A geologist and an ecologist have joined forces to research the history of mass extinctions on Earth, and they've come to a conclusion: Most or all of the mass extinctions of the last 260 million years were caused by comet and asteroid showers.
For years, scientists have studied impact craters in the Earth that were likely caused by comets and asteroids, but have not been able to conclusively say that they were the definitive cause of mass extinctions, like that of the dinosaurs.
But in the new paper written by Michael Rampino, a New York University geologist, and Ken Caldeira, an ecologist for the Carnegie Institution, the experts unveil new findings that date the craters to the same time as the five major mass extinctions. They also found that six of the biggest craters are all correlated with periods of heavy comet and asteroid activity.
"The correlation between the formation of these impacts and extinction events over the past 260 million years is striking and suggests a cause-and-effect relationship," said Rampino, in a press release.
In the past, age estimates for these impacts were general, so comparisons with mass extinctions were tenuous at best. But newly available data allowed the scientists to run better and more exact time analyses, leading them to believe comets and asteroids struck Earth each time one of the mass extinction events is known to have happened. That would be quite a coincidence, if the objects didn't cause the extinctions.
One of the most famous craters on Earth, the Chicxulub impact structure in the Yucatan, which is about 112 miles across, was analyzed for the study. It was found to be about 65 million years old, which every Spielberg fan knows is the era of the death of the dinosaurs and their contemporaries.
Just 30 years ago, the findings would have been controversial at best, and laughed at, at worst. But as data mounts, the case for collision grows.
Rampino and Caldeira published their findings in the Monthly Notices of the Royal Astronomical Society.
Photo: Mike Beauregard | Flickr
