The time of the dinosaurs spanned between two huge extinction events. The Permian-Triassic extinction at 252 million years ago was absolutely nuts, somewhere like 95% of marine species and 70% of terrestrial species would vanish, making it the worst extinction event in earth’s history. The Cretaceous-Paleogene at 66 million years ago was a little less severe, ‘only’ 75% of earths species would go extinct. The earth has gone through 5 mass extinction events, with a lot of scientists saying we are now entering a sixth. The cause of all these extinction events has been climate change. The dinosaur extinction is associated with a meteorite, the Permian extinction with the release of gases from the volcanic Siberian traps. A meteorite or volcanic event might have been the catalyst for extinction, but it was the environmental climate change in the aftermath of those events that truly caused the mass extinctions.