Scientists Identify Rare CO Chondrite as Dinosaur Killer

Scientists have identified the specific type of meteorite that struck Earth 66 million years ago, triggering the mass extinction that wiped out the nonavian dinosaurs. New research concludes the impactor was a rare CO chondrite, a primitive class of meteorite that accounts for only a tiny fraction of rocks found on Earth.

The findings, published in the journal Science Advances, come from an international team of researchers from institutions including the University of British Columbia, Paris, Brussels, and Vienna. By analyzing nickel isotopes preserved in a thin, global layer of clay deposited after the impact, the scientists were able to match the chemical fingerprint to the rare carbonaceous meteorite class. This layer, known as the Cretaceous-Paleogene boundary, contains only minute traces of the original object, which largely vaporized upon impact.

The identification shifts a key detail in the understanding of the catastrophe. CO chondrites contain markedly lower amounts of volatile elements like sulfur compared to other meteorite groups. This composition makes it less likely that sulfur released directly from the meteorite itself was the primary driver of the global...