Mass-extinction meaning

The extinction of a large number of species within a relatively short period of time, as between the Cretaceous and Tertiary Periods when three-quarters of all species on earth, including most dinosaurs, became extinct.
noun
1
0
The extinction of a large number of species within a relatively short period of time, as between the Cretaceous and Tertiary Periods when three-quarters of all species on earth, including most dinosaurs, became extinct.
noun
0
0
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.
0
0
(biology) A sharp decrease in the total number of species in a relatively short period of time.
noun
0
0
Advertisement