<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 between 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 biological families and 83 % of all genera became extinct . Because so much biodiversity was lost , the recovery of land - dwelling life 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 relatively quick rebound in a localized marine ecosystem , taking around 2 million years to recover , suggesting that the impact of the extinction may have been felt less severely in some areas than others . </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 between 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 biological families and 83 % of all genera became extinct . Because so much biodiversity was lost , the recovery of land - dwelling life 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 relatively quick rebound in a localized marine ecosystem , taking around 2 million years to recover , suggesting that the impact of the extinction may have been felt less severely in some areas than others . </P>
during the permian extinction approximately what percent of all marine species were lost
during the permian extinction approximately what percent of all marine species were lost
96 %
96 %