江苏晚新生代的几种鳄类化石

LATE CENOZOIC CROCODILIA FOSSILS FROM JIANGSU

本文记述了发现于江苏西部晚新生代的鳄类化石,由于材料有限,种不能确定。它们是:Tomistoma sp., Diplocynodon sp., Alligator of. sinensis.

Some crocodilian fossils collected by the authors in recent years from late Cenozoic sediments of Jiangsu Province are described in the present notes. The materials are very fragmental, but at least three species and a problematic one are recognized in our collection, those being Tomistoma sp., Diplocynodon sp., Alligator of. sinensis and Crocodilidae gen indet. It is, however, of interest because some of them are known to occur for the first time in China. They are briefly noted in the following:Tomistoma sp.: The presence of a large-sized and long-snouted crocodile is indicated in our collection by a fragment of the left maxillary with six alveolus and an isolated tooth. The maxillary is very large and long, its inside suture shows that it is joined with the nasal and the premaxillary, this is the characteristic of Tomistoma. The size of the isolated tooth coincides entirely with the alveolus of the maxillary described above. Owing to few and broken materials, the species is undeterminable.Diplocyodon sp.: A dorsal scute suggests the presence of this genus. Its size and externally sculptured pit are very similar to that of Diplocynodon from Europe. Four isolated teeth referred to same genus are small and sharply conical, and comparable in size and morphological character to that of Diplocynodon geruaisi from Ronzon of France. It is also probable that these teeth represent other genus.Alligator of. sinensis: This species is represented in our collection by a well preserved dorsal scute. Its size and externally netted sculpture resemble that of the living A. sinensis in the same area. This dorsal scute is found from cave deposit and coexisted with Ursus actors, Pseudaxis, Cervocerus and Felids. The geological age of this vertebrate assemblage is probably Middle Pleistocene. This is the earliest fossil record of A. sinensis.Crocodilidae gen. indet.: A fragment of the dorsal scute and three isolated teeth. The dorsal scute is very thick (6.3mm), the surface sculpture differs from Alligator sinensis and Diplocynodon mentioned above. Three teeth ar larger than that of Alligator sinensis, but smaller than that of Tomistoma described above. Because the materials are few, generic and specific determination are impossible.