A new taxon of helodermatid-like lizard from the Albian–Cenomanian of Utah

ABSTRACT

A new platynotan lizard, Primaderma nessovi, gen. et sp. nov., from the Mussentuchit Local Fauna, Cedar Mountain Formation (Albian–Cenomanian) of Utah is unique in having a premaxillary process of the maxilla that forms a vertical flange and fine serrations on anterior and posterior edges of the maxillary teeth. Primaderma is the oldest-known terrestrial platynotan and phylogenetic analysis indicates that it is a member of Monstersauria, a clade of helodermatid-like platynotans. The teeth of Primaderma show several derived platynotan characteristics, but do not possess venom grooves. The distribution of this trait in fossil taxa is reassessed. Although a North American origin of helodermatid-like platynotans is likely, it is possible that Primaderma represents another example of an Asian influence on the North American Cretaceous fauna. As with similar taxa, Primaderma was likely highly predaceous, presumably taking vertebrate prey and it appears that helodermatid-like lizards have changed very little since the Albian–Cenomanian.