Study: 6th mass extinction looms but preventable

Are humans causing a mass extinction on the magnitude of the one that killed the dinosaurs? Full story

Glaciers played role in ancient mass extinction

Nearly 500 million years ago, when nearly all life was still confined to the oceans, 85 percent of marine species disappeared. New research supports a theory that implicates a double punch of climate change. Full story

‘Rock-solid’ case: Asteroid killed the dinosaurs

After almost 20 years of debate, a blue-ribbon scientific panel says there's an "international consensus" that an asteroid impact caused a dinosaur-killing mass extinction 65 million years ago. Full story