Why the greatest mass extinction left us with seashells instead of brachiopods

Space · Published 21 October 2026 Swipe more like this →

In short: About 252 million years ago, the 'Great Dying' wiped out 96% of marine species. While many lineages vanished, others thrived. New research reveals that survival wasn''t random; it was a brutal test of metabolic endurance against a rapidly warming, oxygen-starved ocean.

The Permian–Triassic extinction event, occurring roughly 252 million years ago, was the most devastating biological catastrophe in Earth's history. During this era, the seafloor was dominated for approximately 280 million years by slow-moving, filter-feeding animals like brachiopods, sea lilies (crinoids), and certain corals. However, massive volcanic eruptions—specifically in what is now Siberia—released gargantuan amounts of carbon dioxide and methane into the atmosphere. This triggered intense global warming and a collapse of temperature gradients.

A recent study led by Stanford researchers, including J. Andres Marquez and Erik Anders Sperling, identifies metabolism as the decisive factor in survival. By comparing modern animals to ancient groups, scientists found that species with metabolisms unable to tolerate rising temperatures and dwindling oxygen levels suffered the highest extinction rates. While nearly all brachiopods and crinoids were eliminated, roughly half of mollusks, such as clams and snails, survived. These survivors, along with fish and echinoderms like starfish, went on to dominate the oceans.

New evidence also suggests that extreme climate variability, driven by prolonged El Niño-like events, exacerbated the crisis. Unlike modern El Niño events that typically last one to two years, the Permian–Triassic period saw persistent patterns of drought and flooding that lasted much longer, making adaptation nearly impossible for many species. This research serves as a warning: the current rapid injection of CO2 from human activities is creating environmental shifts strikingly similar to the conditions that preceded the Great Dying.

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