mass extinction

Scientific  

1. The extinction of a large number of species within a relatively short period of geological time, thought to be due to factors such as a catastrophic global event or widespread environmental change that occurs too rapidly for most species to adapt. At least five mass extinctions have been identified in the fossil record, coming at or toward the end of the Ordovician, Devonian, Permian, Triassic, and Cretaceous Periods. The Permian extinction, which took place 245 million years ago, is the largest known mass extinction in the Earth's history, resulting in the extinction of an estimated 90 percent of marine species. In the Cretaceous extinction, 65 million years ago, an estimated 75 percent of species, including the dinosaurs, became extinct, possibly as the result of an asteroid colliding with the Earth.

2. Compare background extinction

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mass extinction Cultural  

1. Any of several events in the Earth's past in which large numbers of species (in some cases, up to eighty percent) became extinct.

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The most famous mass extinction included the destruction of the dinosaurs sixty-five million years ago. (See Alvarez hypothesis.)

Example Sentences

See Examples For:

mass extinction

Scientists agree that we're living though the world's sixth mass extinction event, the first caused by humans.

From BBC ● Aug. 8, 2026

That balance changed dramatically after a mass extinction event eliminated much of the competition.

From Science Daily ● Apr. 15, 2026

Even after a catastrophic mass extinction, ecosystems can begin rebuilding within only a few thousand years, with new species emerging far sooner than scientists once thought.

From Science Daily ● Mar. 15, 2026

Bodenham's discovery adds another piece to the growing diversity of animals living in this region during the Late Triassic before the Triassic–Jurassic mass extinction event caused by an increase in volcanic activity altering the climate.

From BBC ● Feb. 17, 2026

Researchers had previously noted the temporal coincidence between the paleo-Indians’ arrival and the mass extinction, but they didn’t believe that small bands of hunters could wreak such ecological havoc.

From "1491" by Charles C. Mann