Dinosaurs died within hours after impact

BOULDER, Colo., May 26 (UPI) -- U.S. scientists said new evidence suggests most of the dinosaurs were incinerated within hours after an asteroid impact 65 million years ago.

Scientists at the University of Colorado said the impact, which kicked up a global rain of fiery debris, quickly killed anything not underground or protected by water. The research builds on previous studies that concluded the die-off was rapid, they said, although some experts caution that the fossil record cannot determine the time of the die-off so precisely. It could have been years, they said.

For decades, most paleontologists have thought an asteroid was responsible for the death of the dinosaurs. Recently, a few scientists have argued that a combination of effects -- an asteroid along with perhaps increased volcanic activity and climate change, or even a second asteroid -- caused a slow demise of the giant animals.

The new research suggests, however, the energy of the impact was enough to cause the planet's normally blue sky to turn red-hot for hours, baking all unprotected creatures.