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

A deep-water fish called coelacanth similarly survived the mass extinction that wiped out all the dinosaurs that did not evolve into birds, he pointed out.

From Barron's

Scientists have warned that Earth is currently going through another mass extinction -- this one caused by humans.

From Barron's

Almost a hundred new animal species that survived a mass extinction event half a billion years ago have been discovered in a small quarry in China, scientists revealed Wednesday.

From Barron's

This mass extinction, known as the Sinsk event, is thought to have been caused by declining oxygen levels.

From Barron's

"And the trend is clear - the mass extinction pulses led directly to increased speciation after several millions of years."

From Science Daily