Image courtesy of NASA shows an artist's concept of a broken-up asteroid. Scientists think that a giant asteroid, which broke up long ago in the main asteroid belt between Mars and Jupiter, eventually made its way to Earth and led to the extinction of the dinosaurs. Credit: Reuters/NASA/JPL-Caltech/Handout
(Reuters) – Dinosaurs died off about 33,000 years after an asteroid hit the Earth, much sooner than scientists had believed, and the asteroid may not have been the sole cause of extinction, according to a study released Thursday.
Earth's climate may have been at a tipping point when a massive asteroid smashed into what is now Mexico's Yucatan Peninsula and triggered cooling temperatures that wiped out the dinosaurs, researchers said.
The study, based on high-precision radiometric dating techniques, said the events occurred within 33,000 years of each other.
Other scientists had questioned whether dinosaurs died before the asteroid impact.
"Our work basically puts a nail in that coffin," geologist Paul Renne of the University of California Berkeley said.
The theory that the dinosaurs' extinction about 66 million years ago was linked to an asteroid impact was first proposed in 1980. The biggest piece of evidence was the so-called Chicxulub (pronounced "cheek'-she-loob") crater off the Yucatan coast in Mexico.
It is believed to have been formed by a six-mile-(9.6-km-) wide object that melted rock as it slammed into the ground, filling the atmosphere with debris that eventually rained down on the planet. Glassy spheres known as tektites, shocked quartz and a layer of iridium-rich dust are still found around the world today.
Renne and colleagues reanalyzed both the dinosaur extinction date and the crater formation event and found they occurred within a much tighter window in time than previously known. The study looked at tektites from Haiti, tied to the asteroid impact site, and volcanic ash from the Hell Creek Formation in Montana, a source of many dinosaur fossils.
NEW DATING TECHNIQUE
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