Pachysuchus is known from a poorly preserved partial rostrum that was described from the Lower Lufeng Series in Yunnan by paleontologist Yang Zhongjian ("C.C. Young") in 1951.[1] The type species is Pachysuchus imperfectus. The generic name translates as "thick crocodile"; the specific name means "imperfect" in Latin. Young identified the rostrum as that of a phytosaur, a long-snouted crocodile-like crurotarsan. Phytosaurs were common in the Triassic, but none are otherwise known from the Jurassic. They are thought to have gone extinct during the Triassic-Jurassic extinction event. The rostrum from which Young described the specimen had since been lost, and his first description of the genus had been questioned.[2] The poor preservation of the specimen and its presence in Jurassic beds makes it doubtful that Pachysuchus is a phytosaur.[3] Paul M. Barrett and Xu Xing (2012) relocated the holotype of P. imperfectus, specimen IVPP V 40, and identified it as actually belonging to a taxonomically indeterminate basal sauropodomorph. According to Barrett and Xu, the holotype of Pachysuchus "does not bear any unique features or a unique character combination"; it differs from rostra of other Early Jurassic Chinese sauropodomorphs, but it cannot be ruled out that the differences are caused by its poor preservation, making it a nomen dubium.[4]
