A new short-snouted rhinesuchid from the permian of southern Brazil

Abstract

A new basal stereospondyl taxon from the Permian is described. The material used to erect the new taxon consists of a series of mandibles and some postcranial elements. A single badly preserved short-snouted skull is considered as referred material. Rastosuchus hammeri gen. et sp. nov. presents conical teeth along all coronoid bones, the prearticular extending anteriorly at the level of the precoronoid and enlarged anterior meckelian foramina. Based on the referred material, R. hammeri gen. et sp. nov. also presents posterior premaxillary teeth larger than anterior ones, the cultriform process of the parasphenoid compressed laterally forming a medial ventral keel, posterolateral ramus of the vomer extends posterior to the palatine tusks, and rounded orbit with flat orbital bones at the same level of the skull roof, features shared with Australerpeton cosgriffi and other rhinesuchids. Australerpeton cosgriffi and Rastosuchus hammeri gen. et sp. nov. are from the upper layers of the Rio do Rasto Formation (Paraná Basin) in the Paraná State, southern Brazil, and its deposition in freshwater continental environments is reinforced by the presence of temnospodyls amphibians.