When did the Permian extinction occur?

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Line graph showing the number of marine animal families from the Precambrian era to the present, with illustrations of key groups such as trilobites, ammonoids, marine reptiles, and diatoms. The graph highlights major extinction events and a rise to 1,900 living families today. — Permian extinction The diversity of marine animal families since late Precambrian time. The data for the curve comprise only those families that are reliably preserved in the fossil record; the 1,900 value for living families also includes those families rarely preserved as fossils. The several pronounced dips in the curve correspond to major mass-extinction events. The most catastrophic extinction took place at the end of the Permian Period.

The Permian extinction, which represents the most severe mass extinction in Earth's history, occurred during the latter part of the Permian Period, which lasted from approximately 298.9 million to 252.2 million years ago.12

There is ongoing scientific debate regarding the duration of this event:

Extended duration: Many geologists and paleontologists suggest the extinction occurred over a span of 15 million years during the latter part of the period.3
Rapid duration: Other researchers argue the interval was much shorter, lasting approximately 200,000 years, with the majority of species loss occurring within a 20,000-year window near the end of the period.3

This event resulted in the loss of roughly 90 percent of all species on Earth.3