Stanford study reveals metabolic failure caused Earth's greatest extinction
Research indicates that the Great Dying was driven by the inability of slow-metabolizing marine life to adapt to rising temperatures and deoxygenation. These findings provide insight into how today's climate stressors may affect modern marine ecosystems.
A Stanford-led study has established that the metabolic demands of marine life dictated survival during the Permian–Triassic extinction event, the most severe environmental crisis in geologic time. Occurring 252 million years ago, the event—often termed the "Great Dying"—resulted in the disappearance of 96% of marine species and 70% of land animals. According to research published July 6 in the Proceedings of the National Academy of Sciences, the extinction favored animals capable of meeting high oxygen demands in a warming, deoxygenating ocean.
Before this catastrophe, ancient seafloors were dominated for approximately 280 million years by slow-moving, bottom-dwelling filter feeders such as brachiopods, sea lilies, and various corals. These organisms possessed slow metabolisms that were well-suited to the cool, oxygen-rich oceans of the Paleozoic era. However, the subsequent environmental collapse was driven by massive volcanic activity. This activity injected gargantuan amounts of carbon dioxide and methane into the atmosphere, causing rapid global warming.
The research, which involved comparing the metabolic responses of ancient fauna to those of modern mollusks, fish, and echinoderms, revealed a critical physiological divide. While Paleozoic creatures could survive in low-oxygen conditions under normal temperatures, their metabolisms could not keep pace as water temperatures rose. As their bodies demanded more oxygen to cope with the heat, these species proved unable to adjust, unlike their modern counterparts. Modern marine animals, such as clams, snails, and fish, possess the muscular and gill structures necessary to support higher activity levels and maintain metabolic function even as oxygen requirements shift.
"Our findings show that, across different organism groups, extinctions happened at much higher rates for those more vulnerable to increases in water temperature and decreases in oxygen availability."
Jose Andres Marquez, lead study author, via ScienceDaily
Complementary research utilizing fossilized brachiopod shells from the Southern Alps has further clarified the geochemical timeline of the event. By analyzing boron isotopes within these shells, researchers reconstructed seawater pH levels to trace the acidification directly to volcanic carbon degassing. This work, supported by the BASE-LiNE Earth project, suggests that the initial acidification and warming triggered a domino-like collapse of life-sustaining cycles, leading to widespread sulfide poisoning and deoxygenation of the oceans. The data indicates that the dissolution of methane hydrates, previously proposed as a potential contributor, was unlikely to be a significant driver of the extinction.
The ecological legacy of the Great Dying remains visible today. Brachiopods, which once vastly outnumbered bivalves, were nearly eliminated; today, only about 400 species remain, compared to the estimated 10,000 to 15,000 species of bivalves that emerged as the dominant successors.
"The biggest mass extinction of all time started from a world that is very similar to today in having a relatively cool, relatively well-oxygenated ocean, and then there was a giant injection of carbon dioxide into the Earth system. Understanding how Earth and Earth's biota responded back then could inform us of what's to come."
Erik Anders Sperling, senior author and associate professor at the Stanford Doerr School of Sustainability, via MirageNews
The researchers warn that the environmental trajectory of the modern era carries echoes of the Permian–Triassic crisis. While the Great Dying saw temperatures increase over thousands of years, current climate projections anticipate significant warming over a much shorter timeframe due to fossil fuel emissions. The team plans to continue studying how warming, oxygen loss, and acidification interact, as these stressors currently threaten modern marine ecosystems. The project was funded by the U.S. National Science Foundation, NASA, the Palaeontological Association, and the Stanford Woods Institute for the Environment.
