi F. Hodson, 1926. References used in identifyingmollusks and establishing their ranges include: Dall, 1890–1903; Hubbard, 1920; Gardner, 1925–1950; Hodson, 1926; Hodson et al., 1927; Woodring, 1927,1957–1982; Hodson and Hodson, 1931a, 1931b; Hedberg, 1937; Wheeler, 1963; Jung, 1965; Palmer and Brann, 1965; Dıaz de Gamero, 1968; Vokes, 1977,1986; Gibson-Smith and Gibson-Smith, 1979, 1983; Waller, 1991; and Roopnarine, 1996, 1997.

TaxonPrevious records

(age)Spec. #

MBLUZ-P PVMR

Saccella gracillima Jung, 1965 early Miocene 1861 yesBrachidontes (Brachidontes) sp. cf. B. grammatus Dall, 1898 early Miocene 1862 noAnadara mirandana (H. K. Hodson, 1927 in Hodson et al., 1927) ‘Olig.-Mio.’, early Miocene 1863 yesEuvola burnsi Dall, 1898 early Miocene (late Burdigalian) 1864 nocf. Ostrea sp. cf. ‘Ostrea podagrina Dall, 1896’ of Gardner, 1926

not of Dall, 1896early Miocene (late Burdigalian) 1865 no

Cubitostrea pauciplicata (Dall, 1898) late early to early middle Miocene 1866 noGlyptoactis (Glyptoactis) quirosana (F. Hodson, 1927 in Hodson et

al., 1927)‘Olig.-Mio.’, ‘middle Miocene’ (tentative) 1867 yes

Trachycardium sp. cf. ‘Trachycardium’ virile Dall, 1900 early Miocene (late Burdigalian) 1868 noPsammacoma gatunensis (Toula, 1909) early to late Miocene 1869 yesSemele sp. cf. S. zuliana H. K. Hodson, 1931 in Hodson and Hod-

son, 1931aearly Miocene 1870 yes

Tagelus sp. cf. ‘Tagelus (Mesopleura) sp. cf. T. divisus (Speng-ler)’ of Gardner, 1928

early to middle Miocene 1871 no

Agripoma (Pitarella) paraguanensis (H. K. Hodson, 1927 in Hod-son et al., 1927)

early Miocene 1872 yes

Cyclinella cyclica (Guppy, 1866) early to late Miocene 1873 yesClementia (Clementia) dariena dariena (Conrad, 1855) early to late Miocene 1874 yesChionopsis tegulum (Brown and Pilsbry, 1911) ‘Olig.-Mio.’, early to middle Miocene 1875 yesLiromissus quirosensis (H. K. Hodson, 1927 in Hodson et al.,

1927)‘Olig.-Mio.’, early Miocene 1876 yes

Lithopoma portoricoensis (Hubbard, 1920) early Miocene 1877 no‘Turritella’ montanitensis F. Hodson, 1926 ‘Olig.-Mio.’, early Miocene 1878 yes‘Turritella’ venezuelana F. Hodson, 1926 Miocene, early Miocene 1879 yesMelongena venezuelana Gibson-Smith and Gibson-Smith, 1983 e. Mioc. (Burdigalian and ? Aquitanian) 1880 yes

upon isolated fingers and cannot be compared to the other Mio-cene members of the genus.

Order CARCHARHINIFORMES Compagno, 1973Family HEMIGALEIDAE Hasse, 1879HEMIPRISTIS SERRA Agassiz, 1835

Figure 4

Material examined.The material consists of an upper an-terolateral tooth missing a portion of the mesial root lobe(MBLUZ-P-1881), and the mid-portion of a crown missing thetip and root (MBLUZ-P-1882).

Discussion.MBLUZ-P-1881 compares favorably with thejuvenile teeth of Hemipristis serra, a species common in themiddle Miocene (Cappeta, 1987). In the juvenile teeth, the ser-rations on the mesial side of the crown are not as coarse as theyare in adult teeth. This tooth measures 13.4 mm in height and14.0 in width. MBLUZ-P-1882 is larger and is from a largerindividual, both in its size and by the fact that the mesial ser-rations are coarse. Its measurements are: height 5 9.4 mm;width 5 11.4 mm.

Hemipristis serra is common in Miocene sediments world-wide. Its living relative H. elongatus inhabits tropical coastalwaters down to depths of 30 m in the Indian Ocean and south-west Pacific Ocean. The extant species feeds on bony fishes andsharks (Compagno, 1984).

Family CARCHARHINIDAE Jordan and Evermann, 1896CARCHARHINUS cf. OBSCURUS LeSuer, 1818

Figure 4Material examined.MBLUZ-P-1883, an upper anteropos-

terior tooth missing a portion of the mesial root lobe.Discussion.This specimen is darker in color and more

abraded than the other shark teeth, which suggests it may havebeen transported for some distance and/or laid on the sea floorfor a while before burial. The low crown of this tooth and thestrong convexity of the mesial edge suggest that it is C. obscurusrather than C. leucas with which its teeth can be confused. Theteeth of C. obscurus have been identified from Miocene sedi-ments of North America (Applegate, 1986). Its measurementsare: height 5 14.3 mm; width 5 10.3 mm. According to Com-pagno (1984), C. leucas inhabits warm-temperate to tropicalcoastal waters from the surface to 400 m. It feeds on bony fishes,sharks and invertebrates.

CARCHARHINUS cf. PEREZI Poey, 1876Figure 4

Material examined.MBLUZ-P-1884, an upper anteropos-terior tooth lacking root, crownfoot and orthodentine core.

Discussion.This tooth compares favorably with the upperanteroposterior teeth of Carcharhinus perezi; however, since animportant portion of MBLUZ-P-1884 is missing, this identifi-cation is tentative. C. perezi has been reported from the late earlyMiocene of Delaware based on dental remains (Purdy, 1998).


FIGURE 2—1, Saccella gracillima, MBLUZ-P-1861, length 13 mm. 2, Anadara mirandana, MBLUZ-P-1863A, length 21 mm. 3, Euvola burnsi,MBLUZ-P-1864, width 13 mm. 4, cf. Ostrea sp., MBLUZ-P-1865, height 63 mm. 5, 6, Cubitostrea pauciplicata, MBLUZ-P-1866A, maximumradial length 34 mm; MBLUZ-P-1866B, maximum radial length 37 mm. 7, Trachycardium sp., MBLUZ-P-1868, height 30 mm. 8, Glyptoactis(Glyptoactis) quirosana, MBLUZ-P-1867, length 20 mm. 9, Psammacoma gatunensis, MBLUZ-P-1869, length 35 mm. 10, Semele sp., MBLUZ-P-1870, length 25 mm. 11, Tagelus sp., MBLUZ-P-1871, length 26 mm. 12, Agripoma (Pitarella) paraguanensis, MBLUZ-P-1872, length 51mm. 13, Cyclinella cyclica, MBLUZ-P-1873, height 31 mm. 14, Clementia (Clementia) dariena dariena, MBLUZ-P-1874, height 46 mm. 15,Chionopsis tegulum, MBLUZ-P-1875, length 35 mm. 16, Liromissus quirosensis, MBLUZ-P-1876, length 28 mm. 17, Lithopoma portoricoensis,MBLUZ-P-1877, height 15 mm. 18, ‘‘Turritella’’ montanitensis, MBLUZ-P-1878, height 39 mm. 19, ‘‘Turritella’’ venezuelana, MBLUZ-P-1879, height 21 mm. 20, Melongena venezuelana, MBLUZ-P-1880, height 72 mm. All dimensions are unreconstructed.


FIGURE 3—Portunus oblongus. 1, Dorsal view of broken carapace, USNM-490551, showing the posteriormost anterolateral spines; 2, 3, outerand upper views of carpus and propodus, USNM-490553; 4, 5, ventral and dorsal view of broken carapace, USNM-490552, showing a nearlycomplete sternum and partially preserved fronto-orbital margin. Dimensions: 1: reconstructed width 5 51 mm, reconstructed length 5 26 mm;2: maximum preserved length 5 36 mm, maximum preserved width 5 16 mm, 3: maximum preserved length 5 38 mm, maximum preservedwidth 5 12.7; 4: middle preserved length 5 25 mm, middle preserved width 5 38 mm.

The extant C. perezi inhabits Caribbean tropical inshore watersto a depth of 30 m; it feeds on bony fishes (Compagno, 1984).

In addition to the Chondrichthyes reported in this section, twofurther specimens are catalogued: a batoid tail spine (MBLUZ-P-1886, Myliobatiformes, Fig. 4) and the basal portion of anupper anteroporsterior tooth of Carcharhinus sp. (MBLUZ-P-1885).

Order TESTUDINES Linnaeus, 1758Suborder PLEURODIRA Cope, 1864

Hyperfamily PELOMEDUSOIDES Cope, 1868aFamily PODOCNEMIDIDAE Cope, 1868b

genus indet, cf. ‘‘PODOCNEMIS’’ VENEZUELENSIS Wood andDıaz de Gamero, 1971

Figure 5

Material examined.A poorly preserved but nearly completeskull (AMNH-30,000; cast MBLUZ-P-1887).

Discussion.Wood and Dıaz de Gamero (1971) described anew species, Podocnemis venezuelensis, on the basis of shellmaterial from the Urumaco Formation of Falcon State, Vene-zuela. Subsequent work by both Venezuelan geologists and a1972 Harvard expedition under the direction of R. C. Woodresulted in the association of several well preserved skulls withP. venezuelensis shells, showing that this species was not as-signable to Podocnemis (Diaz de Gamero and Linares, 1989).Work in progress by R. C. Wood and ESG (see Wood and Gaff-ney, 1989; Gaffney et al., 1996) suggests that P. venezuelensis

belongs, together with an undescribed species from the Oligo-cene of Puerto Rico (AMNH-27,222), in a genus being de-scribed by R. C. Wood and ESG. The new skull probably be-longs in this genus because it shares with the Puerto Rican spe-cies and P. venezuelensis a large palatal convexity on the sec-ondary palate, a condition unique to these taxa.

The broader relationships of AMNH-30,000 are readily de-termined. The skull has the typical pleurodiran processus troch-learis pterygoidei well preserved on the left side. The basicran-ium shows the enlarged pterygoid (‘‘carotid’’) tunnel character-istic of the Podocnemididae of Broin (1988) and Meylan (1996).Within the Podocnemididae the Castillo skull has the broad sec-ondary palate with a midline cleft that is unique to the Stereo-genys-Shweboemys group (Gaffney et al., 1996). This group (seeBroin, 1988, for references) includes Stereogenys cromeri fromthe Eocene of Egypt, Shweboemys pilgrimi from the Pliocene ofBurma, ‘‘Shweboemys’’ gaffneyi from the Miocene of Pakistan,Shweboemys antiqua from the Eocene of Egypt, as well as anew taxon from the Oligocene of Puerto Rico (Gaffney et al.,1996). This monophyletic group is defined by a series of derivedcharacters and occurs in North Africa, Asia, and the circum-Caribbean.

Within the Shweboemys group, AMNH-30,000 is most closelyrelated to the other Caribbean taxa, i.e., ‘‘Podocnemis’’ vene-zuelensis and the new Puerto Rican form, but the species mostclosely related to these taxa are all North African.

This new skull (AMNH-30,000) could possibly represent anew species or it could belong to ‘‘Podocnemis’’ venezuelensis.The new skull differs from the undescribed Puerto Rican speciesand from ‘‘Podocnemis’’ venezuelensis in being flatter in profile


FIGURE 4—1–4, Hemipristis serra; 1, 2, MBLUZ-P-1881, 3, 4,MBLUZ-P-1882. 5, 6, Carcharhinus cf. obscurus, MBLUZ-P-1883.7, 8, Carcharhinus cf. perezi, MBLUZ-P-1884. 9, 10, Myliobatifor-mes, MBLUZ-P-1886. Dimensions: MBLUZ-P-1881: height 5 13.4mm; width 5 14.0; MBLUZ-P-1882: height 5 9.4 mm; width 5 11.4mm; MBLUZ-P-1883: height 5 14.3 mm; width 5 10.3 mm;MBLUZ-P-1884: height 5 1,1; width 5 7.6 mm; MBLUZ-P-1886:length 5 15 mm; width 5 5.8 mm.

FIGURE 5—1, Ventral and 2, dorsal views of the skull of ‘‘Podocnemis’’cf. venezuelensis (AMNH-30,000). Dimensions: total length on mid-line 5 92 mm, maximum width 5 82 mm, maximum height 5 53mm.

and in having a less arched snout region, differences that maybe the result of preservation. The poor condition of the skullprecludes determination of other possibly significant characters.The bone surface of the skull has been eroded off, and only afew sutures are visible.

Order CROCODYLIFORMES Benton and Clark, 1988Family CROCODYLIDAE Gmelin, 1788

Crocodylia indeterminate

Material examined.An isolated dorsal osteoderm (MBLUZ-P-1888).

Discussion.Reference to Crocodylia is supported by the factthat the only non-crocodylian crocodylomorphs known from Ol-igocene or Miocene strata, members of the family Sebecidae,have unusual scutes with smooth dorsal margins (Busbey, 1986),whereas the present specimen shows the pitted dorsal surfacetypical of crocodylians. The large size of the specimen, alongwith the depositional environment, suggest possible reference toGavialosuchus americanus (Sellards, 1915), a large Miocene-Pliocene (Barstovian to Hemphillian) estuarine and marine cro-codylian from eastern North America (Morgan, 1986). An earlyMiocene record from Venezuela would represent a temporal andgeographical range extension for this species, but this is just apreliminary hypothesis, given the incompleteness of the presentmaterial.

Order CETACEA Brisson, 1762Suborder ODONTOCETI Flower, 1864

Incerti familiae (‘‘Squalodontid’’)aff. PROSQUALODON AUSTRALIS Lydekker, 1894

Figure 6Description.Body of both vertebrae oval in cross-section

with a somewhat flattened dorsal outline. Rostral and caudalepiphyses fused to the diaphysis, but epiphyseal lines are stillvisible. No rib facets on the body of either vertebra. Neural canal


FIGURE 6—1, 2, Lateral (anterior is to right) and 3, 4, posterior viewsof thoracic vertebrae of squalodontid aff. Prosqualodon australis (1,3: MBLUZ-P-1890; 2, 4: MBLUZ-P-1889). Dimensions: MBLUZ-P-1889—body length 5 46 mm (measured ventrally), body width 543 mm (measured anteriorly), body height 5 34 mm; MBLUZ-P-1890:—body length 5 49 mm, body width 5 44 mm, body height5 36 mm.

of MBLUZ-P-1889 and MBLUZ-P-1890 narrower than body;arrangement of laminae, articular processes, and spinous pro-cesses is similar. Articular processes flattened mediolaterally,projecting rostrolaterally and each bearing an articular facet onthe medial side. This facet is concave mediolaterally in bothvertebrae. Articular process of MBLUZ-P-1889 projects furtherrostrally than in MBLUZ-P-1890. Articular facet more elongateand flatter rostrocaudally; its surface is somewhat irregular inMBLUZ-P-1889 (right side, left side is not preserved). Spinousprocesses of both vertebrae attach to the entire length of lamina,projecting caudally and taper strongly toward apex. Left andright posterior articular facets much closer than anterior articularfacets in MBLUZ-P-1889. Pedicles restricted to the anterior partof the body in both vertebrae. In MBLUZ-P-1889, two trans-verse processes project laterally from each side of vertebra.More ventral process is small, lacks a facet, and projects fromjunction of body and pedicle. More dorsal facet is larger, bearsa concave facet for a rib, and projects from junction of pedicleand lamina. These two processes form a rostrocaudally directednotch lateral to the body. This notch forms a rostro-caudally

directed canal and lacks a lateral bony wall. In MBLUZ-P-1890,there is only a single lateral process, larger than either processon MBLUZ-P-1889. Process of MBLUZ-P-1890 bears a con-cave facet for a rib at its end, and projects from lateral side ofthe body and from base of pedicle. Rostral part of this processbears a mediolateral groove. Caudal part bears a depression inlocation of foramen in MBLUZ-P-1889.

Dimensions.MBLUZ-P-1889—body length 5 46 mm(measured ventrally); body width 5 43 mm (measured anteri-orly); body height 5 34 mm; total width 5 38 mm (since onetransverse process is missing, this measurement represents thevalue of the right half doubled); approximate total height 5 100mm (spinous process length estimated); maximum width of neu-ral canal 5 28 mm; maximum height of neural canal 5 20 mm.MBLUZ-P-1890—body length 5 49 mm; body width 5 44 mm;body height 5 36 mm; total width 5 80 mm; maximum widthof neural canal 5 29 mm; maximum height of neural canal 521 mm.

Material examined.Two posterior thoracic vertebrae, pos-sibly subsequent vertebrae of the same individual. MBLUZ-P-1889 is a more anterior element than MBLUZ-P-1890. MBLUZ-P-1889 lacks the tip of the spinous process and the left trans-verse process and articular process. MBLUZ-P-1890 lacks mostof the spinous process and all of the posterior articular facets.

Discussion.Comparisons of the Cerro La Cruz vertebraewith those of other mid-Cenozoic cetaceans are necessarily lim-ited, because posterior thoracic vertebrae are known for only afew described species and these commonly have been describedin a cursory fashion only. However, the thoracolumbar part ofthe vertebral column varies significantly among cetaceans andis fairly diagnostic at higher taxonomic levels.

Slijper (1936) described in detail the vertebral morphology ofcetaceans, identifying three types of posterior thoracic vertebraethat are clearly distinct in the serial homology of their transverseprocesses. Filler (1986) discussed the transverse processes ofcetacean vertebrae while cautioning against a typological con-cept of serial homology, but Slijper’s analysis is still useful froma descriptive point of view. Of Slijper’s three types, the CerroLa Cruz vertebrae pertain to the ziphoid type. In this type, thejoints for costal capitulum and diaphysis lie on processes thatare often connected distally, leaving a deep groove or completecanal on the lateral side of the vertebral body. Slijper (1936)noted that this type of vertebra occurs in fossil Eurhinodelphi-dae, Notocetus vanbenedeni (Slijper’s Diochotichus) and Pros-qualodon australis, as well as in extant physeteroids and zi-phiids.

There are few well-preserved eurhinodelphid vertebrae olderthan middle Miocene. Lydekker (1892) described a caudal ver-tebra of Iniopsis caucasus, but no thoracic and lumbar vertebraeare known for this species. The rich eurhinodelphid sample fromthe Antwerp region includes a few well-preserved posterior tho-racic vertebrae (Slijper, 1936). These specimens (from the Mio-cene-Pliocene boundary) are so far removed temporally and geo-graphically from the Venezuelan specimens that a comparisonseems inconsequential. Eurhinodelphids are known from the Ol-igocene and Miocene, and may have had a worldwide distribu-tion, but additional material is necessary to make a comparisonuseful.

Posterior thoracic vertebrae of Notocetus vanbenedeni fromthe early Miocene of Patagonia were described by True (1910b)and Cabrera (1926), and the species is commonly considered asqualodelphid as discussed by de Muizon (1987). Although theVenezuelan vertebrae are similar in arrangement of the trans-verse process, Notocetus vertebrae have a more rounded bodyand dorsoventrally elongate neural canal than MBLUZ-P-1889and MBLUZ-P-1890. If the vertebral morphology of Notocetus


FIGURE 7—1, Lateral and 2, dorsal views of Arecaceae (Palmae), Ge-nus, species indet. (MBLUZ-P-1892). Dimensions: length 5 55 mm;circumference 5 135 mm; width 5 38 and 35 mm on different axes.

is typical for squalodelphids, then it is unlikely that MBLUZ-P-1889 and MBLUZ-P-1890 represent this family.

The earliest physeteroids are known from the late Oligocene,but little vertebral material is known for these. The morphologyof the modern species differs from that of the Cerro La Cruzvertebrae. In overall shape of the transverse processes, MBLUZ-P-1889 and MBLUZ-P-1890 resemble modern physeteroidsclosely, but they differ in the shape of the vertebral body andneural canal. The vertebral body is narrower and higher in phy-seteroids and the neural canal is narrower. If these features areconsistent within physeteroids, it is unlikely that MBLUZ-P-1889 and MBLUZ-P-1890 can be assigned to the Physeteroidea.

It is also unlikely that the Cerro La Cruz vertebrae representa ziphiid, as this family ranges back only to the middle Miocene(Fordyce and Barnes, 1994). Morphologically, MBLUZ-P-1889and MBLUZ-P-1890 are different from modern ziphiid vertebraein such features as the size of the spinous process (as describedby True, 1910a).

The Cerro La Cruz vertebrae are more similar to those de-scribed for Prosqualodon australis. True (1909) described twoposterior thoracic vertebrae with mediolaterally elongated ver-tebral bodies and a dorsoventrally low neural canal, similar toMBLUZ-P-1889 and MBLUZ-P-1890. These vertebrae aresmaller than posterior thoracics of Prosqualodon australis.MBLUZ-P-1889 and MBLUZ-P-1890 are from vertebral levelsmore anterior than those of Prosqualodon australis and are thusdifferent in the morphology of the transverse processes. EarlyMiocene Prosqualodon australis has uncertain affinities; it wasidentified as an enigmatic member of the poorly defined squal-odontid-group by Fordyce and Barnes (1994). There are no fea-tures that argue against allocation of the Venezuelan vertebraeto Prosqualodon australis, but comparisons are so limited thatthis allocation cannot be evaluated critically. Given the limitednumber of direct comparisons, it is best to refer the Venezuelanmaterial tentatively to Prosqualodon australis. Further materialis needed to test this allocation.

One more probable cetacean vertebrae (MBLUZ-P-1891) wasdiscovered at Cerro La Cruz. It has a large vertebral body(length 5 62 mm; width 5 97 mm; height 5 95 mm; total width5 151 mm) with complete transverse processes and lacks theentire neural arch. The transverse process is extremely short,projecting barely beyond the anterior and posterior demifacetsfor articulation with the ribs which are located at its base. Theroot of the neural arch is attached to the dorsal part of the trans-verse processes and the body displays two strong ventral pro-cesses on either side of the sagittal plane. This vertebra is thatof a large cetacean, possibly similar in size to modern Caperea(based on measurements listed by Crovetto, 1991). The body isshort antero-posteriorly, as in modern balaenids, but the speci-men is too incomplete for confident identification.

Order ARECALES Novak, 1954Family ARECACEAE Schultz-Schultzenstein, 1832

Genus and species indeterminateFigure 7

Material examined.MBLUZ-P-1892. The specimen is athree dimensional cast of the mesocarp or endocarp of a palmfruit, preserved in a fine, sandy ironstone. Dimensions: length5 55 mm; circumference 5 135 mm; width 5 38 and 35 mmon different axes.

Discussion.The external surface structure of this specimenis of a finely fibrous texture, reflecting the fibers of the meso-carp. These fibers become thinner from the proximal to the distalportion of the fruit. During their course they anastomose slightly,crossing and parting away from the center line of each carpel.The fruit has three clear divisions to the ovary, running from

proximal to distal portion, reflecting the initially three-carpellatecondition. The number of seeds in the fruit is unknown (manypalm genera, although clearly three-carpellate, produce only asingle seed).

The generic assignment of this fruit is not certain at this time.There are three possibilities:

1. Attalea (which as recognized by Henderson, 1995, includesthe genera Scheelea and Orbigyna as well as Attalea sensustricto): a genus of about 30 species today found from Mex-ico to Paraguay. A recent revision (Henderson and Balick,1991) merged four previously distinct genera into the cur-rently recognized Attalea. The fossil differs from specimensof this genus in having much more strikingly defined carpeldivisions, but otherwise the fossil matches specimens in thegenus well. Attalea was previously reported by Berry (1929,1934) from the Eocene of Peru.

2. Astrocaryum: a genus of about 15 species that is found fromMexico to Bolivia and Brazil (Kahn and Millan, 1992). Sub-genera are based on characters not preserved in the fossilspecimen (Henderson, 1995). This genus is listed here be-cause of the similarity in form, size and fibres of the fruits.However Astrocaryum spp. normally bear three pores attheir distal end which would have been visible in this spec-imen had they been present.

3. Syagrus: is a genus of about 35 species, which is distributedtoday from Colombia to Bolivia and Brazil, with a concen-tration of species in the drier areas of Brazil. The speciesof this genus also bear pores at the distal end (Henderson,1995), so this has the same problem in comparison with thefossil as does Astrocaryum.

Sectioning of the fruit does not appear to be warranted at thistime as the specimen appears to be a cast, not a petrified spec-imen.

Other fossil remains.In addition to the taxa discussedabove, the collected invertebrate material includes scleractiniancorals and barnacles.

DISCUSSION

Age and paleoecology of the assemblage.The faunal ele-ments suggest or at least are consistent with an early Mioceneage. The age of the Castillo Formation was reported by Wheeler(1960, 1963) to be late Oligocene to early Miocene based onthe study of foraminifera and macroinvertebrates from a localityin Falcon State, north of the Cerro La Cruz locality.

Wheeler (1963) listed selected taxa from the Castillo For-mation. Of the nine molluscan taxa listed for the early Miocene,two (Turritella venezuelana and T. venezuelana quironosa) areherein considered synonymous. Four of the remaining eight werefound in the present study, and a fifth (Dentalium bocasenseOlsson, 1922) may be represented in the present collection by


worn, fragmentary material. Given the small size of the twosamples and the fact that these four species are among the mostabundant in the present material, it is very likely that Wheeler’ssamples were from the same part of the formation as the presentsample. None of the Oligocene taxa reported by Wheeler wasfound in the present collection.

Unfortunately, many early papers have presented vague oruncertain information concerning the stratigraphic provenanceof the molluscan species reported here. The stratigraphic settingof the collections described by Hodson (1926), Hodson et al.(1927), and Hodson and Hodson (1931a, 1931b) was proprietaryinformation. However, all taxa seem compatible with an earlyMiocene age assignment, correlating with previously studiedmollusk-rich deposits in northern Venezuela and Colombia(Jung, 1965; Gibson-Smith and Gibson-Smith, 1979, 1983). Thecrab genus Portunus ranges from Eocene to Recent (Glaessner,1969), and has been collected on all continents except Australiaand Antarctica. Concerning the sharks, the identifiable taxa havebroad stratigraphic ranges; Hemipristis serra extends from thelate Oligocene to the early Pleistocene, and the Carcharhinusspecimens identifiable to species range from the early Mioceneto Recent. Future studies of foraminifera from Cerro La Cruzshould provide additional information about this locality’s age.

Currently northwestern Lara State is arid, and its drainagebasins are small, with rivers of low, intermittent discharge. Incontrast, a near-shore marine depositional environment is sug-gested by the fossils in early Miocene times. The molluscanfauna indicates a calm-water environment with fine-grained sed-iment. Many Recent species in the same genera are confined toshallow tropical water of normal salinity. Almost all bivalvesremain paired, even shallow-burrowing or epifaunal forms suchas Glyptoactis and Anadara. This indicates autochthonous buri-al, as would perhaps be expected in a calm-water environment.However, there are also some pieces of coral which could reflectmixed substrates in the region, or they could be allochthonous.

The cosmopolitan crab genus Portunus embraces numerousRecent species of actively swimming crabs that are typicallyfound in shallow water habitats, often on sandy or coralline sub-strates (Rathbun, 1930), although Williams (1984) noted a fewspecies that ranged to depths of 550 m. If the ecological pref-erences of the shark taxa have not changed since the late Oli-gocene, they suggest that the Cerro La Cruz environment ofdeposition was a tropical shallow sea. The ecology of the turtlereported here is unclear; most representatives of the group occurin sediments that could be of nearshore or fluvio-lacustrine or-igin, but none is known from clearly offshore marine sediments.In conclusion, all faunal elements either suggest or are consistentwith a coastal marine environment of deposition.

On the age and provenance of Proticia venezuelensis, the old-est fossil mammal from Venezuela.Our discovery of the CerroLa Cruz fauna and prospecting in the vicinity of this locality hasimplications concerning the potential stratigraphic provenance ofthe oldest reported fossil mammal from Venezuela. Little isknown about this mammal and its provenance. Proticia vene-zuelensis was described by Patterson (1977) as a representativeof the Pyrotheria, an extinct order of ungulate-like mammals ofuncertain affinities (McKenna, 1980; Lucas, 1986). The speciesis represented by a jaw fragment with p3-m1. The fossil wascollected in 1964 by a second person, several years before Pat-terson visited the supposed locality in 1970. As related by Pat-terson (1977), the fossil was reported to be found in a spot alongthe Quebrada de Agua Viva, which is located about 13 km westof the Cerro La Cruz locality.

In 1995 RFK, RL, RHM and MRSV visited the purportedcollection spot of Proticia venezuelensis (Patterson, 1977), withthe help of Don Guillermo, a local resident who accompanied

Patterson in 1970 to the locality. We found no traces of anyvertebrate fossil in the area and, based on this observation (alsoexperienced by Patterson, 1977, p. 400), we suggest that theprovenance of P. venezuelensis should be put into question, anopinion already expressed by other authors. Based also on thestratigraphic position of other representatives of Pyrotheria (re-viewed in Lucas, 1986), Odreman Rivas and Medina (1984)suggested that it is unlikely that the fossil was found indeed inthe Trujillo Formation, but rather in the Santa Rita Formation,of later Eocene age. Actually, Proticia venezuelensis is morelikely to have come from the rocks of the Castillo Formation.Its dental anatomy places the phylogenetic position of this taxonin question. Cuspate tooth form (lack of bilophodonty) and pres-ence of thick enamel suggest sirenian affinities. This would cor-respond well with the kind of environment in which we suggestthis fossil was found.

Summary and conclusion.A diverse near-shore marine fau-na existed during the early Miocene in what is today an aridinland region about 90 km south from the Caribbean Coast ofnorthern Venezuela. Preliminary collection resulted in the dis-covery of 20 molluscan species, one crab, at least three sharks,one turtle, one crocodile, one whale and one palm fruit. Severalof these taxa suggest or at least are consistent with an earlyMiocene age for the deposit. Based on circumstantial evidence,we suggest that the earliest reported mammal from Venezuela,the pyrothere Proticia venezuelensis, was collected in Miocenerocks of the Castillo Formation.

Iturralde-Vinent and MacPhee (1999) proposed reconstruc-tions of the Caribbean paleogeography for late Oligocene (27–25 Ma) and for early middle Miocene (16–14 Ma) intervals thatbracket the age estimate for the assemblage reported here. Thechanges in the geographic area around Cerro La Cruz reportedby Iturralde-Vinent and MacPhee (1999) are minimal betweenthese two intervals. Cerro La Cruz represents a fauna from theshallow marine area of what is today the Falcon Basin, north ofthe fork of land that divided this area from the Orinoco Seaway(Iturralde-Vinent and MacPhee, 1999, figs. 7, 8).

Future exploration of the region surrounding Cerro La Cruzcould help to test hypotheses of Caribbean biogeography pro-posed by Iturralde-Vinent and MacPhee (1999). This will requirethe discovery of continental older rocks, which would corre-spond with the south-western GAARlandia, a continuous suba-real land-barrier including the Greater Antilles, the Aves Ridge,and the Falcon and Maracaibo basins. According to Iturralde-Vinent and MacPhee (1999), GAARlandia existed between thelatest Eocene and early Oligocene (35–33 Ma) and played animportant role in the dispersal of the biota that populated theGreater Antilles. Future studies in the Cerro La Cruz area couldyield possible ancestors of the endemic Caribbean fauna of de-batable biogeographic origin.

ACKNOWLEDGMENTS

This work was supported by a NSF Grant to RFK and R. H.Madden, and by a Tinker Research grant to RFK from the Centerfor Latinoamerican Studies of Duke University-University ofNorth Carolina at Chapel Hill. We thank J. Moody for facilitat-ing cataloging and preservation of most of the fossil material inMaracaibo, S. Zack for identifying the crocodilian remain andfor technical assistance, J. Jouval for providing important liter-ature, O. Odreman Rivas for his advice, R. Asher for commentson the manuscript, G. Schmid for technical assistance and R. H.Madden for his help in the field and in other aspects of thisproject. We thank S. K. Donovan, B. J. MacFadden and J. Todd


for their useful reviews, and T. Hazen and A. F. Budd for edi-torial remarks. Writing of this work was completed at the Lehrs-tuhl Zoologie of the Universitat Tubingen, which is lead by W.Maier.

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A NEW NEAR-SHORE MARINE FAUNA AND FLORA FROM THE EARLY NEOGENE OF NORTHWESTERN VENEZUELA