Dinosaurs Got a One-Two Punch from an Asteroid and Volcanoes that Caused the Mass Extinction

First Posted: Oct 01, 2015 05:37 PM EDT

It turns out that the asteroid wasn't the only thing that did in the dinosaurs. Scientists have found that dinosaurs suffered from a one-two punch of an asteroid impact and then erupting volcanoes triggered by the collision.

For years, researchers have debated the role of volcanism and the asteroid impact during the last mass extinction. One side claimed that the eruptions were irrelevant while the other side claimed that the impact was the one that wasn't such a major contributor to the extinction.

Now, new evidence includes the most accurate dates yet for the volcanic eruptions before and after the impact. This new evidence shows that the Deccan Traps lava flows, which at the time were erupting at a slower pace, doubled in output within 50,000 years of the asteroid or comet impact that is thought to have initiated the last mass extinction on Earth.

"Based on our dating of the lavas, we can be pretty certain that the volcanism and the impact occurred within 50,000 years of the extinction, so it becomes somewhat artificial to distinguish between them as killing mechanisms: both phenomena were clearly at work at the same time," said Paul Renne, the lead researcher, in a news release. "It is going to be basically impossible to ascribe actual atmospheric effects to one or the other. They both happened at the same time."

The impact abruptly changed the volcanoes' plumbing system. This, in turn, produced major changes in the chemistry and frequency of the eruptions. After this change, long-term volcanic eruptions delayed recovery of life for about 500,000 years after the KT boundary.

"If our high-precision dates continue to pin these three events-the impact, the extinction and the major pulse of volcanism-closer and closer together, people are going to have to accept the likelihood of a connection among them," said Renne. "The scenario we are suggesting-that the impact triggered the volcanism-does in fact reconcile what had previously appeared to be an unimaginable coincidence."

The findings are published in the journal Science.

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TagsAsteroid, Dinosaurs, Dinosaur, Mass Extinction, Extinction, Extinct, Volcano, volcanic eruption