The recovery of terrestrial vertebrate diversity in the South African Karoo Basin after the end-Permian extinction

Abstract

The southern half of the main Karoo Basin in South Africa contains an almost continuous stratigraphic record of terrestrial sedimentation through the Permo-Triassic boundary (PTB). Detailed logging of multiple sections through the boundary sequence has defined the end-Permian mass extinction event using vertebrate fossils as well as a synchronous change in fluvial style reflecting a rapid aridification of climate. Field data demonstrates a 69% mass extinction of Late Permian terrestrial vertebrates lasting some 300 kyr terminating at the PTB, followed by a lesser extinction event (31%) approximately 160 kyr later involving four survivor taxa that crossed the PTB. The Early Triassic recovery fauna comprises proterosuchian archosauromorphs ( Proterosuchus), small amphibians ( Micropholis, Lydekkerina), small procolophonoids ( ‘Owenetta’ kitchingorum, Procolophon), medium-sized dicynodonts ( Lystrosaurus) and small insectivorous cynodonts ( Progalesaurus, Galesaurus, Thrinaxodon). Taphonomic bias towards preferential preservation of drought accumulations in the Early Triassic has probably over-emphasized the abundance and diversity of semi aquatic and burrowing animals. To cite this article: R. Smith, J. Botha, C. R. Palevol 4 (2005) .