Comet, not Asteroid Drove Dinosaurs to Extinction

One of the greatest mysteries in science till date is the extinction of dinosaurs that dominated the Earth for more than 150 million years.

This mystery is solved by the latest study which claims that the rocky object that drove dinosaurs to extinction 65 million years ago was in fact a speeding comet and not an asteroid, reports LiveScience.

According to the study conducted by lead author Jason Moore, a paleoecologist at Dartmouth College in New Hampshire, the 180-km-wide Chicxulub crater on the Yucatan Pennisula in Mexico was carved due to the impact of a faster, smaller object than previously thought. Prior to this, many scientists had believed that it was an asteroid that was responsible for the extinction of dinosaurs.

"The overall aim of our project is to better characterise the impactor that produced the crater in the Yucatan peninsula [in Mexico]," Moore was quoted as saying in BBC News.

The space rock's impact produced a global layer of sediments that had a high quantity of chemical element iridium. The concentration was strong, and doesn't occur in such high quantities on Earth naturally.  According to the latest finding, the previously quoted iridium values were not apt.

On comparing the values with the levels of osmium, another extraterrestrial element that was deposited during the impact, the researchers concluded that the space rock produced less debris than what was previously assumed, thus indicating that the space rock was a smaller object. And for such a small space rock to create a 180-km-wide crater, it should have been travelling exceedingly fast.

"You'd need an asteroid of about 5km diameter to contribute that much iridium and osmium. But an asteroid that size would not make a 200km-diameter crater. So we said: how do we get something that has enough energy to generate that size of crater, but has much less rocky material? That brings us to comets, " Moore was quoted as saying in BBC.

But there are a few from the scientific community that do not agree with Moore's proposal.

Dr. Gareth Collins, a researcher of impact cratering at Imperial College London who appreciated the team on their findings, somehow didn't approve of their conclusion, stating that the findings are debatable. According to him, it is not possible to accurately determine the size of the impactor based on geochemistry, because geochemistry just gives the mass of the meteoritic material that is distributed globally and not the total mass of the impactor, reports LiveScience.

The researchers state that 75 percent of the space rock mass was scattered on Earth, but Collin argues that it could have been less than 20 percent, which came from a large and slower asteroid.

The study is presented this week at the 44th Lunar and Planetary Science Conference in The Woodlands, Texas.