An asteroid impact, not volcanism, may have made Earth unlivable for dinosaurs

New simulations add to evidence that the Chicxulub strike is what killed T. rex and its kin

Earth about to be hit by asteroid

When a 10- to 12-kilometer-wide asteroid (bright light in this illustration) struck what is now the Yucatán Peninsula in Mexico 66 million years ago, it pulverized tons of Earth’s crust, sending a humongous cloud of dust into the sky and blocking out the sun for decades.

Gabriele Chiarenza

For decades, scientists have gone back and forth about whether massive volcanic eruptions or an asteroid impact — or maybe both — caused a mass extinction that saw the demise of all nonbird dinosaurs about 66 million years ago.