Scientists have determined that a rare CO chondrite meteorite struck Earth 66 million years ago, causing the mass extinction that eliminated the non-avian dinosaurs.
Researchers from the University of British Columbia, Paris, Brussels, and Vienna reached this conclusion through analysis of nickel isotopes in a global clay layer deposited after the Cretaceous-Paleogene impact. Their study, published in Science Advances, shows the impactor belonged to an uncommon class of carbonaceous chondrite with low levels of sulfur and other volatile elements.
Dr. Philippe Claeys noted that such meteorites contain far less sulfur than typical samples found on Earth. This evidence points to fine debris ejected into the atmosphere as the primary cause of global cooling rather than sulfur released by the asteroid itself.
The projectile measured 10 to 15 kilometers across and hit at approximately 64,000 kilometers per hour, forming the Chicxulub crater beneath Mexico's Yucatán Peninsula. Carbonaceous chondrites make up only about five percent of meteorites recovered on Earth, with CO chondrites representing an even smaller fraction.
The findings indicate the object likely originated from a distant outer region of the solar system or the asteroid belt near Jupiter.