TERRESTRIAL TETRAPOD VERTEBRATE PALEOEOCOLOGY ACROSS THE PERMIAN-TRIASSIC BOUNDARY AND ITS RELATIONSHIP TO THE GLOBAL CARBON CYCLE

Recent high-resolution studies of marine records of the end-Permian mass extinction boundary demonstrate that marine faunas suffered an abrupt extinction, and that these ecosystems did not fully recover until the early Anisian, some 5-7 million years later. Associated isotopic data indicate that the end-Permian extinction coincides with the onset of major perturbations to the global carbon cycle, which did not stabilize until the Anisian. This suggests that recovery from the end-Permian extinction was delayed in part by a variable environment susceptible to destabilization. In contrast, little is known about the end-Permian extinction and Triassic recovery in continental environments. Some previous studies of terrestrial vertebrate diversity suggest the end-Permian extinction was a minor event on land whereas others indicate a major turnover event and a protracted recovery. To understand the effects of the end-Permian extinction on land, we investigated changes through time in several paleoecological metrics for a dataset of Late Permian through Middle Triassic tetrapod vertebrate specimens from southern Africa. Raw and sample-standardized (rarefied) data indicate that taxonomic richness decreased dramatically across the Permian-Triassic boundary, and had not recovered by the beginning of the Anisian. Evenness also decreases across the boundary but recovers by the Anisian. Clade-specific patterns indicate that the taxonomic richness of several synapsid groups and parareptiles decrease significantly across the boundary, whereas that of temnospondyls and archosauromorphs increased. Relative abundance did not change significantly across the Permo-Triassic boundary, but altered greatly in the wake of the mass extinction. These data suggest that terrestrial ecosystems were severely affected by the end-Permian mass extinction, and that their protracted recovery was also impacted by changing environmental conditions as reflected in the global carbon cycle.