The era of dinosaurs came to an abrupt end around 66 million years ago when a colossal asteroid collided with the region now known as the Yucatán Peninsula in Mexico. This catastrophic event sparked global wildfires, massive tsunamis, ocean acidification, volcanic eruptions, and earthquakes.
The impact filled the atmosphere with debris, blocking sunlight and leading to global cooling. This environmental shift devastated plant life and initiated a series of food chain collapses.
In a twist of fate, the dinosaurs were particularly unfortunate. A series of coincidental factors contributed to their downfall. Experts suggest that if the asteroid had struck almost any other location on Earth or hit at a different angle, the destruction might not have been as extensive.
Moreover, the timing of the impact, occurring during spring in the Northern Hemisphere, further hampered the recovery of species in that region.
A recent study published in Science Advances adds to the list of misfortunes. The asteroid was an exceedingly rare type of meteorite, possibly originating from the outer Solar System.
Previously identified as a carbonaceous chondrite, a type of meteorite accounting for less than five percent of those landing on Earth, the new research reveals that the dinosaur-extinguishing rock was part of a subgroup called Carbonaceous Ornans (CO) meteorites, which are an even smaller fraction.
Jupiter typically acts as a gravitational barrier, preventing space rocks from entering the inner Solar System. However, occasionally, smaller ones slip through, but allowing a 10-kilometer (6-mile) asteroid to pass is quite a rare occurence.
“Carbonaceous chondrites of the Ornans class are definitely not like the typical meteors you find in museum collections,” says Philippe Claeys, a geologist at Vrije Universiteit Brussel in Belgium. “Being impacted by such a rare, distant projectile really underscores how unlucky the dinosaurs were.”
To uncover the origins of the impactor, researchers conducted extensive forensic analysis, with the entire planet serving as the crime scene.
The Cretaceous-Paleogene (K-Pg) boundary is the geological marker indicating the end of the dinosaur era, easily recognizable by a distinct black line in the rock layers.
Researchers collected samples from this boundary in five locations: one each in Denmark and Spain, and three in Italy. These were matched against samples from 11 different carbonaceous chondrite meteorites from various subgroups.
The team focused on analyzing nickel, an element more abundant in primitive meteorites than in Earth’s crust, with different meteorites having unique nickel isotope signatures.
The nickel was isolated and purified from the samples, and its isotopes were analyzed and compared.
The analysis pointed strongly to the CO group. “This analysis readily excludes most other potential impactor compositions, including carbonaceous Mighei chondrites, currently most favored in the literature,” the researchers write.
Related: When The Dinosaur-Killing Asteroid Hit, This Life-Form Feasted On The Death
Identifying the impactor’s nature provides insights into the events of that fateful day. Sulfur has often been blamed for the disastrous aftermath, as vaporized sulfur in the atmosphere blocked sunlight and fell as acid rain, contaminating soil and water for millennia.
However, identifying the impactor as this specific meteorite type suggests sulfur wasn’t the primary culprit. “A CO contains much less volatile elements – like carbon, zinc, water, and particularly sulfur – than other classes of meteorites we’ve discovered so far on Earth. 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,” says Claeys.
“The fine debris thrown into the atmosphere would have been the primary factor.”
This discovery highlights the importance of monitoring potential threats from space.
The research was published in the journal Science Advances.
This article was fact-checked by Rachel Garner and edited by Rebecca Dyer. While we pride ourselves on our process, we are only human. If you spot a mistake, please let us know.
