Phylogenetic relationships of Palaeogene ziphodont eusuchians and the status of Pristichampsus Gervais, 1853

Abstract

Eusuchians with deep snouts and labiolingually compressed teeth are known from the Palaeogene of Laurasia. These are usually referred to Pristichampsinae, but the type species, Pristichampsus rollinati, is based on insufficiently diagnostic material and should be treated as a nomen dubium. At least two Lutetian species formerly referred to Pristichampsus can be recognised - Boverisuchus magnifrons in Germany and possibly elsewhere in Europe, and Boverisuchus vorax, new combination, in western North America. Material from the middle Eocene of Italy and Texas may represent distinct species. A phylogenetic analysis confirms their close relationship and also supports a relationship with two Asian forms - early Eocene Planocrania datangensis and Palaeocene Planocrania hengdongensis. The name Planocraniidae Li 1976 is applied to this group. A distinctive quadrate with a prominent dorsal peak between medial and lateral hemicondyles is known only in Boverisuchus, and although the teeth of Planocrania are flattened, they are not serrated. Planocraniids maintain a phylogenetic position as the sister group to Crocodyloidea+Alligatoroidea, but this part of the tree is unstable and discovery of older, more primitive planocraniids will help resolve conflicts on the phylogenetic relationships of extant crocodylian lineages. © 2013 The Royal Society of Edinburgh.