Researchers Identify Rare Meteorite That Killed Dinosaurs, Reshaping Extinction Story

EARTH, Laniakea Supercluster—Of all the rocks that could have fallen from the sky, the dinosaurs got one of the rarest in the cosmic catalog. Let’s call it bad luck, but on an extinction-level scale.

An international team made up of researchers from Paris, Brussels, Vienna, and the University of British Columbia (UBC) determined that the rock that crashed into the Yucatan Peninsula was an Ornans-class carbonaceous chondrite, known as a CO chondrite: a type of meteorite so rare that today it accounts for barely a fraction of the 5 percent of carbonaceous chondrites found on Earth. The findings were recently published in the journal Science Advances.

The key to identifying the killer lay in reading its chemical signature. The team analyzed high-precision nickel isotopes preserved in the clay deposits left by the impact across the globe—the so-called KT layer. It was a feat of forensics on a geological scale.

"Carbonaceous chondrites of the Ornans class are definitely not like the typical meteors you find in museum collections," stated Dr. Philippe Claeys, a visiting professor at UBC and a chair professor at Vrije Universiteit Brussel, in the UBC press release.

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That detail matters more than it might seem. The rock's chemistry rewrites part of the extinction story at the Chicxulub crater.

"A CO contains much less volatile elements—like carbon, zinc, water and particularly sulphur—than other classes of meteorites we've discovered so far on Earth," Claeys explained in the same release.

The subtext is that sulphur, long identified as the cataclysm's primary climate villain, may not have been the main culprit after all. According to the study, the projectile's low sulphur content suggests that it was the fine dust and debris ejected into the atmosphere (rather than the sulphur from the asteroid itself) that plunged the world into darkness and cold.

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Reconstructing all of this from next to nothing is a remarkable feat.

"This is challenging work. Only a minute fraction of the projectile is preserved in the planet's KT clay layer because the entire meteorite vaporized upon impact," Claeys noted in the UBC statement. The object was traveling at about 64,000 km/h when it struck Earth; at that speed, it left behind vapor rather than a crater containing the rock itself.

Perhaps the most unsettling part is the sheer improbability of it all. Of all the rocks orbiting the solar system, the dinosaurs happened to be hit by one of the rarest in the catalog.

"Being impacted by such a rare, distant projectile really underscores how unlucky the dinosaurs were," Claeys said in the UBC statement.

Sixty-six million years later, humans have finally figured out just how much bad luck truly befell our Earth brethren long, long ago.