Permian–Triassic extinction event

The Permian–Triassic extinction event, colloquially known as the Great Dying, was an extinction event that occurred around 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, 62% of genera, 81% of marine species, and 70% of terrestrial vertebrate species.

Source: Wikipedia — Permian–Triassic extinction event (CC BY-SA 4.0)