The Asteroid Impact
About 66 million years ago, a massive asteroid roughly 6 miles wide struck Earth near what is now the Yucatan Peninsula in Mexico. The impact created the Chicxulub crater and released energy equivalent to billions of atomic bombs. This collision was powerful enough to cause earthquakes, tsunamis, and massive explosions across the planet.
Climate Change After Impact
The asteroid impact threw enormous amounts of dust, ash, and smoke into Earth's atmosphere, blocking out sunlight for months or even years. Without sunlight, temperatures dropped drastically, plants died, and the food chain collapsed. Dinosaurs, which were large animals that needed lots of food, could not survive these harsh conditions.
Volcanic Activity
Around the same time as the asteroid impact, massive volcanic eruptions were occurring in what is now India. These volcanoes released gases and ash that also contributed to climate change and made survival even more difficult for dinosaurs. Scientists believe the combination of the asteroid impact and volcanic activity together sealed the fate of dinosaurs.
Which Animals Survived
While dinosaurs died out, some animals did survive the extinction event. Birds are actually considered living dinosaurs by scientists because they evolved from theropod dinosaurs. Mammals, crocodiles, turtles, and some reptiles also survived and eventually thrived after dinosaurs disappeared. 
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