A large asteroid (~12 km in diameter) hit Earth 66 million years ago, likely causing the end-Cretaceous mass extinction. Credit: Southwest Research Institute/Don Davis
Phys.org has a story on new research about the extinction of the non-avian dinosaurs. Since it's discovery 40 years ago by Walter and Luis Alvarez, this mass extinction, which occurred approximately 66 million years ago, has been a source for much research. The cause is generally thought to be the large meteor that struck the Earth and created the Chicxulub crater in Mexico. Now, some new evidence suggests that the ejecta from that strike caused the post event "Nuclear Winter", not widespread wildfires as had previously be suggested. A paper in the Proceedings of the National Academy of Sciences has the details.
A team of researchers from the U.S., Australia and the U.K. has found evidence that suggests material thrown into the atmosphere by the asteroid that struck the Earth approximately 66 million years ago, and not massive wildfires, led to a mass extinction event. In their paper published in Proceedings of the National Academy of Sciences, the group describes their study of sediment from the Chicxulub crater and other ocean areas and what it showed them.
Over the past several decades, Earth scientists have come to believe a large asteroid slammed into the Earth just off the coast of what is now Mexico's Yucatán Peninsula approximately 66 million years ago. The impact of the asteroid strike was so great that it led to a mass extinction event that killed off the dinosaurs. Evidence of the asteroid strike has been found around the globe, and so-called K–Pg boundary records have been identified. They are evidence of material in the atmosphere circling the globe after the asteroid strike, blocking out the sun, which resulted in plants and animals dying. But one area of contention has remained: the source of the material in K–Pg boundary records. Prior research has suggested it came from material that was burned by massive wildfires that were set off by the asteroid strike. In this new effort, the researchers suggest that while some of the material in K–Pg boundary records is likely from such burnt material, most of it came from material ejected from the crater at the impact site.