Taxonomic and ecomorphological diversity of temnospondyl amphibians across the Permian-Triassic boundary in the Karoo Basin (South Africa).

Temnospondyl amphibians experienced a geologically brief interval of success in the wake of the end-Permian mass extinction. This study examines the relationship between taxonomic and ecological diversity of temnospondyls across the Permian-Triassic boundary in the Karoo Basin of South Africa. Ecomorphological diversity, as implied by differences in cranial shape, was incorporated into the study by the use of a landmark-based geometric morphometric analysis. Both taxonomic diversity and cranial disparity are low during the Permian and increase across the Permian-Triassic boundary. Taxonomic diversity is stable through the Triassic, but disparity shows subsequent increases during the Olenekian and Anisian. Temnospondyls are restricted in size immediately following the extinction, but size range fully rebounds by the Olenekian. Cranial shape is heavily influenced by phylogenetic relatedness, and the observed increases in disparity may be partly the result of decreases in the net relatedness of coeval Karoo stereospondylomorph temnospondyls in younger faunas. The increase in community level taxonomic diversity for temnospondyls in the Karoo following the end-Permian mass extinction was likely facilitated by an influx of distantly related and ecologically distinct species.