<P> The Permian -- Triassic ( P -- Tr or P -- T ) extinction event , colloquially known as the Great Dying , the End - Permian Extinction or the Great Permian Extinction , occurred about 252 Ma ( million years ) ago , forming the boundary between the Permian and Triassic geologic periods , as well as the Paleozoic and Mesozoic eras . It is the Earth 's most severe known extinction event , with up to 96 % of all marine species and 70 % of terrestrial vertebrate species becoming extinct . It is the only known mass extinction of insects . Some 57 % of all families and 83 % of all genera became extinct . Because so much biodiversity was lost , the recovery of life on Earth took significantly longer than after any other extinction event , possibly up to 10 million years . Studies in Bear Lake County near Paris , Idaho showed a quick and dynamic rebound in a marine ecosystem , illustrating the remarkable resiliency of life . </P>
<P> The Permian -- Triassic ( P -- Tr or P -- T ) extinction event , colloquially known as the Great Dying , the End - Permian Extinction or the Great Permian Extinction , occurred about 252 Ma ( million years ) ago , forming the boundary between the Permian and Triassic geologic periods , as well as the Paleozoic and Mesozoic eras . It is the Earth 's most severe known extinction event , with up to 96 % of all marine species and 70 % of terrestrial vertebrate species becoming extinct . It is the only known mass extinction of insects . Some 57 % of all families and 83 % of all genera became extinct . Because so much biodiversity was lost , the recovery of life on Earth took significantly longer than after any other extinction event , possibly up to 10 million years . Studies in Bear Lake County near Paris , Idaho showed a quick and dynamic rebound in a marine ecosystem , illustrating the remarkable resiliency of life . </P>
when did the permian mass extinction take place
when did the permian mass extinction take place
about 252 Ma ( million years ) ago
about 252 Ma ( million years ) ago