🌊 Scientists Find Why Some Animals Survived Earth’s Worst Mass Extinction

About 252 million years ago, the Permian–Triassic extinction erased most marine species and permanently reshaped life in the oceans. A new Stanford-led study suggests that survival depended partly on how animals’ oxygen requirements changed as the water warmed.

Researchers measured oxygen consumption in living brachiopods and other animals representing the “Paleozoic” and modern marine faunas. At cooler temperatures, brachiopods could tolerate remarkably low oxygen levels. But as the water warmed, the minimum amount of oxygen they needed rose much faster.

Their slow metabolism was not the problem by itself. More active groups generally had muscles, gills and respiratory systems better able to supply additional oxygen under heat stress.

This may explain why brachiopods and crinoids were devastated, while bivalves, snails, fish and echinoderms suffered fewer losses and later came to dominate the oceans.

The extinction was therefore not completely random — but metabolism was not the only factor either. Warming and ocean deoxygenation acted through animals’ physiology, alongside stresses such as acidification.

Modern oceans are also warming and losing oxygen. The study does not predict another “Great Dying,” but it shows how strongly climate can favour some body plans over others.

Could the next reshuffling of ocean life be determined by which animals can keep breathing as the water heats up?

📄 Study: https://www.pnas.org/doi/10.1073/pnas.2533086123

#Paleontology #MassExtinction #MarineBiology #OceanWarming #ClimateChange