London: A new study has suggested that dinosaurs were killed 65 million years ago by at least two meteorite impacts, rather than a single strike.
Previously, it was thought that the Chicxulub Crater in the Gulf of Mexico lead to the extinction of dinosaurs from the earth. But now evidence for a second impact in Ukraine has been uncovered.
The discovery of the Boltysh Crater has suggested that the dinosaurs were driven to extinction by a "double whammy" rather than a single strike.
In the current study, scientists examined the "pollen and spores" of fossil plants in the layers of mud that unfilled the crater.
They found that immediately after the impact, ferns quickly colonised the devastated landscape.
Ferns have an amazing ability to bounce back after catastrophe. Layers full of fern spores - dubbed "fern spikes" - are considered to be a good "markers" of past impact events.
They located a second "fern spike" in a layer one metre above the first, suggesting another later impact event.
"We interpret this second layer as the aftermath of the Chicxulub impact," the BBC quoted Simon Kelley of the Open University as saying.
This shows that the Boltysh and Chicxulub impacts did not happen at exactly the same time. They struck several thousand years apart, the length of time between the two "fern spikes".
Kelley continued: "It is quite possible that in the future we will find evidence for more impact events".
Professor Monica Grady, a meteorite expert at the Open University said: "One possibility might be the collision of Near Earth Objects."
The new findings have been published in the journal Geology by a team lead by David Jolley of Aberdeen University.
First Published: Tuesday, August 31, 2010, 08:49