New information on Wumengosaurus delicatomandibularis Jiang et al., 2008 (Diapsida: Sauropterygia), with a revision of the osteology and phylogeny of the taxon

Wumengosaurus delicatomandibularis Jiang et al., 2008, is restudied on the basis of three new specimens. Many elements of the skeleton that were either briefly or not described at all in the original study are detailed. With the additional information derived from the new specimens, we have revised the diagnosis of W. delicatomandibularis. A phylogenetic analysis further demonstrates that the Pachypleurosauria is not a monophyletic group and questions that W. delicatomandibularis is closely related to the Pachypleurosauria. W. delicatomandibularis might represent the basal-most member of a monophyletic clade that includes the Nothosauroidea and those taxa assigned to the 'Pachypleurosauria.' The five known specimens show morphological variation in W. delicatomandibularis, as in Keichousaurus and in pachypleurosaurs such as Neusticosaurus and Serpianosaurus.