When the cosmos shoots pool, it plays for keeps. It sunk a six-mile-wide rock in our pocket of the solar system 66 million years ago. The smack of the asteroid against Earth released energy on the order of billions of atomic bombs. Dinosaurs were the cataclysm's most famous victims, joined by sea creatures, plants and microorganisms. All told, Earth's biodiversity shrank by 75 percent in what is known as the Cretaceous-Paleogene, or K-Pg, extinction (also known as the K-T extinction).
A large asteroid strike happens only once every 100 million years. And a controversial new report suggests the K-Pg impact was an exceptionally unlikely shot. In a paper published Thursday in the journal Scientific Reports, a pair of researchers calculated the asteroid had little more than a 1-in-10 chance of triggering a mass extinction when it smacked into Earth. (We mammals should be glad it beat the odds: After the dinosaurs' swift exit, nocturnal furballs - our ancestors - scampered into the daylight and conquered the planet. And one branch of dinosaurs survived and persists as today's birds.)..