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Dinosaur extinction: scientists come up with most precise date yet


A visitor looks at a the skull of a Tyrannosaurus rex at the all-new 14,000 square foot Dinosaur Hall permanent exhibition at the Natural History Museum of Los Angeles July 7, 2011.


Robyn Beck

An international team of scientists has come up with the most precise date yet for the extinction of the dinosaurs, BBC News reported. Their radiometric dating analysis of rock and ash samples indicates that the dinosaurs died out 66,038,000 years ago, plus or minus 11,000 years.

The findings of the researchers, from the Berkeley Geochronology Center and the University of California at Berkeley in the US, Glasgow University in the UK and Vrije University Amsterdam in the Netherlands, appear in the Feb. 8 issue of the journal Science.

The new extinction date supports the theory that the Cretaceous-Tertiary extinction event, which killed off all dinosaurs except the birds, was caused by an asteroid or comet slamming into what is now Mexico, BBC News reported. The revised date is no more than 33,000 years after an asteroid collision created a 110-mile-wide crater near the Mexican town of Chicxulub.

According to LiveScience:

The explosion, likely caused by an object about 6 miles (10 km) across, would have released as much energy as 100 trillion tons of TNT, more than a billion times more than the atom bombs that destroyed Hiroshima and Nagasaki.

"We've shown the impact and the mass extinction coincided as much as one can possibly demonstrate with existing dating techniques," researcher Paul Renne, a geochronologist and director of the Berkeley Geochronology Center in California, told LiveScience.

While the asteroid collision wasn’t the only event that killed off the dinosaurs, "the impact was clearly the final straw that pushed Earth past the tipping point,” Renne said, according to BBC News.

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