WAS THE P-T RECOVERY DELAYED ON LAND? A COMPARISON WITH THE K-PG RECORD

The uniqueness of the restructuring interval that followed the end-Permian extinction event can only be evaluated if P-T research can be placed into the larger context provided by analyzing other post-extinction intervals. This study places the restructuring of terrestrial tetrapod communities following the P-T extinction into such a context by comparing it to the interval that followed the K-Pg extinction event. We compared the pace and structure of community-level generic richness change for the first 10 Ma following each extinction. Data from three study areas was used in this analysis; the Karoo Basin in South Africa and Cis-Urals in Russia for the Early to Middle Triassic, and the northern Great Plains in the U.S. for the Paleogene. An extended survival interval is observed in the Early Triassic in both South Africa and Russia, during which time generic diversity is low and stagnant. No survival interval is found during the Paleogene, and instead increasing generic diversity is seen immediately after the extinction. The total duration of the restructuring interval appears to have been as much as 3 Ma longer during the Triassic than during the Paleogene. These findings suggest that substantive differences in either biotic dynamics or abiotic conditions existed between these two post-extinction intervals.