BIOGEOGRAPHY OF THE CUBAN OXFORDIAN HERPETOFAUNA

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1 BIOGEOGRAPHY OF THE CUBAN OXFORDIAN HERPETOFAUNA Zulma Gasparini Departamento Paleontología Vertebrados, Museo de La Plata, Paseo del Bosque s/n, 1900, La Plata, Argentina and Manuel A. Iturralde-Vinent Museo Nacional de Historia Natural, Obispo no. 61, Plaza de Armas, La Habana Vieja 10100, Cuba. ) Abstract The Oxfordian reptiles recorded in Cuba are the direct evidence of how the Caribbean Seaway acted as habitat and/or corridor for numerous pelagic predator groups, and even for those, as pterosaurs, that flew over the area searching for shoal. This paper is a synthesis of nearly twenty years of collecting and investigating the Cuban Jurassic reptiles. To the composition of the herpetofauna, partially already published, and updated in Appendix 1, remarks about the geologic setting, stratigraphic position, age, taphonomy, paleogeographic scenario and biogeographic relationships of the Cuban Oxfordian marine reptiles are added. The fossil found in the lower to middle Oxfordian Jagua Vieja Member of the Jagua Formation (Western Cuba) include marine invertebrates and fish, pterosaurs, terrestrial plants, and dinosaurs. Marine herps specimens are dominated by plesiosauroids (~53 %), but other groups such as ichthyosaurians (~12 %), marine crocodilians (~12 %), pliosauroids (~6 %), and turtle (~3 %) are present. Terrestrial reptiles are represented by pterosaurs (~12 %) and dinosaurs (~3 %). The abundance of plant remains (including trunks), pterosaurs, dinosaurs, and even a primitive pleurodiran turtle suggest a paleoenvironment not far from the coast. Other reptiles, off shore predators as plesiosaurs, pliosaurs, metriorhrynchids and ophthalmosaurians, probably crossed the Seaway in seasonal migrations. Keywords: Reptiles, Cuba, Oxfordian, Caribbean Seaway. Accronyms USNM and NMHN. U.S. National Museum of Natural History, Washington, DC. 1

2 AMNH. American Museum of Natural History, New York MNHNCu. Museo Nacional de Historia Natural, Cuba IGP. Instituto de Geología y Paleontología, La Habana, Cuba 1. Introduction Late in the XIX Century, the occurrence of Jurassic rocks dated with ammonites in Cuba was established by the Spaniard mining engineer Manuel Fernández de Castro (1876), and later obtained wide recognition after the report by the notorious Cuban naturalist Carlos De la Torre y Huerta (1912). They discovered abundant Jurassic ammonites from a locality named Abra or Puerta del Ancón in the Viñales Valley of western Cuba (Alvarez Conde, 1957). During later explorations of the Sierra de los Órganos in the first half of the XX Century, Carlos De la Torre y Huerta collected not only ammonites, but also numerous Jurassic fossil vertebrates, which were deposited in the Department of Geology and Paleontology of the University of Havana. In these early decades Carlos De la Torre y Huerta also lead Barnum Brown to collect Jurassic fossils for the American Museum of Natural History, and Brown and O'Connell (1922) reported, for the first time, the occurrence of fossils marine reptiles in Cuba. Some of these specimens were described (De la Torre y Madrazo and Cuervo, 1939; De la Torre y Madrazo and Rojas, 1949, De la Torre y Callejas, 1949), but many remained unidentified. Field collecting of reptile bones continued during the whole century by different individuals, generally guided by Juan Gallardo (an expert fossil hunter), and the specimens were treasured in the Museo Felipe Poey of the University of Havana, in some private collections, and at the National Museum of Natural History (Washington, D.C.), the American Museum of Natural History (New York) and the Museum of Paleontology at Berkeley (California). These materials were not studied, with the exception of a pterosaur from the collection of the American Museum of Natural History (Colbert, 1969). A more recent report of a fossil Jurassic reptile (Gutiérrez, 1981) unfortunately can not be evaluated because of the lack of illustrations, and because the material is lost. Furthermore, scarce and generally undescribed fossils of reptiles have been found in the Tithonian El Americano Member of the Guasasa Formation, and the Kimmeridgian- Tithonian Artemisa Formation (Pszczólkowski, 1978; Iturralde-Vinent and Norell, 1996). During the 1980 s and 1990 s, one of the authors (M.I.-V.) visited the Cuban fossil reptile collections in the museums of the United States (US National Museum of Natural History, American Museum of Natural History, and the Museum of Paleontology of the University of California in Berkeley); and every paleontologic collection in Cuba. Through collecting, exchange and donation, it was created the Jurassic reptile's collection of the Museo Nacional de Historia Natural de Cuba (MNHNCu). Simultaneously, the fossilbearing localities reported both in the literature and in the museum's specimen's tags 2

3 were revisited in order to establish their actual location. For this job Juan Gallardo and his senior son (natural born fossil hunting experts) were instrumental, as they knew all the fossil-bearing sites. A catalog of the Jurassic reptile-bearing localities with a preliminary discussion of the taxonomic position of the previously published taxa, was published (Iturralde-Vinent and Norell 1996). A new step in the investigations of the fossil Jurassic reptiles started in 1999, with field expeditions supported by the National Geographic Society, and the beginning of a very successful collaboration between the Museo de La Plata (Argentina) and the Museo Nacional de Historia Natural (Cuba). As part of this cooperation, every important specimen was prepared in Argentina. Previous miss-identifications could be characterized and emended, and new taxa were described (Fernández and Iturralde-Vinent 2000; de la Fuente and Iturralde-Vinent 2001; Gasparini and Iturralde-Vinent 2001; Gasparini, Bardet and Iturralde-Vinent, 2002, Gasparini, Fernández and de la Fuente, 2004). At the same time, the geology and taphonomy of the fossil-bearing rocks were investigated, and Jurassic paleogeographic maps, produced (Iturralde-Vinent, 2003, 2004). Fig. 1. General map of Jurassic fossil-bearing localities in western Cuba mentioned in this paper. See Table 1 for more information. Updated from Iturralde-Vinent and Norell (1996). Table 1. Additional details of the localities mentioned in this paper. Generally these paleontologic sites represent around one square kilometer, and their limits are undefined. 3

4 The collecting terrains are in the slopes, creeks and farmlands near the karstified limestone hills (locally named mogotes). Coordinates are of a middle point in the collecting area, referred to the Cuban 1: scale topographic map. Locality Topographic sheet Coord. X Coord. Y Cerca de Viñales (a) Consolación del Sur and La - - Palma Puerta de Ancón Consolación del Sur Laguna de Piedra Consolación del Sur Hoyos de San Antonio La Palma Jagua Vieja La Palma Hacienda El Americano La Palma (b) Hoyo del Palmar La Palma Caiguanabo Herradura Hoyo de la Sierra Herradura Notes: (a) This is an ambiguous locality reported in specimens collected early in the XX Century. It can be any place between Puerta del Ancón, Laguna de Piedra and Hoyos de San Antonio. (b) The paleontologic sites in this table belong to the Jagua Vieja Member of the Jagua Formation, with the exception of the Hacienda El Americano, which belong to the Tithonian-Berriasian El Americano Member of the Guasasa Formation (Pszczolkowski, 1978; Iturralde-Vinent and Norell 1996). The fossil record of Oxfordian marine reptiles is poor worldwide (Persson, 1963; Bardet, 1995) and generally, findings are reported from the Northern Hemisphere. These are for example the reptiles from the Oxford Clay (Callovian- Lower Oxfordian) of England, equivalent deposits of France (Martill and Hudson, 1991; Bardet, 1993, 1995; McGowan and Motani, 2003), those found in Russia and neighbor countries (Storrs et al., 2000), and the Sundance Formation and equivalents (Upper Oxfordian) herpetofauna in Wyoming, Montana and Alaska (Bakker, 1993b; Massare and Sperber, 1999; O Keefe, 2003a, 2003b). In western Cuba, the mid-to-late Oxfordian marine herpetofauna is particularly important, not only for its taxonomic diversity, but also because the time span of the faunule, poorly represented in other latitudes (see O Keefe, 2001a, 2003a, 2003b). Considering only the specimens identified up to family level, they indicate that this marine fauna is dominated by plesiosauroids (17/32), but other groups such as ichthyosaurians (4/32), metriorhynchids (4/32), pliosauroids (2/32), and turtles (1/32) 4

5 are present; while the terrestrial herps are represented by pterosaurs (3/32) and dinosaurs (1/32). In this paper we summarize our investigations of the Cuban Late Jurassic herpetofauna, and propose a paleoenvironmental scenario, analyzing the role of the Caribbean Seaway in the distribution of pelagic predators. In order to abridge the systematic information, an annotated list of the Oxfordian Cuban herpetofauna is included as Appendix 1, complemented with Tables 2-3. Cuban paleontological sites reported in this paper are located in Fig. 1 and Table Geological setting The Jurassic fossil-bearing rocks in western Cuba crop out in the Sierra de los Órganos and Sierra del Rosario of the Guaniguanico mountain range, as part of the?lower Jurassic through Middle Eocene sedimentary rock sections (Fig. 1, Table 1). These rock sections encompass the evolution of Pangea (?Lower-Middle Jurassic to early Oxfordian siliciclastics with rare limestone and mafic igneous intercalations) into the Laurasian passive margin- early Caribbean sea (mid Oxfordian through Late Cretaceous shales, sandstones, basalts, limestones and cherts), as well as into a foreland basin (Paleocene through Middle Eocene limestones, shales, breccias and olistostromes with olistoplates). These rock suites are amalgamated within an allochthonous terrane named Guaniguanico (Iturralde-Vinent, 1994, 1998), which originated as part of the Maya (Yucatán) block borderland (Iturralde-Vinent, 1994); probably close to the latitude of Belize and to the north (Hutson et al., 1999). The whole unit is strongly deformed, locally with some degree of metamorphism, and piled up as a stack of allochthonous tectonic sheets verging north and northwest. The degree of deformation varies, but important for the preservation of the fossils is the fact that the siliciclastic members of the sections, as the fossil-bearing Jagua Formation, are usually much more folded and faulted than the limestone members (Piotrowska, 1978; Pszczólkowski, 1978). This fact facilitates weathering and may have broken or dismember some bones preserved in the shales. The Jurassic stratigraphy of Guaniguanico has been described in detail by Pszczólkowski (1978, 1999), as well as the Oxfordian strata (Wierzbowski, 1976). Herein we focus on the description of the lithology and taphonomy of the fossil-bearing Jagua Vieja Member of the Jagua Formation Jagua Vieja Member A unique fossil-producing unit in western Cuba is represented by the mid to early Late Oxfordian Jagua Vieja Member of the Jagua Formation (Fig. 2). This unit is up to 60 meters thick black to gray colored bituminous shales and calcareous shales, laminated or thin bedded, with intercalations of thin bedded limestone beds. Within the shale matrix 5

6 occur fossil-bearing calcareous concretions at almost every level. In many localities, at the base of the Jagua Vieja Member occur an oyster-rich horizon, few centimeters thick, which overlies the deltaic-marine shales and sandstones of the San Cayetano Formation. In other localities, below the Jagua Vieja Member are found the Pan de Azúcar and Zacarias Members, represented by well-bedded shales, some fine grain sandstones, as well as shelly and bioclastic limestone with oyster-rich coquinal horizons (Wierzbowski, 1976; Pszczólkowski, 1978). This oyster-rich level represents the facies transition between the marine-deltaic San Cayetano and the shallow marine Jagua Vieja Member, generally middle Oxfordian in age. Table 2. Jurassic reptiles identified from the Jagua Formation. TAXON REFERENCE Pleurodira: Caribemys oxfordiensis de la Fuente and Iturralde-Vinent, 2001 Metriorhynchidae indet. Gasparini and Iturralde-Vinent, 2001 Metriorhynchidae: Geosaurus sp. Gasparini and Iturralde-Vinent, 2001 Cryptoclididae: Vinialesaurus caroli Gasparini, Bardet and Iturralde-Vinent, 2002 Thalattosuchian This paper Pliosauridae: Peloneustes sp. Gasparini (in study). Ichthyosauria: Ophthalmosauria Fernández and Iturralde-Vinent, 2000 Rhamphorhynchidae: Nesodactylus hesperius Colbert, 1969 Rhamphorhynchidae: Cacibupteryx caribensis Gasparini, Fernández and de la Fuente, 2004 Dinosauria: Camarasauromorpha Leonardo Salgado (personal communication) sensu photo in De la Torre y Callejas, 1949 Fig. 2. Combined lithostratigraphic sections of the Jagua Vieja Member of the Jagua Formation, according to new field observations by the authors. See Wierbowski (1976) for more details. 6

7 Concretions are lenticular and very variable in size, from a few centimeters up to nearly one meter across, and are composed of micritic limestone or dolostone with or without lamination. Most of them are fossiliferous. Concretions are found in situ, within the dark shales, as well as loose in the soil, at the base of the slopes where the Jagua Vieja Member outcrops, and in trails around the tobacco plantations piled up along by the farmers. Fossils found in these concretions include vertebrates, invertebrates, as well as plant remains. The internal lamination of the concretions, when present, is planar and intersects the fossil elements, in opposition to sedimentary lamination that usually retains the shape of the fossil element. Outcrops are sparse, and the shales are usually weathered to reddish soil Depositional environment The base of the Jagua Vieja Member seems to be deposited at very shallow depths, up to a dozen meters, in aerobic conditions, as suggested by the oyster lumachelles with onkolites and algal crusts (Wierbowski, 1976). According to Wierbowski (1976), those parts dominated by bituminous shales, represent generally anoxic conditions, where benthic fauna was rather monotonous and impoverished, without benthic foraminifera or burrowers, being represented mostly by pelecypods (primarily oysters), overgrowing shells of dead ammonites. On the other hand, those parts of the sections with abundant calcareous concretions, yielded microfossils characteristics of low energy, shallow water, near shore, generally protected areas (Table 4). The presence of benthic foraminifera, ostracods, pelecypods, gastropods and brachiopods in these levels, also suggests that the sea bottom was generally aerobic to slightly disaerobic. According to Wierbowski (1976) the marked predominance of Perisphinctidae ammonites in the Jagua Vieja Member seems to indicate sedimentation at shallow depths, but up to one or two hundred meters. The common occurrence of pycnodontiform fishes (Gyrodus sp. and others) also suggests shallow marine environment in the upper slope of the shelf (Kriwet, 2001a). Pycnodont fishes are bottom dwellers, which feed mainly on invertebrates (Kriwet, 2001b). Indicators of the paleoenvironment are the marine reptiles which include both coastal and open marine dwellers (Fig. 3). The presence of at least two Pterosauria genera (Nesodactylus and Cacibupteryx), the coastal dweller pleurodiran turtle Caribemys, and dinosaur remains also suggests that the coastline was not very far 7

8 from the depositional center. The analysis of the wackestones-packstone where the turtle Caribemys was included yielded detrital vegetal remains and microfossils as Favreina salevensis (Parejas), Favreina sp., Globochaete alpina Lombard, and ostracods with smooth hyaline shells. These organisms suggest that the sedimentary environment was a shallow water protected platform (de la Fuente and Iturralde- Vinent, 2001). The abundance of fish, some of them very large (up to ~1 m diameter), suggests enough food for long-necked plesiosaurs that dominated the reptile record, for the small, agile metriorhynchid crocodiles (Geosaurus sp.) and the ophthalmosaurian ichthyosaurs. A middle-sized pliosaur (Peloneustes sp.) played the top predator role. Characteristic of the basin was the absence of terrigenous input (no sandstone intercalations), suggesting that the surrounding lands were already invaded by the sea, and the surface topography was reduced to a low energy landscape. Under these conditions, the accumulation in the sediments of plant debris including large trunk and branch fragments (eventually bored by pelecypods) requires some mechanism carrying the fragments of terrestrial vegetation into the basin, as well as mud particles. Fine plant debris may have been carried into the sea by rain water, but larger elements probably were incorporated into the sediments during coastal inundation, as can be seen today in the southern littoral wetland areas of Cuba, where sea level is rising and mangroves are inundated and collapsing into the sea (M. I.-V. unpublished observations). Previous discussion suggests that the general Oxfordian scenario represented in by the Jagua Vieja Member of the Jagua Formation was one of a shallow marine continental margin (Laurasian) facing a deeper marine basin (Early ProtoCaribbean) (Iturralde-Vinent, 2003, 2004). The coastal areas probably were mostly wetlands. The presence of a herbivorous dinosaur (camarasaurian) and of abundant trunks would support this hypothesis. 3. Vertebrate taphonomy The fossil assemblage of the Jagua Vieja Member is dominated by marine elements, but plant remains are ubiquitous, and even very common as in Hoyo de la Sierra, where huge amounts of large elements occur. Some of the trunk fragments are isolated, without any portion of the concretions. This might suggest that they derived from the shales, as they show no signs of erosion. The vertebrate fossils are generally found in the concretions. They are very distinctive because bones are deep 8

9 black calcareous materials, while the color of the limestone matrix is usually lighter and the grain thinner. Skulls and postcranial bones are neither deformed nor compressed. Ammonite shells can be hollow and partially filled with calcareous sediment or sparry calcite, but some are hollow containing few loose biogenic(?) quartz crystals. The shells have lost the external nacre. Some fossils are preserved with great details, as most fish (Arratia and Schultze, 1985) and the pterosaurs (Colbert, 1969; Gasparini et al., 2004). Fish remains are often flattened, probably due to diagenetic desiccation, but three-dimensional specimens are not uncommon. They usually are not dismembered and retain the impressions of the fish scales, suggesting that the bodies were not altered by scavengers. The turtle Caribemys is incomplete, but it is unknown whether the missing parts are due to improper preparation or taphonomic causes. Reptile bones present a highly polished surface, they are generally recrystallized, and most skulls have lost the sutures. All these suggests an early diagenetic origin for the fossiliferous concretions (Pszczólkowski, 1978). The vertebrate fossils occur as complete or nearly complete carcasses, and as isolated fragmentary bones. Examples of articulated carcasses are mostly fish, and the partially dismembered carcass of a small pterosaur (Colbert, 1969). Only one carcass of a large marine reptile has been observed in limestones of the El Americano Member (Guasasa Formation), now lost due to quarry exploitation (G. Furrazola, personal communication, 1986). In many examples, fish carcasses and body impressions occupy the equatorial plane of the concretions, partially protruding within the periphery. If the body is large and elongated, one or both of the ends of the fish can be missing; but if the body is rounded, the whole periphery of the animal is usually missing. These examples clearly suggest that parts of the animals have been lost after fossilization. Also the elongated elements of fossil plants and reptiles intersect the outer surface of the concretions, no matter the orientation of the element within the concretion. This has been observed in examples of long bones, one or several articulated vertebrae, or a skull with some postcranial bones attached (Gasparini and Iturralde-Vinent, 2001; Gasparini et al. 2002). Skulls can be fairly complete or fragmentary, because of the partial lost of the cranial box or the tip of the nose; but many of them have the mandible articulated slightly twisted, i.e. the specimens of Vinialesaurus caroli, Peloneustes sp. and Geosaurus sp. (Fig. 5 A, B; C; E). This suggests that the missing part of those bones may have been preserved partially in the embedding shales, and later lost due to weathering or secondary erosion of the concretion. But decomposition and partial alteration of the carcasses 9

10 by microorganisms and bottom scavengers may have taken place, because some bones were exposed before burial. Evidence of the bone exposure prior to burial is the discovery of ammonites attached both to long bones (De la Torre y Callejas, 1949) and onto fragmentary skulls (Iturralde-Vinent and Norell, 1996). But no fossil bone is known to be recovered from the shales of the Jagua Vieja Member. The deformation of the shales, usually high, may have broken or dismembered some bones preserved in the shales. The degree of weathering of the shales is very high, because the limestone mountains (Sierra de Los Órganos) receive as much rain as 2000 mm a year, the relative humidity is high, and because surface waters not only drain to the rivers, but also percolate and infiltrate in great quantities, due to the strong fracturing and karstification of the limestones (Nuevo Atlas Nacional de Cuba, 1988). The high weathering level acts against the preservation of more complete carcasses. Probably large amounts of fossil material is currently dissolved within the shales, and also part of the exposed concretions are additionally eroded and further dissolved during transportation by surface drainage. These observations suggest that the Cuban fossil materials suffered a taphonomic history generally as described by Martill (1987). After death, the animals reached the sea bottom in flesh. In these conditions, parts of the bodies in contact with the sediment, and those partially buried in the mud, decayed at slow rate. Fish, for example, are fully preserved, even skin impressions, probably due to quicker burial. The same was probably true for the turtle Caribemys oxfordiensis de la Fuente and Iturralde-Vinent, In large animals as reptiles, burial rate probably did not covered the body so quickly, and parts of the flesh may have been temporarily exposed in the bottom water and decay, exposing some bones. Bone exposure is proved because ammonites have been found attached to some of them (De la Torre y Callejas, 1949; Iturralde-Vinent and Norell, 1996). The process described may cause the carcasses to collapse, and only some elements remain articulated and associated. With time, loosely associated carcasses, as the pterosaur Nesodactylus hesperius Colbert, 1969, may have been completely buried. There is no evidence of bones transported by bottom currents, besides carcass selfdismembering (Fig. 6 B). After burial, diagenesis produced the calcareous concretions that engulfed parts of the carcasses, while other parts were probably preserved within the shales. Therefore, we hypothesize that some large marine reptiles in the Jagua Vieja Member may be more fully preserved, even articulated carcasses, deep below the weathering horizon. This conclusion cannot be fully 10

11 extrapolated to the fossil remains of dinosaur found in the Jagua Vieja Member, a long bone which lacks both epiphyses and have an ammonite shell attached. As terrestrial animals, the dead bodies must have been subaerially deposited, and later carried into the marine environment for its final preservation (De la Torre y Callejas, 1949). Fig. 3. Jagua Vieja Oxfordian Vertebrates, represented as an hypothetical cross section from Laurasia (Dinosaurs and pterosaurs), trough the coastal areas (pterosaurs, chelonia, fish) and into the Caribbean Seaway (pliosaurs, plesiosaurs, crocodyliforms, fish) (not to scale). 4. General paleogeography during the Oxfordian During the Upper Jurassic the oceanic gap between North America and Gondwana widened due to the process that produced the disruption of Pangea (Fig. 4). This widening gap limited the possibility of direct overland dispersal between the land biotas of these continental areas. Probably since the Bajocian, but surely since the Oxfordian, such a possibility came to a close (Iturralde-Vinent and MacPhee, 1999). A true marine basin with ocean crust was developing within the Gulf of Mexico since the Callovian, and within the Caribbean since the Oxfordian. But the Gulf of Mexico was an independent marine tongue of the Pacific Ocean until the latest Jurassic (Kimmeridgian-Tithonian), when finally communication with the Caribbean 11

12 and the Atlantic was developed (Salvador, 1991; Marton and Buffler, 1999). Before the Kimmeridgian, an emerged ridge was present between present-day Florida and Yucatan, which separated the Gulf of Mexico from the Caribbean. This peninsular land ridge probably supported the terrestrial biota represented in the Jagua Formation. The Caribbean Seaway (a true corridor only since the Oxfordian) was widely opened to allow exchange of pelagic marine biota between Western Tethys and Eastern Pacific realms (Fig. 4; Iturralde-Vinent, 2004). By the end of the Jurassic this off-yucatan Laurasian continental margin (Guaniguanico terrane) developed into deeper marine environments (Pszczólkowski, 1978, 1999; Sánchez-Barreda, 1990; Schaffhauser, et al., 2004), and sparse remains of marine reptiles have been reported in these rocks (Tithonian-Berriasian El Americano Member of the Guasasa Formation). Fig. 4 Simplified Oxfordian paleogeographic map of the Caribbean with a small insert of the world scenario. Shaded is land. Two way arrows suggest possible marine migratory patterns. During the Oxfordian the Caribbean Seaway operated as a corridor for the marine biota. Modified from Iturralde-Vinent (2004). 12

13 Table 3. Jurassic herpetofauna from different localities of the Jagua Formation. With the exceptions of the pterosaurs and some marine crocodyliform fragments, these specimens are treasured in the paleontological collection of the National Museum of Natural History in La Habana. LOCALITY Caiguanabo Hoyo de la Sierra Hoyo del Palmar Hoyos de San Antonio Jagua Vieja Laguna de Piedra Puerta del Ancón Near Viñales (ambiguous location, generally within the eastern part of the Viñales valley) HERPETOFAUNA Pliosauridae (Peloneustes sp.) Thalattosuchian; Plesiosauroidea, Rhamphorhynchid pterosaur. Rhamphorhynchid pterosaur (Nesodactylus hesperius), Plesiosauroidea Rhamphorhynchid pterosaur, Ichthyosauria, Pliosauroidea. Rhamphorhynchid pterosaur (Cacibupteryx caribensis), Camarasauromorph dinosaur, Ichthyosauria. Plesiosauroidea, Metriorhynchidae. Metriorhynchidae. Pleurodiran turtle (Caribemys oxfordiensis), Plesiosauroidea (Vinialesaurus caroli), Metriorhynchidae (Geosaurus sp.), Ichthyosauria (Ophthalmosaurian). Table 4. Microfossils in calcareous concretions of the Jagua Vieja Member, identified by Silvia Blanco. Localities: 1, Mogote Guacamaya, near Jagua Vieja (dolostone); 2, Hoyo de La Sierra (wackestone-packstone); 3, Mogote Jagua Vieja (wackestone); 4, Sierra de Guasasa (wackestone-packstone). Localities in Figure 1 and Table 1. LOCALITIES MICROFOSSILS Glomospira? Sp * Colomisphaera cf. C. Fibrata * Favreina salevensis * Favreina sp. indet. * * Globochaete alpina * * Globochaete sp. Small gastropods and pelecypods * * Ostracods with smooth hialine * * shells Terrestrial plant remains * Hedbergella sp. * Cadosinidae * Crustocadosina aff. C. Semiradiata * Committosphaera sp. * Calcisphaeras (or Radiolaria?) * Benthonic foraminifera * 5. Paleobiogeographic comments A shallow marine connection, perhaps intermittent, between the Western Tethys and Eastern Pacific through central Pangea (so called the Hispanic Corridor by Smith, 1983), since the beginning of the Jurassic, has been proposed by numerous authors who recognized, in both geographic realms, the same genera and even 13

14 species of marine invertebrates (Damborenea and Manceñido, 1979; Hallam, 1983; Ballent and Whatley, 2000; Damborenea, 2000; Aberhan, 2001; Riccardi, 1991). Gasparini (1978, 1985, 1992, 1996), Gasparini and Fernández (1996, 1997) and Gasparini, Vignaud and Chong (2000) also proposed that at least since the early Bajocian, South America and Western Europe shared the same genera, or alike forms of marine reptiles, and thought that the most plausible way of geographic connection might have been the Caribbean Seaway. However, it is not until the Oxfordian when marine reptiles are first recorded in the Caribbean realm. The opening of this oceanic seaway represents an important paleoceanographic event, as only since that moment it may had started the Mesozoic deep circumequatorial oceanic circulation that linked the Tethys, Central Atlantic and Eastern Pacific oceans (Iturralde-Vinent 2003, 2004). Since Smith (1983) several author have named the Caribbean Seaway as "Hispanic Corridor", but here we challenge the liberal use of this term. Corridor means full communication and faunal exchange, which is only true for the Caribbean Seaway since the Oxfordian (Iturralde-Vinent, 2004). Previously, the Caribbean seaway was not well developed, and probably was represented by a system of intercontinental channels which probably were only temporarily connected during high sea level stands (Iturralde-Vinent, 2004). In these conditions, before the Oxfordian, and probably since the Pliensbachian, the Caribbean was more a filter than a corridor for the marine faunas (Damborenea, 2000). On the basis of the phylogenetic analysis of the teleosteans of the Oxfordian of northern Chile, Viñales (Cuba), and the Tithonian of Solnhofen (Germany), Arratia (1996) concluded that the fossil record supports a connection between European and Chilean fish fauna through the Caribbean seaway. Accordingly, Myczynski et al. (1998) recognized the same ammonite Zones in the middle-upper Oxfordian of Chile, southern USA, Cuba and Iberia. Unfortunately, the record of marine reptiles form the middle-upper Oxfordian is not frequent worldwide, consequently, biogeographic interpretations are not conclusive. However, marine reptiles from Cuba yield more information when analyzed within the groups linked to the Oxfordian-Tithonian. The main North American exposures with upper Oxfordian marine reptiles are those of the Redwater Member of the Sundance Formation and equivalent, in Wyoming and Montana. They are known since the beginning of the XXth Century, mainly through the ichthyosaur Ophthalmosaurus (=Baptanodon) (Gilmore, 1906, McGowan and Motani, 2003), but 14

15 only since the papers of Bakker (1993 a, b) and those more recent by O Keefe and Wahl (2003 a, b) on plesiosauroids, the richness of the marine reptiles composed also of Pliosaurus sp. and metriorhynchids (Bakker, 1993b) is confirmed. The middleupper Oxfordian rocks of western Cuba, bear a related herpetofauna, but with higher taxonomic diversity. Likewise, most of the Oxfordian reptiles of America and Cuba have close phylogenetic relationships with those of the Callovian-late Jurassic of Europe (Motani, 1999; Fernández, 2000; Gasparini and Iturralde-Vinent, 2001; Gasparini et al., 2002; O Keefe and Wahl, 2003a, b). Gasparini et al. (2003) indicated that the plesiosauroid Vinialesaurus from Cuba has strong affinities with Kimmerosaurus Brown from the Kimmeridgian and with Tricleidus Andrews from the Callovian, both of England (Brown, 1981). In turn, O Keefe and Wahl (2003b) also outlined the affinities of the plesiosauroid Tatenectes laramensis Knight, 1900 new comb., from the Sundance Formation with Kimmerosaurus and Tricleidus. The ichthyosaur Ophthalmosaurus is recorded in the Sundance Formation (McGowan and Motani, 2003), and also from the Callovian to Tithonian in Europe (Bardet et al., 1997), and in the Tithonian of northern Patagonia (Fernández, in press). In Cuba, the most complete ichthyosaur fragment was referred by Fernández and Iturralde-Vinent (2000) to an ophthalmosaurian, but they recognized traits as very large orbital cavity and sclerotic ring, as well as the extracondylar area of the basioccipital reduced, as in Ophthalmosaurus. Several remains of metriorhynchid crocodiles were found in western Cuba, at least one of them belongs to Geosaurus sp. (Gasparini and Iturralde-Vinent, 2001). This is the oldest record of the genus. Bakker (1993b) reported the presence of metriorhynchids in the Sundance Formation, but they have not been studied or illustrated so far. It is noteworthy that Geosaurus Fraas, has been recorded in the Tithonian of eastern Mexico (Stinmsbeck et al., 1993; Frey et al., 2002), the Tithonian of northern Patagonia (Gasparini and Dellapé, 1976) and the Tithonian of Germany (Bardet, 1995; Vignaud, 1995), a distribution that encompasses at least the European Tethys, the Caribbean Seaway and the Eastern Pacific. In the Middle-Upper Oxfordian of Cuba were also found a skull and mandible of Peloneustes sp. (ZG, in study). Peloneustes is a middle sized pliosaur frequent in the Callovian from the Oxford Clay (O Keefe, 2001a). Bakker (1993b) reported the presence of Pliosaurus sp. in the Sundance Formation, but no studies or illustrations of the material are offered. A revision of the top-predators of the Middle-Late Jurassic is needed, since frequently, fragmentary material, which does not reach the 15

16 gigantism of Liopleurodon Sauvage (O Keefe, 2001a), has been referred to Pliosaurus Owen. Caribemys oxfordiensis is the oldest marine Pleurodiran turtle known. De la Fuente and Iturralde-Vinent (2001) recognized its relationships to other pleurodirans from the Upper Jurassic, such as Platychelys from the Kimmeridgian and Tithonian of Europe and Notoemys Cattoi and Freiberg, 1961 from the Tithonian of northwestern Patagonia (Fernández and de la Fuente, 1994). The Rhamphorhynchidae (Unwin et al., 2000; Unwin, 2003) are represented in the fossil record from the Toarcian to the Tithonian, but the Oxfordian and Kimmeridgian forms are poorly known (Wellnhofer, 1991; Bennett, 1995). Therefore, the holotype of Cacibupterys caribensis is the best preserved middle-late Oxfordian pterosaur skull reported so far (Gasparini et al., 2004). The phylogenetic relationships of Cacibupteryx and Nesodactylus are not resolved. This, together with their flying capability of dispersion, make not feasible at present to produce a biogeographic scenario. Concerning the probable record of a camarasaurid in western Cuba, probably derived from the Florida-Yucatan ridge (Fig. 4), is coherent with their distribution in the Kimmeridgian-Tithonian of North America (McIntosh, 1990). 6. Conclusions Given the present state of our knowledge of the Oxfordian reptiles from Cuba, it may be concluded that: (1) Fossil remains of Jurassic reptiles known from western Cuba (Guaniguanico Terrane), have been collected mostly from the middle-upper Oxfordian Jagua Vieja Member of the Jagua Formation, cropping out in the Sierra de los Órganos (Pinar del Río province). (2) These fossil-bearing rocks were deposited in shallow marine conditions on the continental margin of Laurasia (with coastal wetland) facing the Caribbean deeper oceanic seaway. (3) The vertebrate fossils reported from Jagua Vieja Member have been historically recovered from calcareous concessions embedded in black shales, where small elements as fish, turtle and pterosaurs are almost complete, but generally very incomplete carcasses of large marine reptiles are preserved. These are well-preserved isolated bones, articulated skulls and mandible, or a row of several vertebrae. (4) The taphonomic analysis suggests that there was no active predation of carcasses prior to fossilization. It is hypothesized that the missing parts of the carcasses were dissolved by weathering processes, probably by acidic rain waters percolating into the ground. (5) The fossil reptiles of the Jagua Vieja Member include both marine and terrestrial taxa. Marine 16

17 ones are represented by Crocodyliformes (Geosaurus sp., and thalattosuchians indet.), Pliosauriomorphs (Peloneustes sp.), Plesiosauromorphs (Vinialesaurus caroli), Icthyosauria (Ophthalmosauria), Chelonii (Caribemys oxfordiensis). Of terrestrial origin are Pterosauria (Nesodactylus hesperius, Cacibupteryx caribensis) and camarasaurid dinosaurs. (6) The marines reptiles from the middle-upper Oxfordian of Cuba are closely related to middle-late Jurassic forms of the European Tethys and late Jurassic forms of the Eastern Pacific (Oxfordian Sundance Fm. of northwestern North America and Tithonian Vaca Muerta Fm. of northwestern Patagonia). (7) The Jurassic Caribbean Seaway was a corridor for the dispersion of pelagic reptiles between the European Tethys and the Eastern Pacific since the Oxfordian, as well as a barrier to dispersion of continental forms between Laurasia and Gondwana. The Jurassic deep marine dweller reptiles recorded in western Cuba had the morphofunctional capability to move thousands of kilometers, hence, seasonal displacements may not be discarded. Acknowledgements We are deeply grateful to Juan Gallardo and Juanito Gallardo Jr. (Museo de Viñales, Pinar del Río) for their invaluable support and expertise during many years of field work. Also to Reinaldo Rojas, William Suárez and Stephen Díaz (Museo Nacional de Historia Natural, La Habana) for their help during some field expeditions. Silvia Blanco and José Fernández (Centro Investigaciones y Desarrollo del Petróleo, La Habana, Cuba), kindly identified the microfossils here reported. Leonardo Salgado (Universidad del Comahue, Argentina) kindly identified the dinosaur specimen. Likewise we thank Javier Posik and Juan José Moly (Museo de La Plata) for the preparation of the specimens and Dr. Cecilia Deschamps for the edition of the manuscript. MI-V thanks the National Geographic Society for Grants and that partially financed the fieldwork and preparation of some samples, and US National Museum of Natural History (Washington), American Museum of Natural History (New York), Museum of Paleontology (Berkeley) that kindly allowed the study of Cuban fossils collections. Z.G. thanks the National Geographic Society for Grants and that partially financed the preparation and study of Cuban reptiles, and collection studies at the Natural History Museum (London) and Geologisch-Paläontologische Institut der Universität, Tübingen, Germany. Z.G. thanks Angela Milner and M. Maisch, respectively granted authorization to examine the collections of Jurassic marine reptiles of the mentioned institutions. 17

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