Rex the Dinosaur Detective uses his heightened powers of observation to figure out scientific mysteries. His favorite mystery is what exactly killed the Dinosaurs around the Cretaceous–Paleogene boundary. The Chicxulub crater is the best evidence for what killed the dinosaurs 66 million years ago. It is a 100 mile crater in the Gulf of Mexico. It was created by a 6 mile wide asteroid that exploded a massive debris cloud that encircled the entire earth and created a thin layer of clay around the planet exactly on the CP boundry and it can still be seen today. It is that massive cloud that encircled the earth and killed all of the plant life and eventually all of the dinosaurs.