Is the 6th great extinction already upon us? The rate of species extinction is quicker now than at any point in the last 65 million years, when the cretaceous-tertiary (KT) extinction due to a meteor in Yucatan did for the dinosaurs. 75% of species disappeared. Prev extinctions cleared the way for the dinosaurs (Triassic-Jurassic, 205mya).  The worst (Permian-Triassic) wiped out 96% marine, 70% land species.