For 30 years the prevailing theory has been that dinosaurs were wiped out by a comet or asteroid crashing in Central America (marked by the 110-mile-wide crater, called Chicxulub), kicking up so much dust and ash that the Earth cooled for years afterward and made survival impossible. Still, some scientists said the timing was off. Radioactive dating suggested the comet impact was made 180,000 years after the last dinosaur fossils. Now a geologist from Berkeley has redefined the comet impact date.
Paul Renne, a geologist at the Berkeley Geochronology Center (BGC), along with colleagues from U.C. Berkeley as well as researchers from the UK and Netherlands, has resampled radio-isotope measurements from impact debris. It has been over two decades since the debris was analyzed to determine the impact date that theoretically doomed the dinosaurs. The new measurements narrow the strike date to a range of only 11 thousand years and put the disastrous date between 66.03 and 66.04 million years ago, making it virtually simultaneous with the extinction. According to Popular Science:
“There’s still good evidence to suggest that the catastrophe was preceded by several sharp climatic swings, which probably put a hurt on much of the life on Earth, but the new evidence leaves little doubt that the asteroid impact was, indeed, the proverbial nail in the dinosaur’s coffin.”