The lizard genera Bainguis and Parmeosaurus from the Upper Cretaceous of China and Mongolia

Abstract

The lizard genus Bainguis was originally described from the Upper Cretaceous of Mongolia and attributed to Anguimorpha. The same genus was later reported from the Upper Cretaceous of Bayan Mandahu, Nei Mongol, China on the basis of a partial skeleton showing some similarities in osteoderm morphology. Re-examination of this specimen with the aid of μCT scanning suggests that it is, in fact, attributable to Parmeosaurus, a scincoid lizard described from the Ukhaa Tolgod locality, Mongolia, as do two new specimens from Bayan Mandahu. Moreover, some of the Mongolian material originally attributed to Bainguis appears also to belong to Parmeosaurus. And our new phylogenetic analysis confirms that Parmeosaurus is positioned on the stem of Scincoidea. Taken together, these specimens add new data to our understanding of Parmeosaurus but also raise questions as to the affinities of Bainguis.