A team of scientists says evidence from fossilized leaves indicates that dinosaurs appear to have become extinct as a result of the catastrophic impact of an asteroid and not volcanic activity.

Dinosaurs, along with an estimated 70 percent of all life on Earth, are believed to have gone extinct 65 million years ago as a result of a series of dramatic temperature changes. The extinctions are known as the K-T extinctions because they fall on the boundary between the Cretaceous (geological symbol K) and the Tertiary periods.