Volcanic eruptions may have been culling dinosaurs before an asteroid struck.
An illustration of dinosaurs fleeing a meteorite impact.
Illustration by Mark Garlick, Science Source
for National Geographic News
Published February 12, 2013
New insights about the asteroid thought to have killed off the dinosaurs suggest it may have just been the final blow, and that the reptiles were already suffering from a finicky climate prompted by volcanic eruptions long before the meteorite struck. "The [asteroid] impact was the coup de grace," Paul Renne, a geologist at the University of California, Berkeley, said in a statement. The research, detailed in the February 8 issue of the journal Science, adds to the ongoing scientific debate over what exactly killed off the dinosaurs. That debate, which once revolved around the question of whether the culprit was an asteroid or volcano-induced climate changes, has evolved to consider the possibility that perhaps multiple environmental factors were involved. Renne and his team recently determined the most precise date yet for the asteroid strike, which occurred in the Yucatán Peninsula in what is now Mexico. Using a high-precision dating technique on tektites—pebble-sized rocks formed during meteorite impacts—from Haiti that were created during the event, the team concluded that the impact occurred 66,038,000 years ago—slightly later than previously thought. When error limits are taken into account, the new date is the same as the date of the extinction, the team says, making the events simultaneous. Renne said the new findings should lay to rest any remaining doubts about whether an asteroid was a factor in the dinosaurs' demise. "We have shown that these events are synchronous to within a gnat's eyebrow," he said, "and therefore the impact clearly played a major role in extinctions." That is not to say, however, that the asteroid—which carved out the so-called...