New theory on dinosaurs' death
Artist's impression of the meteor impact which killed the dinosaurs
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Thursday, 24, Jan 2008 12:42
The event that caused the death of the dinosaurs 65 million years ago may have created more deadly effects than previously thought.
New three-dimensional images of the Chicxulub crater, which was formed when an asteroid struck the coast of the Yucatan Peninsula, suggest that the asteroid landed in deeper water than previously assumed.
This released about 6.5 times more water vapour into the atmosphere, according to Sean Gulick from the University of Texas.
The impact site also contained sulphur-rich sediments, which would have reacted with the water vapour to produce sulphate aerosols.
This in turn is likely to have had a cooling effect on the climate and to have generated acid rain.
Earlier studies also suggested these effects, but said they would have occurred to a lesser degree than the amount estimated by the latest research.
"The greater amount of water vapour and consequent potential increase in sulphate aerosols needs to be taken into account for models of extinction mechanisms," said Mr Gulick.
He argues that an increase in acid rain could explain why reef and surface-dwelling ocean creatures were affected along with large vertebrates on land and in the sea.
Acid rain combined with other environmental changes would have caused the mass extinctions, he added.
For example, dinosaurs could have been baked to death within hours or days of the impact as ejected material fell from the sky, heating the atmosphere.
The study is published journal Nature Geoscience.