With the dinosaurs finally here, and all the excitement and interest they bring, it's important to remember what really matters this holiday season: giant meteors falling from the sky.
Some paleontologists had long suspected that an impact may have spelled the end of the dinos, because their demise came so swiftly (geologically speaking). Some estimates suggested it took as little as 10,000 years to wipe them from the face of the Earth. It's so striking: we have rock formations that are infested with dinosaur bones below a certain line, and above it they're simply gone.
Another striking feature prompted a team led by physicist Luis Alvarez and his son, geophysicist Walter Alvarez, to propose the impact as a hypothesis in the early 1980's. Their reasoning came from iridium, which is rather rare in the Earth's crust, but is found in abundance in a thin layer separating dinosaur from not-dinosaur rocks. It's also found in asteroids.
Around the same time, but unknown to them, geophysicists working for the Pemex oil company discovered the half-submerged remnants of, you guessed it, a giant impact crater centered on the town of Chicxulub, Mexico. The crater is over a hundred miles wide and ten deep, and dates to the same age as the extinction event.
While other sources like the volcanic Deccan Traps and changing sea levels were causing stress on our dinosaur friends, and likely contributed to their downfall, there's little doubt that a 10 kilometer wide rock from space did some serious damage.