Rare CO‑chondrite identified as the meteorite that caused dinosaur extinction

An international research team analyzed high‑precision nickel isotope ratios in the thin clay layer deposited worldwide at the Cretaceous‑Paleogene boundary. Their results, published in *Science Advances*, point to a very rare type of carbonaceous chondrite—specifically a CO‑chondrite—as the impactor that created the Chicxulub crater and triggered the mass extinction 66 million years ago.

CO‑chondrites contain far fewer volatile elements such as sulfur, zinc, carbon and water than previously assumed impactors. The study therefore argues that the primary extinction driver was the massive plume of fine dust lofted into the atmosphere, which blocked sunlight for months to years, rather than sulfur‑derived cooling. "The fine debris ejected into the atmosphere was likely the main factor," said geologist Philippe Claeys.

The impactor, estimated to be 10–15 km wide, struck a shallow sea above present‑day Mexico’s Yucatán Peninsula at roughly 64 000 km/h, vaporising rock, generating a megatsunami and a blast wave that killed most life locally. Globally, the dust‑induced darkness caused a drastic temperature drop and a collapse of photosynthesis, contributing to the extinction of about 75 % of species, including all non‑avian dinosaurs.