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This is a drawing of the Chicxulub crater which was formed when a meteorite hit earth.
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Courtesy of NASA

New Blow for Dinosaur-Killing Asteroid Theory
News story originally written on April 27, 2009

The popular theory that the Chicxulub crater holds the clue to the demise of the dinosaurs might not be correct after all, according to a paper to be published in the Journal of the Geological Society on April 27, 2009.

The crater, discovered in 1978 in northern Yucatan and measuring about 180 kilometers (112 miles) in diameter, was caused by a massive extra-terrestrial impact. Particles from the impact have been found just below the Cretaceous-Tertiary (K-T) boundary, which is a geological feature that dates to the time at which the dinosaurs and many other species suddenly became extinct. This finding has made many scientists hypothesize that the impact at Chicxulub must have helped cause the dinosaursí demise.

However, new research by teams at Princeton University in New Jersey and the University of Lausanne, Switzerland, uses evidence from Mexico to suggest that the Chicxulub impact predates the K-T boundary by as much as 300,000 years.

The study found that there are four to nine meters of sediments separating the two events, and in these sediments they also found evidence that the Chicxulub impact probably didnít cause mass extinctions after all. At one study site, the researchers found 52 species present in sediments below the impact particle layer, and counted all 52 still present in layers above the particles, showing that not a single one of these species went extinct as a result of the Chicxulub impact.

The scientists suggest that the massive volcanic eruptions at the Deccan Traps in India may be responsible for the dinosaursí extinction, since they would have released huge amounts of dust and gases that could have blocked out sunlight and brought about an increased greenhouse effect.

Last modified March 20, 2010 by Jennifer Bergman.

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