Not one, but two asteroids might have slain the dinosaurs

An 8.5-kilometer-wide craterlike structure lies hundreds of meters beneath the seafloor

An illustration of a huge asteroid crashing into ocean. An ancient sea creature is visible under the water

Buckled terrain on the seafloor just off the coast of West Africa may have been formed by a 400-meter-long asteroid crashing into the ocean at about the same time as the impact that wiped out the dinosaurs (illustrated).

MARK GARLICK/SCIENCE PHOTO LIBRARY/Getty Images Plus

Chicxulub, the asteroid that wiped out most dinosaurs, might have had a little sibling.