The end of the Cretaceous period witnessed one of the most dramatic mass extinctions in Earth's history. Find out what caused the extinction of dinosaurs and many other animals. The fossil record shows that during the first 175 million years of their existence, dinosaurs took on a variety of forms as their environments changed and new species evolved to adapt to these new conditions. Dinosaurs that failed to adapt became extinct. But 66 million years ago, in a relatively short period of time, the dinosaurs completely disappeared (except for birds). Many other animals also became extinct, including pterosaurs, large marine reptiles, and ammonoids.
Strong evidence shows that a huge asteroid impact caused the mass extinction of the dinosaurs 66 million years ago.
Although the numbers of dinosaur species were already declining, this suggests that a sudden catastrophic event sealed their fate - causing adverse changes in the environment faster than dinosaurs and other creatures could adapt.
What was the cause of the Cretaceous mass extinction?
The exact nature of this catastrophic event remains subject to scientific debate. There is evidence that an asteroid impact is to blame. Volcanic eruptions that cause large-scale climate changes, as well as more gradual changes in Earth's climate over millions of years, may also be involved.
Whatever the cause, the mass extinction that ended the age of the dinosaurs left a void in ecosystems around the world. These areas were then filled by the only surviving dinosaurs - birds - and mammals, both of which evolved rapidly.
