The extinction of the dinosaurs was pretty much extinction for everything, mosasaurs, plesiosaurs, pterosaurs, and dinosaurs, along with various other groups including Meat-eating crocodilians, freshwater sharks, and most species of a group of algae. Paleontologists believe dinosaurs went extinct because of a crater in the Yucatan Penninsula made by an asteroid called a Baptistina asteroid. The crater was made 65 million years ago, the exact time the dinosaurs went extinct. When Baptistina struck the Earth, the asteroid would have exploded with the force of 1,000,000,000 nuclear bombs. But with any extinction, no matter how bad, there are always survivors. Some birds, mammals, fish, amphibions, reptiles, and others were able to survive the explosion and the aftermath. But the most important surviver was a shrew-like mammal called Purgatorius. Purgatorius was the earliest primate, so we really would not here if Baptistina hadn't wiped out the dinosaurs. All modern life owes its exsistince to the exinction the wiped the Dinosaurs.Not All Dinosaurs Went Extinct. Birds are Dinosaurs.