In Earth’s largest extinction, land animal die-offs began long before marine extinction: New dates for fossils indicate land animal turnover extended for hundreds of thousands of years 

Because of poor dates for land fossils laid down before and after the mass extinction at the end of the Permian, paleontologists assumed that the terrestrial extinctions from Gondwana occurred at the same time as the better-documented marine extinctions. But a new study provides more precise dates for South African fossils and points to a long, perhaps 400,000-year period of extinction on land before the rapid marine extinction 252 million years ago.

Source: In Earth’s largest extinction, land animal die-offs began long before marine extinction: New dates for fossils indicate land animal turnover extended for hundreds of thousands of years — ScienceDaily