Answer:
Mass extinction is when biodiversity or species in a living habitat decreases to about three-fourths of its original number or to none. Such an event is identified by a sharp change in the diversity and abundance of multicellular organisms. It occurs when the rate of extinction increases with respect to the rate of speciation. Mass extinctions are usually associated with organisms that are macroscopic rather than microscopic. Examples of mass extinctions are Permian extinction of marine species, and Cretaceous extinction of various species, including dinosaurs.
