The asteroid that killed the dinosaurs had a very strange origin

2024-08-17 15:07:00, Kuriozitete CNA

When an asteroid hit the Gulf of Mexico 66 million years ago, the Earth was changed forever. The impact caused a mass extinction event, killing about 60 percent of the planet's species, including all non-avian dinosaurs.

Now, new evidence suggests that the asteroid after the crash didn't come from nearby, but from far away: beyond the outer reaches of the Solar System, in fact.

The authors of the research, published in the journal Science, say that this evidence finally settles long-standing debates about this crucial part of the planet's history. "This is one of those studies that makes you stop in your tracks and think about the cosmic interconnectedness of everything," paleontologist Prof Stephen Brusatte, who was not involved, explained to BBC Science Focus.

"It's amazing that one day, 66 million years ago, dinosaurs around the world were going about their business as they had been for tens of millions of years, and then suddenly this asteroid arrives out of nowhere and changes the world forever.

But it didn't come from nowhere, it had an origin, and that origin was in the far reaches of our Solar System, beyond Jupiter.

This moment in time, between the Cretaceous and Paleogene eras, is captured in the chemistry of rock layers buried beneath the Earth's surface, all over the world.

In geology, this layer of rock is known as the K-Pg boundary. Here, scientists have previously found high levels of platinum group elements (including iridium, ruthenium, osmium, rhodium, platinum and palladium).

These elements are rare on Earth but common in meteorites. However, some scientists have previously thought that the high levels of these elements could have been caused by widespread volcanic activity.

Others thought that the specific composition of the elements, known as the isotopic signature, more closely matched that of the asteroids.

To resolve the debate, the researchers took samples from the K-Pg boundary. By comparing samples from other asteroid impacts, the team found that the levels of ruthenium (Ru) isotopes were not similar to those from Earth or other types of meteorites.

Instead, they closely matched extraterrestrial carbonaceous chondrites: a type of asteroid that forms in the outer solar system.

“To think that this piece of space debris, from such a faraway place, somehow, against the odds, crossed paths with Earth and the dinosaurs. It's such an impossible story, but it actually happened," said Brusatte./ CNA