A new crocodylomorph of “mesosuchian” grade from the Upper Cretaceous upper Milk River Formation, southern Alberta

ABSTRACT

A new Late Cretaceous neosuchian crocodylomorph, Gilchristosuchus palatinus gen. et sp. nov., is described on the basis of a partial skull from the basal Campanian or uppermost Santonian Milk River Formation of southern Alberta. This species is diagnosed primarily by the posterior extension of the palatine well beyond the suborbital fenestra, leading to a posterior shift of the choana. The primitive entrance of the palatines into the choana excludes G. palatinus from the Eusuchia. The posteriorly positioned choana and the presence of the postorbital/parietal contact, however, indicate that the species is the most derived non-eusuchian crocodylomorph.