The timing and nature of marine ecosystem recovery following the Permian-Triassic mass extinction

The Permian-Triassic mass extinction (PTME; c. 252 million years ago) was the most devastating extinction event of the Phanerozoic, resulting in up to 90% of marine animal species becoming extinct and profound ecological changes from Palaeozoic to Mesozoic faunas. The eruption of the Siberian Traps Large Igneous Province caused a cascade of environmental effects such as extreme warming, ocean anoxia and acidification which collapsed Permian ecosystems and delayed recovery in the Early Triassic. However, uncertainty remains regarding the temporal dynamics and nature of ecological recovery following the PTME. Models attribute a slow stepwise recovery within marine communities, from primary producers to top predators, reattaining pre-extinction levels of ecological complexity by the Middle Triassic. However, global empirical data indicates the rapid recovery of multiple trophic levels albeit in the form of top-heavy, unstable Early Triassic ecosystems. Further research promises exciting opportunities to apply community ecology models to ever improving databases of fossil ecosystems spanning multiple palaeolatitudes to test fundamental questions regarding the nature and timing of recovery and whether it really was “recovery” back to pre-extinction states; or “restructuring” to new baselines of ecosystem complexity more reflective of modern marine ecosystems.