Transition States Of Biochemical Processes -

permian triassic extinction event wikipedia - 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