News summary produced by Claude AI
Researchers at Stanford University have identified the primary mechanism behind the Permian-Triassic extinction event, often referred to as the “Great Dying,” which eliminated approximately 96% of marine species and 70% of land animals roughly 252 million years ago. The study, published July 6 in the Proceedings of the National Academy of Sciences, marks the first comprehensive analysis combining biological data from both groups that perished and those that survived the catastrophe.
The extinction was not uniformly distributed across marine life. Groups such as brachiopods, sea lilies, and other stationary seafloor dwellers dominated ocean ecosystems for approximately 280 million years before the event but were nearly eliminated afterward. In contrast, mollusks including clams and snails experienced roughly 50% species loss, while fish and echinoderms such as starfish and sea urchins fared better and subsequently came to dominate modern ocean ecosystems.
The research points to a single decisive factor: species whose metabolisms could not adapt to warmer, oxygen-depleted water experienced the highest extinction rates. The harsh oceanic conditions resulted from massive volcanic eruptions that released enormous quantities of carbon dioxide and methane into the atmosphere, causing rapid planetary warming. The study reveals that slow-moving, bottom-dwelling filter feeders prevalent during the Paleozoic era lacked the physiological capacity to survive these conditions, while more metabolically active species with greater oxygen-processing capabilities persisted.
Scientists conducted extensive fieldwork and laboratory experiments, collecting living brachiopods from Washington state’s San Juan Islands and measuring oxygen consumption across various marine organisms under different water temperature conditions. Results demonstrated that ancient species could tolerate lower oxygen levels but could not sustain increased metabolic demands as temperatures rose, unlike modern species equipped with more efficient muscular and gill structures.
The findings carry implications for contemporary ocean conditions. Researchers warn that current warming projections align with worst-case Permian-Triassic scenarios, though the rate of change differs significantly. While temperatures rose 8-12 degrees Celsius over thousands of years during the ancient extinction, modern projections indicate 1.5-4 degrees Celsius warming by 2100 within merely 100-200 years. Scientists emphasize that intervention remains possible to prevent similar ecological disruption in today’s oceans.