Saturday, March 9, 2019

Dinosaur Killers

From Scientific American:
What killed the dinosaurs? Scientists have long debated whether it was an asteroid that crashed into Earth 66 million years ago or a powerful wave of volcanic eruptions at that time. Two papers published today in Science say the real answer is— both, in a catastrophic coincidence. But the two teams of researchers disagree on a key point: whether the impact from space came first and boosted the eruptions into a climate-altering, dinosaur-killing frenzy, or whether they were two unrelated disasters with remarkably bad timing for the beasts that once stalked our planet and still stomp through our minds.

After decades of arguments between asteroid advocates and volcano boosters, in 2015 some scientists suggested both might be right, because an asteroid impact in Mexico—marked by a crater named Chicxulub—may have created seismic waves that shook the planet so violently that it sped up ongoing volcanic activity under India. That magma, in a region called the Deccan Traps, exploded in sunlight-dimming eruptions that chilled the climate, and then their release of carbon dioxide would have warmed it—a whiplash few creatures could survive. The idea was eruptions and impact together may have wiped-out the dinosaurs along with nearly 70 percent of species in a mass extinction at the end of the Cretaceous period. (Read more.)

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