Extinction: End‐Permian Mass Extinction

Abstract The end‐Permian mass extinction (251.9 million years ago) was an abrupt and severe loss of diversity on land and in the oceans, the largest extinction of the Phanerozoic. Recent palaeontological, geochemical and modelling studies link the extinction with eruption of the Siberian Traps flood basalts, which would have caused ocean warming and acidification, and shallow‐marine anoxia. On land, global warming, punctuated with episodic cooling from eruption‐related sulfur aerosols, and aridification were mostly responsible for the vertebrate and plant extinction. Although almost no marine group emerged unscathed, selectivity favoured more active animals, while sessile and heavily calcified taxa such as corals and reef‐building sponges suffered heavily. The recovery interval was unusually long, likely because of continuing stress, and the extinction resulted in permanent shifts in marine ecosystem composition and structure, giving rise to the mollusc‐rich communities that still dominate today. The end‐Permian mass extinction was a severe crisis for nearly every plant and animal group, on land and in the oceans. The extinction was abrupt, apparently synchronous on land and in the sea in the tropics (but perhaps earlier among high‐latitude plants), with the majority of taxonomic losses occurring over a few tens of thousands of years, approximately 251.9 million years ago. In the marine realm, more actively motile animal groups fared relatively better during the extinction. Reef ecosystems were particularly hard‐hit. The primary causes of the marine extinction were ocean warming, acidification and expansion of low‐oxygen water, ultimately triggered by CO 2 released by Siberia Traps flood basalt volcanism. The terrestrial extinction was also caused by global warming and the resulting dry conditions and perhaps acid rain or ozone destruction and enhanced UV radiation. It took an unusually long time (5–7 million years) for most marine and terrestrial ecosystems to recover from the extinction, likely because of continuing intermittent stress. The extinction triggered permanent changes in the composition and structure of marine ecosystems, giving rise to mollusc‐dominated communities that remain dominant today.