<Li> Permian -- Triassic extinction event ( End Permian ) : 252 Ma at the Permian -- Triassic transition . Earth 's largest extinction killed 57 % of all families , 83 % of all genera and 90 % to 96 % of all species ( 53 % of marine families , 84 % of marine genera , about 96 % of all marine species and an estimated 70 % of land species , including insects ) . The highly successful marine arthropod , the trilobite , became extinct . The evidence regarding plants is less clear , but new taxa became dominant after the extinction . The `` Great Dying '' had enormous evolutionary significance : on land , it ended the primacy of mammal - like reptiles . The recovery of vertebrates took 30 million years , but the vacant niches created the opportunity for archosaurs to become ascendant . In the seas , the percentage of animals that were sessile dropped from 67 % to 50 % . The whole late Permian was a difficult time for at least marine life , even before the `` Great Dying '' . </Li>
<Li> Permian -- Triassic extinction event ( End Permian ) : 252 Ma at the Permian -- Triassic transition . Earth 's largest extinction killed 57 % of all families , 83 % of all genera and 90 % to 96 % of all species ( 53 % of marine families , 84 % of marine genera , about 96 % of all marine species and an estimated 70 % of land species , including insects ) . The highly successful marine arthropod , the trilobite , became extinct . The evidence regarding plants is less clear , but new taxa became dominant after the extinction . The `` Great Dying '' had enormous evolutionary significance : on land , it ended the primacy of mammal - like reptiles . The recovery of vertebrates took 30 million years , but the vacant niches created the opportunity for archosaurs to become ascendant . In the seas , the percentage of animals that were sessile dropped from 67 % to 50 % . The whole late Permian was a difficult time for at least marine life , even before the `` Great Dying '' . </Li>
what was the biggest mass extinction in geologic time
what was the biggest mass extinction in geologic time
Permian -- Triassic extinction event
Permian -- Triassic extinction event