Nothosaurus sp (Reptilia, Sauropterygia, Nothosauridae) from the Anisian (Middle Triassic) of Guizhou, southwestern China

摘要

A complete nothosaurid skull, exposed in ventral view, is described from the Upper Member of the Guanling Formation (Pelsonian, Middle Anisian) of Xinmin, Panxian County, Guizhou Province, southwestern China. The combination of some characters of the skull and dentition, including a spatulate rostrum followed by a marked rostral constriction, four premaxillary fangs followed by a distinctly smaller premaxillary tooth, five smaller maxillary teeth rostral to the paired maxillary fangs, makes it different from other nominal species of Nothosaurus. As data on the dorsal surface of the skull are lacking, it is identified as Nothosaurus sp., although it probably represents a new species. It is the second representative of the genus Nothosaurus from southwestern China and outside the western Tethyan faunal province, and the oldest definite record of a nothosaurid sauropterygian in southwestern China as well as one of the oldest known nothosaurids worldwide.