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

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mass extinction

Instead, its new age places it close to the Frasnian-Famennian mass extinction event, which occurred about 372 million years ago and wiped out a large proportion of marine life on Earth.

From Science Daily ● Oct. 4, 2026

Hesperornithiforms were close evolutionary relatives of Neornithes, the branch that survived the mass extinction and eventually produced modern birds.

From Science Daily ● Sep. 11, 2026

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

From BBC ● Aug. 8, 2026

The end-Triassic mass extinction struck about 201 million years ago and has been tied to enormous volcanic eruptions associated with the break-up of Pangea.

From Science Daily ● Jul. 22, 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

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