The Cretaceous-Tertiary extinction event, or the K-T event, is the name given to the mass extinction of the dinosaurs and other species that took place about 65 million years ago. For many years, paleontologists believed this event was caused by climate and geological changes that interrupted the dinosaurs' food supply. However, in the 1980s, father-and-son scientists Luis (1911-88) and Walter Alvarez (1940- ) discovered in the geological record, a distinct layer of iridium (an element found in abundance only in space) that corresponds to the precise time the dinosaurs died. This suggests that a comet, asteroid or meteor impact event may have caused the extinction of the dinosaurs. In the 1990s, scientists located the massive Chicxulub Crater at the tip of Mexico's Yucatán Peninsula, which dates to the period in question.
Dinosaurs roamed the earth for 160 million years until their sudden demise approximately 65 million years ago, in an event now known as the Cretaceous-Tertiary, or K-T, extinction event. ("K" is the abbreviation for Cretaceous, which is associated with the German word "Kreidezeit."). Besides dinosaurs, many other species of mammals, amphibians and plants died out at the same time. Over the years,