A new species of Lariosaurus (Reptilia, Sauropterygia) from the Middle Anisian (Middle Triassic) of southwestern China

An almost complete nothosaurid skeleton is described from the Upper Member of the Guanling Formation (Pelsonian, Middle Anisian, Middle Triassic) of the Xinmin District, Panxian County, Guizhou Province, southwestern China. It represents a new species of the genus Lariosaurus, L. hongguoensis sp. nov. Its general morphology is in good agreement with other known species of Lariosaurus, but it differs from all other members of the genus by a unique combination of cranial and postcranial characters. These include seven premaxillary teeth, a relatively small temporal fenestra, the retention of the jugal and unfused nasals, a parietal skull table that is not constricted behind the parietal foramen, a large foramen chordae tympani, an almost reduced ectepiconylar groove, and hyper-phalangy in both manus and pes, among other features. It is the oldest definite representative of Lariosaurus known so far, and the second known lariosaur species outside of the western Tethyan faunal province.