Scientists identify ‘oddball’ meteorite that wiped out dinosaurs

By Stephen Beech

Dinosaurs were unlucky to be wiped out by an "oddball" meteorite 66 million years ago, say scientists.

Fine debris thrown into the atmosphere by the space rock, rather than chemicals, was most likely responsible for killing off many of Earth's species — including the iconic reptiles, according to new research.

An international research team identified the class of meteorite responsible for the dinosaurs' extinction as a rare carbon monoxide chondrite.

Scientists in Canada, Belgium, France and Austria used advanced nickel isotope analysis of samples to narrow down the composition of the deadly Cretaceous-Paleogene meteorite.

Their findings were published in the journal Science Advances.

They say the Cretaceous-Paleogene impactor was around six miles wide.

It slammed into the Earth's surface at an estimated 40,000 mph forming the massive Chicxulub crater.

The impact zone is buried underneath the Yucatan Peninsula in Mexico.

Philippe Claeys, who worked on the study as a visiting professor at the University of British Columbia in Canada, said: "Carbonaceous chondrites of the Ornans class are definitely not like the typical meteors you find in museum collections.

"It contains much less volatile elements — like carbon, zinc, water and particularly sulfur — than other classes of meteorites we've discovered so far on Earth.

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"It doesn't alter our theory of what caused the extinction event — but it makes it less likely that sulfur contained in the impactor was the smoking gun.

"The fine debris thrown into the atmosphere would have the primary factor."

Researchers in France conducted high-precision nickel isotope measurements of samples collected over years from a thin layer of clay created across the globe by the impact.

Claeys, a professor with Vrije Universiteit Brussel in Belgium, said: "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."

But he said many questions remain about the origins of the world-altering meteorite.

Potential sources include distant, debris-rich regions of the outer solar system or even the outer area of the asteroid belt near Jupiter.

Carbonaceous chondrites make up only 5% of meteorites so far sampled on Earth.

Carbonaceous chondrites of the Ornans class — CO chondrites — make up a tiny fraction of that group.

Claeys says they are some of the most primitive and untouched materials in the solar system.

He added: "Being impacted by such a rare, distant projectile really underscores how unlucky the dinosaurs were."