This handout focuses on the evidence for the theory that massive meteor impact off the coast of Mexico caused the mass extinction at the end of the Cretaceous Period.  The dinosaurs and about 75% of all marine invertebrate species and many other organisms died abruptly at this time.

It is part of a set of four articles on possible causes of the Permian and Cretaceous mass extinctions can be used to organize classroom debates or to have students compare and contrast the events and their causes.