A Redescription and Phylogenetic Analysis of the Cretaceous Fossil Lizard Polyglyphanodon sternbergi Gilmore, 1940

A detailed osteological description of Polyglyphanodon sternbergi (Polyglyphanodontia: Squamata), the most complete polyglyphanodontian lizard known from North America, is presented for the first time since Charles Gilmore first described this species in 1942. The material used for this description is currently housed at the Smithsonian National Museum of Natural History and consists of a large collection of well preserved, partially articulated skeletons and isolated elements representing nearly the entire skeleton. P. sternbergi's taxonomy and systematics is reviewed, and its inclusion in a recent comprehensive morphological phylogenetic analysis is revised and reanalyzed. The results of this analysis support the placement of Polyglyphanodontia as a scleroglossan stem clade, and reveal six new unambiguous synapomorphies of Polyglyphanodontia and seven new autapomorphies for P. sternbergi. Unique morphological traits of P. sternbergi are discussed, including the convergence of certain features such as its dentition with modern teiids and the paleoecological significance of these features.