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5 December 2013 11:26 am ,
Vol. 342 ,
An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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ScienceShot: Big Smash, Dead Dinos
7 February 2013 2:00 pm
Evidence that the impact of a kilometers-wide asteroid ravaged Earth's ecosystems and wiped out the dinosaurs millions of years ago is now stronger than ever. Using a high-resolution dating technique that measures the ratios of two argon isotopes, researchers analyzed 14 samples of material that had been flung from the impact site just north of the Yucatán Peninsula. Those dates, when combined with similar analyses reported previously, pin down the event—dubbed the Chicxulub impact after a small Mexican village closest to the offshore impact site—to approximately 66,038,000 years ago. And argon-argon dating of volcanic ash samples unearthed in Montana (image) from a bed of coal lying just a few centimeters above the iridium-rich layer deemed to contain fallout from the asteroid impact—and just 5 cm above rocks containing large amounts of dino-era pollen—suggests that mass extinctions occurred about 66,043,000 years ago. Considering the statistical errors in the two analyses, the impact and the dino die-offs may have occurred at the same time, or they may have occurred no more than 32,000 years apart, the researchers report online today in Science. Regardless, the team says, the new results certainly knock a hole in the notion that the mass extinctions, including the dinosaurs, occurred as much as 300,000 years before the asteroid impact, which some other researchers have contended for decades.
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