Did volcanoes do in the dinos?

Geologists have long attributed the disappearance of the dinosaurs to a catastrophic asteroid impact. But some scientists wonder if other factors–like massive volcanic eruptions in present-day India–didn’t have a hand in it too. That idea is bolstered by new research that finds a spike in mercury around the time of the extinction. Learn more in my podcast for Scientific American.

65 million years ago, three quarters of species went extinct, including Tyrannosaurus rex, above. (Credit: Scott Robert Anselmo via Wikimedia)