Volcanoes to Blame for Dinosaur Die-Offs?

Volcanoes may be to blame, at least in part, for the dinosaur die-off that occurred 66 million years ago, according to a new study, despite the widely held belief that a catastrophic meteor strike led to their extinction.

In what is known as the Deccan Traps, a series of volcanic eruptions left 123,000 cubic miles (512,000 cubic kilometers) of what is now India covered in molten hot lava up to a mile and a half thick. And the gases spewed out by those eruptions, researchers say, could have made Earth inhospitable for the dinosaurs by changing temperatures and ocean acid levels, leading to their demise.

However, until now scientists did not know when India's Deccan Traps began and how long they lasted. The new findings, published in the journal Science, could prove that volcanoes caused the Cretaceous-Paleogene extinction.

"Now we can say when the Deccan Traps started," lead study author Blair Schoene, a geologist at Princeton University, told Live Science. "For me, it's not whether the impact or the Deccan traps caused the extinction. The point is that without a precise timeline, you can't understand what happened."

Schoene and his colleagues finally determined the age of the Deccan Traps with an exhaustive search for zircons, tiny minerals that are rarely found in basalt lavas. Analysis of the zircons indicates that the youngest lava flows emerged 66.29 million years ago, about 250,000 years before the Chicxulub impact crashed into eastern Mexico's Yucatan Peninsula. They lasted for about 750,000 years after that.

And while the researchers aren't suggesting that volcanoes alone wiped out the dinosaurs, they do believe that their climate-altering effects were already putting a huge amount of stress on many species, setting them up for disaster.

"What we do know," Schoene told Time magazine, "is that earlier mass extinctions were caused by volcanic eruptions alone."

For example, research by Paul Renne, who was not involved in this study, links huge flood basalts in Siberia to the Permian period's Great Dyingwhen 95 percent of all species on Earth went extinct.

Researchers may not yet know the exact mechanism of how the Deccan Traps caused an incredible outpouring of lava, but with the new dates of start and end, it puts an interesting twist on the conventional impact theory.

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