How We Found the Dinosaur Doomsday Site

When the impact hit Mexico's Yucatan Peninsula 66 million years ago, it wiped out most life on Earth. (Credit: NASA) On March 22, 1991, David Kring stood at a podium at the Lunar and Planetary Science Conference in Houston and revealed the exact location of the most important impact event in the past 100 million years. The dinosaur-killing space-rock struck Mexico’s present-day Yucatan Peninsula near the town of Chicxulub. By that time, most geologists already accepted Luis and Walter Alvarez’s once-wild theory that a 65-million-year-old, worldwide layer of iridium — a material common in asteroids, but not on Earth — implied an extinction event. But for a decade, scientists had tried and failed to find the crater. That led many to assume an impact in the deep ocean, which might explain the absence of a bowl as big as Connecticut. Kring didn’t buy it. His gut told him the Mount Everest-sized space rock struck closer to land. The path to proving it started along the banks of the Brazos River in Texas.