On the Occurrence of Crocodylus (Reptilia, Crocodilidae) in the Cayman Islands, British West Indies

Abstract

A small crocodile tooth from a cave fossil deposit on Grand Cayman provides the first reliable record of a crocodilian from that island. Although the tooth is not diagnostic beyond the generic level, it is referable to Crocodylus. Previous accounts of crocodile sightings in the Cayman Islands from both the herpetological and historical literature are reviewed and their reliability commented upon. The present recrod, in addition to a comparatively modern specimen of C. acutus from Little Cayman, confirms the former presence of crocodiles in the Cayman Islands. The lack of sightings or specimens of Crocodylus from the Caymans in the past 40 years provides strong evidence that crocodiles no longer occur in that island group. * * * During the processing of fossil vertebrate material collected from a small cave on Grand Cayman, B.W.I. in the spring of 1976, the single tooth (UF 22739) of a small crocodile was recovered. Because the presence of Crocodylus on the Cayman Islands has long been a subject of confusion and dispute, we regard this discovery as significant in that it is the most reliable record of the former occurrence of a crocodile from Grand Cayman and only the second verifiable record of a crocodilian from the Cayman Island group. The cave, herein named Crab Cave, is located in the town of East End (designated as Old Isaacs on the 1966 topographic map of Grand Cayman, Directorate of Overseas Surveys map series 328, Tolworth, Surrey, England) in the extreme southeast corner of Grand Cayman (coordinates: 19? 18' N, 81? 06' W). More precise information on this cave can be found in Morgan (1977). The cave opens at the base of a 7 m bluff that probably was cut during a late Pleistocene high sea level stand. Approximately 200 m in from the shoreline, the base of this low bluff is just a meter or so above present sea level. The fossil crocodile tooth was dug from a cave floor deposit and was found in association with various terrestrial vertebrates, including rodents, bats, snakes, and the abundant remains of the rock iguana, Cyclura nubila. Marine invertebrate fossils, particu- larly gastropods, were also found mixed with the terrestrial forms, the association probably resulting from the activities of the ubiquitous hermit crabs rather than from intermittent marine deposition during higher sea levels. Nothing in either the lithology of the cave sediments of their stratigraphic relationships indicates that the cave was submerged during their deposition. On the wave-cut terrace between the bluff and the sea lies a dwindling, elongate saltwater swamp that on geomorphic grounds appears to date back at least to the late Pleistocene. Except for the activity of man, which has mostly destroyed it, the swamp would even today provide adequate crocodile habitat. This is the only saltwater swamp on the southeast coast of Grand Cayman. Unfortunately, because of individual and age variation in the teeth of crocodiles, the Grand Cayman specimen cannot be identified beyond recognizing it as belonging to the genus Cro- codylus. Varona (1966) has described a fossil crocodile, C. antillensis, from a cave west of Havana, Cuba. Lack of comparable elements prevents a comparison of the Grand Cayman tooth with this species. Crocodylus acutus is found in the West Indies on Cuba, the Isle of Pines, several small