The asteroid that ended the age of dinosaurs may have been far rarer, drier and less sulfur-rich than scientists once thought. Traces buried in clay now point toward an unusual meteorite with roots in a distant part of the solar system. Nickel isotopes preserved at the boundary between the Cretaceous and Paleogene periods indicate that the Chicxulub impactor probably resembled a carbonaceous chondrite of the Ornans class, known as a CO chondrite. The findings came from researchers working in Paris, Brussels, Vienna and at the University of British Columbia. The team analyzed samples collected from impact clay layers in Denmark, Spain and Italy. CO chondrites represent a tiny fraction of meteorites recovered on Earth. They also contain fewer volatile substances, including carbon, zinc, water and sulfur, than several meteorite groups previously proposed as the Chicxulub projectile. Dr. Philippe Claeys, a visiting professor at the University of British Columbia, in front of an exhibit at the Pacific Museum of Earth. (CREDIT: University of British Columbia) “Carbonaceous chondrites of the Ornans class are definitely not like the …