The Toarcian Oceanic Anoxic Event occurred about 183 million years ago during the Early Jurassic period and represents possibly the most extreme case of widespread ocean deoxygenation of the entire Phanerozoic eon. It was triggered by massive volcanic eruptions from the Karoo-Ferrar large igneous province, which released enormous quantities of carbon dioxide, pushing atmospheric levels from roughly 500 to 1,000 parts per million and driving global warming of 3 to 7 degrees Celsius depending on location. The resulting warming intensified weathering, flooding the oceans with nutrients that caused eutrophication and oxygen depletion, devastating brachiopods and corals, of which about 91 percent of Tethyan species vanished, while numerous dinosaur groups and many plant communities on land also suffered losses. The event lasted about 500,000 years, with recovery spanning millions of years afterward.
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