Scientists Pinpoint the Rare Meteorite That Ended the Dinosaur Era

About 66 million years ago, a colossal space rock slammed into what is now the Yucatán Peninsula, carving a 180‑kilometre crater and kicking off a chain reaction that erased three‑quarters of life on Earth—including the mighty dinosaurs. For decades scientists have known the impactor as the Chicxulub meteor, but they’ve still been guessing what kind of rock it actually was.

Now a multinational consortium led by postdoctoral researcher Georgy V. Makhatadze has taken a big step toward answering that question. By measuring subtle variations in nickel isotopes trapped in the thin clay layer that blankets the globe after the impact, the team was able to compare the signature of the Chicxulub debris with hundreds of meteorite samples collected over the last century.

The result? The data point overwhelmingly toward a carbonaceous, specifically an Ornans‑type (CO) chondrite. Those rocks are among the most primitive relics of the early solar system, making up only about five percent of all meteorites that reach Earth, and the CO subclass is an even tinier slice of that pie.

“CO chondrites are weird, low‑volatility rocks,” explains Dr. Philippe Claeys of the University of British Columbia. “They contain far less carbon, zinc, water and sulfur than the more common meteorites we see in museum displays. That means the sulfur‑rich fumes we once blamed for the mass extinction probably weren’t the main culprit.” Instead, the team argues, it was the massive cloud of fine dust and debris lofted high into the stratosphere that blocked sunlight and triggered the “impact winter” that sealed the fate of the dinosaurs.

To reach this conclusion, the researchers gathered clay samples from impact‑related layers in places as far apart as Mexico, Italy and Japan, and then performed ultra‑precise nickel‑isotope measurements at labs in Brussels, Vancouver and Vienna. By matching the isotope ratios with those of known meteorite groups, they could eliminate most candidates and zero in on the CO chondrite family.

Where did this rare rock come from? The study suggests an origin in the outer reaches of the main asteroid belt, or perhaps even farther out near the Kuiper Belt—regions rich in primitive, carbon‑laden bodies. While the exact orbit remains a mystery, the odds of a CO chondrite hitting Earth are slim, which makes the Chicxulub event all the more extraordinary.

Beyond satisfying a scientific curiosity, the findings have practical implications. Better knowledge of impactor composition can improve modeling of how different rocks behave when they strike the planet, which in turn informs planetary‑defense strategies for any future threats.

Much work still lies ahead—questions about how the impactor broke apart, the precise timing of the fallout, and the broader ecological fallout are still open. Still, this nickel‑isotope detective work has trimmed away a lot of uncertainty, bringing us a step closer to understanding the cosmic crash that ended the age of dinosaurs.