Scientists identify rare CO chondrite as dinosaur-killing meteorite

A new study suggests that the impactor responsible for the mass extinction of the dinosaurs was not a typical carbonaceous asteroid but an exceptionally rare CO chondrite originating from a distant region of the solar system. Laboratory analysis of the Chicxulub impact layer reveals a chemical signature that differs markedly from previously identified impactors, indicating a composition rich in planet‑cooling dust and debris rather than the sulfur‑laden material commonly associated with such events.

The researchers argue that the unusual chemistry of the CO chondrite points to a mechanism in which the delivery of fine, volatile‑poor particles caused rapid atmospheric cooling and contributed to the catastrophic environmental changes that followed the impact. This finding reshapes the understanding of how the asteroid’s composition amplified its destructive power, offering fresh insight into the processes that led to the extinction of roughly 75 percent of Earth’s species 66 million years ago.