The last five episodes of mass extinction appear to have occurred at the end of:
1
Cambrian, Silurian, Devonian, Carboniferous and Triassic
2
Cambrian, Triassic, Jurassic, Cretaceous and Tertiary
3
Ordovician, Devonian, Permian, Triassic and Cretaceous
4
Ordovician, Silurian, Carboniferous, Jurassic and Quaternary