Permian Extinction 250 Millions years ago, which caused extinction of 95% of all living species in both animals & plants life. This extinctions was slow and took nearly 80000 years in 3 stages:
1- Increase in world temperature by 5 degrees Centigrade casued by super lengthy eruptions of Siberian Trapes
2-melting the frozen resoviours of Methan gas in the seabeds and releasing Carbon 12 (C12), which is a green house gas and raised sea temp by anothre 5 degrees, and that casued
3-world temp raised 10 degrees and that caused the mass extinctions
it took Earth millions of years to recover and after 20 millions years from then Dinosaurs first appeared.