Researchers link the mass extinction of once-dominant marine groups to intolerable heat, diminished oxygen in oceans

Article excerpt

A new Stanford-led study offers the clearest picture yet of how some ocean life survived our planet's biggest mass extinction while most animals did not. About 252 million years ago, 96% of marine species and 70% of land animals died off during the Permian, Triassic extinction event, known as the "Great Dying." Not all branches of the evolutionary tree were affected evenly, however.