Permian–Triassic extinction event
mass extinction event at the end of the Permian Period approximately 250 million years ago
The Permian–Triassic extinction event, colloquially known as the Great Dying, was an extinction event that occurred around the boundary between the Permian and Triassic geologic periods, and with them the Paleozoic and Mesozoic eras. It is Earth's most severe known extinction event, with the extinction of 57% of biological families, 62% of genera, 81% of marine species, and 70% of terrestrial vertebrate species. It is also the greatest known mass extinction of insects. It is the greatest of the "Big Five" mass extinctions of the Phanerozoic. There is evidence for one to three distinct pulses, or phases, of extinction, with the major pulse of marine extinction occurring in a 60,000-100,000 year interval around 251.902 million years ago (mya) marking the boundary between the Permian and Triassic periods. There is some controversy regarding the chronology of the extinctions on land and whether they are synchronous with the main marine extinction event.
The scientific consensus is that the main cause of the extinction was the flood basalt eruptions that created the Siberian Traps, which released sulfur dioxide and carbon dioxide, resulting in euxinia (oxygen-starved, sulfurous oceans), elevated global temperatures,
and acidified oceans.
The level of atmospheric carbon dioxide rose from around 400 ppm to 2,500 ppm with approximately 3,900 to 12,000 gigatonnes of carbon being added to the ocean-atmosphere system during this period.
Several other contributing factors have been proposed, including the emission of carbon dioxide from the burning of oil and coal deposits ignited by the eruptions;
emissions of methane from the gasification of methane clathrates; emissions of methane by novel methanogenic microorganisms nourished by minerals dispersed in the eruptions; longer and more intense El Niño events; and an extraterrestrial impact that created the Araguainha crater and caused seismic release of methane and the destruction of the ozone layer with increased exposure to solar radiation.
Dating
Previously, it was thought that rock sequences spanning the Permian–Triassic boundary were too few and too incomplete for scientists to reliably determine their details.
This brief starts where responsible research should: with the source description of “Permian–Triassic extinction event” as mass extinction event at the end of the Permian Period approximately 250 million years ago. Everything that follows is an evidence route, not borrowed authority.
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The subject matters to the history & society register because the source frames it as mass extinction event at the end of the Permian Period approximately 250 million years ago. Its deeper value depends on whether names, dates, institutions and citations support that framing.
The record creator and administrative purpose are central evidence, because official documentation reflects both action and institutional priorities. The source revision retrieved here is dated Sep 19, 2026. The linked authority identifier is Q141118. The Library of Congress control number is sh2020001106. 1 of 1 selected statements include explicit references; 1 carry qualifiers and 0 use preferred rank.
Later summaries often reconcile disputed chronology or motive more neatly than the contemporary record permits. The source lead contains qualifying language; that uncertainty should survive quotation, summary and reuse. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
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This entry incorporates text from “Permian–Triassic extinction event” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.