Did a collision with a giant asteroid or comet change the shape of life on Earth forever? It is widely agreed that such an object -- 10 kilometers across -- struck just off the coast of the Yucatan ...

Nearly 66 million years ago, a large asteroid hit Earth and contributed to the global extinction of dinosaurs, allowing the rise of mammals and leaving birds as their only living descendants.

The sky burned with streaks of crimson red and dark orange. The dinosaurs looked up — just in time to see a burning, bright flash streak across the sky. Then the asteroid hit, wiping out ...

It is one of the greatest puzzles in paleontology. For more than 150 million years, dinosaurs dominated Earth. They were so successful that other animal groups -- mammals included -- had little chance ...