For BBC World, BBC World, Updated: 28/08/2010
British scientists say that the disappearance of these animals could be due to the impact more than a meteorite.
"Illustration of a meteor impact on Earth (NASA)"
Dinosaurs disappeared from the face of the earth 65 million years because of the impact of at least two meteorites, not one weighed as far as a new study suggests.
Previously, scientists had identified a huge crater in the Gulf of Mexico, United States, which have been created by a meteorite impact that extinguished the dinosaurs.
Now a group of researchers claims that there is evidence of a second crash in Ukraine that might have something to do with the disappearance of these animals, suggesting that the Earth was bombarded by a meteor shower.
The new findings are published in the journal Geology by a team from the University of Aberdeen, United Kingdom, led by Professor David Jolley.
When in 1980 did the theory that a meteorite could have caused the extinction of the dinosaurs created considerable controversy.
Later, the discovery of the Chicxulub crater in the Gulf of Mexico was presented as evidence confirming the theory.
The discovery of a second crater in Ukraine suggest that the dinosaurs were extinguished by a double impact.
The study now published, the scientists examined the pollen and spores of plant fossils in the layers of mud from the crater and found that immediately after the impact, fern colonized the devastated landscape.
ferns have a remarkable capacity to recover after a disaster. Hence the strata full of fern spores are considered good indicators of past impacts.
However, scientists made an unexpected finding.
detected a second layer of the plants above it, suggesting a rear impact.
According to Professor Simon Kelley, co-author study, "the second layer is interpreted as the impact of Chicxulu." Rain
So meteorites, scientists believe that dinosaurs did not disappear because of a single impact, but a meteor shower that lasted for thousands of years.
What caused this bombardment is uncertain.
According to Professor Monica Grady, an expert in meteorites Universitat British Open could be due to the collision of near-Earth objects. Recently
U.S. Space Agency (NASA, for short) launched a program that aims to monitor these objects near the ground to create a warning system for potential future impacts.
Source: http://verde.latam.msn.com/articulo_bbc.aspx?cp-documentid=25381089
