Cretaceous-Tertiary (K-T) Mass Extinction Event

Perhaps the extinction event that is most familiar to you is one that happened approximately 65 million years ago. The extinctions that occurred at this time are known as the K-T (Cretaceous-Tertiary) extinctions. Many, but not all, species went extinct at this time - one such species was the dinosaur. While a large number of species went extinct worldwide, not all species went extinct.

The interactive lesson on the next page will provide you will several hypotheses scientists use to explain what caused the K-T extinctions and killed the dinosaurs. It also gives the key pieces of evidence scientists use to support each of these hypotheses.