Science / Medicine : New Clues to Dinosaurs’ End

Scientists say they have found new evidence that a worldwide fire, triggered by a meteorite impact, contributed to widespread extinctions of dinosaurs and other life forms 65 million years ago. The evidence comes from close examination of ancient clay samples from five sites in Europe and New Zealand, the researchers said in the British journal Nature.

The hypothesis had been proposed in 1985 on the basis of similar studies. It built on a suggestion that a huge object crashed into Earth about 65 million years ago.

The impact is hypothesized to have kicked up enough dust to block sunlight for a long time, triggering extinctions by lowering temperatures and killing vegetation.

A worldwide fire could have added other dangers, said University of Chicago chemist Edward Anders, a co-author of the new study. Apart from burning or choking in the flames, organisms could have perished from newly formed toxic compounds or from an eventual warming of temperatures triggered by carbon monoxide that the fire poured into the atmosphere, he said.