Date of dinosaur extinction fixed more accurately than ever before

The demise of the dinosaurs is the world's ultimate whodunit. Was it a comet or asteroid impact? Volcanic eruptions? Climate change? In an attempt to resolve the issue, an international team of scientists have determined the most precise dates yet for the dinosaur extinction 66 million years ago and for the well-known impact that occurred around the same time. The new extinction date is precise to within 11,000 years. In a paper published today in the journal Science, researchers from the Berkeley Geochronology Center (BGC), the University of California, Berkeley, the Scottish Universities Environmental Research Centre (University of Glasgow) and Vrije University, conclude that the dates of the events are so close that it's likely the impact of the comet or asteroid, if not wholly responsible for the global extinction, at least dealt the death blow to the dinosaurs. "The impact was clearly the final straw that provided the tipping point," said Paul Renne, BGC director and professor in residence of earth and planetary science at the University of California, Berkeley. "We have shown that these events are synchronous to within a gnat's eyebrow and therefore the impact clearly played a major role in extinctions, but it probably wasn't just the impact." The revised dates clear up lingering confusion over whether the impact actually occurred before or after the extinction, which was characterized by the almost overnight disappearance from the fossil record of land-based dinosaurs and many ocean creatures.