From: Jennifer Chu | MIT News Office
Published December 12, 2014 08:38 AM

New insight from MIT on what killed off the dinosaurs

Sixty-six million years ago, an asteroid more than five miles wide smashed into the Earth at 70,000 miles per hour, instantly vaporizing upon impact. The strike obliterated most terrestrial life, including the dinosaurs, in a geological instant: Heavy dust blocked out the sun, setting off a cataclysmic chain of events from the bottom of the food chain to the top, killing off more than three-quarters of Earth’s species — or so the popular theory goes.

But now scientists at MIT and elsewhere have found evidence that a major volcanic eruption began just before the impact, possibly also playing a role in the extinction.

The team precisely dated rocks from the Deccan Traps — a region of west-central India that preserves remnants of one of the largest volcanic eruptions on Earth. Based on their analysis, the researchers determined that the eruption began 250,000 years before the asteroid strike and continued for 500,000 years after the giant impact, spewing a total of 1.5 million square kilometers of lava. 

The immense and long-lasting volcanism may have released dangerous levels of volatile chemicals into the air, poisoning the atmosphere and oceans.

“If models of volatile release are correct, we’re talking about something similar to what’s happening today: lots of carbon dioxide being emitted into the atmosphere very rapidly,” says Michael Eddy, a graduate student in MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS). “Ultimately what that can do is lead to ocean acidification, killing a significant portion of plankton — the base of the food chain. If you wipe them out, then you’d have catastrophic effects.”

Based on the new, more precise dates for the Deccan Traps, the researchers believe the massive eruptions may have played a significant role in extinguishing the dinosaurs — although the exact kill mechanism may never be known.

Image credit: Jose-Luis Olivares/MIT

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