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 exhibited a wide variety of forms as the environment changed and new species evolved to adapt to these new conditions. Those that failed to adapt went extinct. But 66 million years ago, in a relatively short period, dinosaurs (except for birds) completely disappeared. Many other animals also went extinct, including pterosaurs, large marine reptiles, and ammonites.
Strong evidence suggests that a massive asteroid impact 66 million years ago led to the mass extinction of the dinosaurs.
Although the number of dinosaur species was already declining, this suggests that a sudden catastrophic event determined their fate—causing adverse environmental changes that outpaced the adaptability of dinosaurs and other organisms.
What caused the Cretaceous-Paleogene extinction event?
The exact nature of this catastrophic event remains to be debated scientifically. There is evidence that an asteroid impact was the culprit. Volcanic eruptions causing large-scale climate change, and more gradual changes in Earth's climate over millions of years, may also be related.
Whatever the reason, the mass extinction that ended the age of dinosaurs left voids in ecosystems around the world. Subsequently, the only surviving dinosaurs—birds—and mammals filled these areas, both of which evolved rapidly.
