First thoughts on the aftermath of the end-Guadalupian extinction in tetrapods and the fate of the Pristerognathus AZ

DAY, M; RUBIDGE, B.S.; ABDALA, F.

Johannesburgo

Conferencia; 18th Biennial Conference of the Palaeontological Society of Southern Africad; 2014

Palaeontological Society of southern Africa

The Pristerognathus Assemblage Zone (AZ) of the Beaufort Group is one of the least studied biozones in the Karoo sequence. This zone is described as consisting of an impoverished remnant of the underlying Tapinocephalus AZ, characterized by low diversity and the prolific occurrence of a very few genera. The Pristerognathus AZ does, however, record the aftermath of an extinction that witnessed the disappearance of dinocephalian therapsids and of a large proportion of genera. The age of this biozone falls within the latest Middle Permian (Capitanian epoch of the Guadalupian stage) and may be linked to diversity crises recorded in the marine realm of China. In view of its position within a continuously exposed depositional sequence, the Pristerognathus AZ is therefore of particular significance in exploring the aftermath of the dinocephalian extinction. Stratigraphic fossil collecting in and immediately adjacent to thePoortjieMemberof theTeekloof Formation in the southwestern Karoo basin is providing high resolution data on the occurrence of fossil vertebrate taxa in the Pristerognathus Assemblage Zone. Together with fossil data from existing collections and the Beaufort FossilVertebrate Database, this is revealing that the Pristerognathus AZ may be more complex than currently understood and may potentially be subdivided. Perhaps more importantly, the first signs of recovery in the wake of the dinocephalian extinction are evident within the Pristerognathus AZ.