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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Discover More

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

Example Sentences

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

From Science Daily

"This is the first time that we've been able to quantitatively examine the biogeography before and after a mass extinction event," explains Prof. Sallan.

From Science Daily

Who has time or energy for melting ice caps and mass extinction when day-to-day life is so catastrophic?

From Salon

Together, they document one of the earliest known expansions of land-dwelling animals into ocean ecosystems after a period of extreme global warming and mass extinction at the very beginning of the Age of Dinosaurs.

From Science Daily

Known as the end-Permian mass extinction, this event, often called the 'great dying', eliminated more than 90 percent of marine species.

From Science Daily