A new Stanford-led study has identified metabolism as the key factor determining which marine species survived Earth's largest mass extinction 252 million years ago. The research shows that animals unable to cope with warmer, low-oxygen waters perished at higher rates. Survivors with higher energy demands went on to dominate modern oceans.
The Permian-Triassic extinction, known as the Great Dying, eliminated about 96 percent of marine species. Before the event, brachiopods dominated seafloors for 280 million years. Afterward, mollusks such as clams and snails took over.
Published July 6 in the Proceedings of the National Academy of Sciences, the study combined data from both extinct and surviving groups. Lead author Jose Andres Marquez said the findings explain why beachgoers today find clam and snail shells rather than brachiopods. Senior author Erik Anders Sperling called the work the final evidence linking the extinction to volcanic-driven warming and oxygen loss.
The team measured oxygen use in living species under varying temperatures. Paleozoic animals struggled when temperatures rose because their metabolisms could not meet increased oxygen needs. Sperling noted that modern oceans face similar risks but added that action remains possible to limit warming.