Ecosystem recovery following the Permo-Triassic mass extinction

Ecosystem recovery following the Permo-Triassic mass extinction. Lecture given by Annabel Nichols, University of Leeds School of Earth and Environment.

The Permo-Triassic mass extinction (PTME ~252Ma) was the most catastrophic biotic event of the Phanerozoic and recovery was protracted due to environmental instability through the Early Triassic. Although the PTME itself is well studied, there is debate surrounding the nature and timing of marine ecosystem recovery in the aftermath of the extinction. It is argued whether ecological recovery occurred in a step-wise bottom-up manner, with full recovery occurring contemporaneously with recovery of taxonomic diversity by the Anisian stage of the Middle Triassic (some 5-8 million years after the PTME), or whether Early Triassic communities recovered rapidly albeit with markedly different structure to pre-extinction ecosystems. We used lagerstätten data to track ecological recovery via snapshots of marine communities through the Triassic by modelling community structure and function. We show that marine communities recovered quickly in the aftermath of the PTME, but Middle Triassic communities show a significant increase in diversity and vertical structure compared to Early Triassic communities. This suggests that alpha diversity as well as marine community structure and function recovered fully by the Middle Triassic, in line with global taxonomic diversity, but this recovery did not occur via a step-by-step rebuilding of marine ecosystems through the Early Triassic.