Approximately 251.9 million years ago, the Permian–Triassic (P–T, P–Tr) extinction event (PTME; also known as the Late Permian extinction event, the Latest Permian extinction event, the End-Permian extinction event, and colloquially as the Great Dying) forms the boundary between the Permian and Triassic geologic periods, and with them the Paleozoic and Mesozoic eras. It is Earth's most severe known extinction event, with the extinction of 57% of biological families, 83% of genera, 81% of marine species and 70% of terrestrial vertebrate species. It is also the greatest known mass extinction of insects. It is the greatest of the "Big Five" mass extinctions of the Phanerozoic. There is evidence for one to three distinct pulses, or phases, of extinction.
approximately 2519 million years ago the permian–triassic (p–t p–tr) extinction event (ptme; also known as the late permian extinction event the latest permian extinction event the end-permian extinction event and colloquially as the great dying) forms the boundary between the permian and triassic geologic periods and with them the paleozoic and mesozoic eras it is earth's most severe known extinction event with the extinction of 57% of biological families 83% of genera 81% of marine species and 70% of terrestrial vertebrate species it is also the greatest known mass extinction of insects it is the greatest of the "big five" mass extinctions of the phanerozoic there is evidence for one to three distinct pulses or phases of extinction