Study suggests volcanoes actually killed the dinosaurs

Feb. 25 (UPI) -- Roughly 66 million years ago, an asteroid or comet crashed down to the Earth's surface in what is now Chicxulub, Mexico, pushing dust and vapor into the atmosphere.

Around the same time, an enormous volcano erupted in India, spilling lava rock that covered 11,000 feet of land and released dangerous gases into the air.

Now, researchers have plotted a high-resolution timeline for the eruptions in India's Deccan Traps, reported in Friday's issue of Science, and suggest that these eruptions may have played a much larger role in the disappearance of dinosaurs.

"Everyone has heard that the dinosaurs died from an asteroid hitting the Earth," Princeton geoscientist Blair Schoene, an associate professor at Princeton University and study author, said in a news release. "What many people don't realize is that there have been many other mass extinctions in the last 500 million years, and many of them coincide with large volcanic outpourings."

To date the rocks, Schoene and a team of researchers collected zircon crystals at the site and carbon dated them to find out which landed before and after the Deccan Traps lava flows.

The researchers figured that the eruptions occurred in four pulses, two of which occurred before the mass extinctions. Right after those pulses, the researchers assume that the sulfur and carbon dioxide that emitted from the eruptions caused the climate to shift back and forth from hot to cold. This disturbance to the atmosphere, they say, may have lead to the extinction.

"In general, I think this paper is significant and interesting," said Pincelli Hull, an assistant professor of geology and geophysics at Yale University who didn't participate in the research and has argued against the volcano mass extinction theory. "The paper is a huge advance in timing the [Deccan Traps] eruptions, but how that relates to the timing of outgassing is still a major question that needs to be resolved to figure out exactly what the relevant roles of volcanism and impact were."

After the research, however, the Deccan scientists are even more certain than before that their volcano theory is the likely cause for mass extinction.

"Deccan volcanism is the most likely cause of the dinosaur mass extinction," said another of the study's authors, Gerta Keller of Princeton. "The Chicxulub impact may have contributed to their demise, though the timing and environmental effects of this impact still remain to be determined."