GabyNew evidence that the impactor came from beyond Jupiter could help resolve a long-running debate in cosmochemistry.
When an asteroid struck the Gulf of Mexico 66 million years ago, Earth changed forever. The impact triggered a mass extinction that wiped out about 75 percent of species, including all non-avian dinosaurs.
Why this research matters
The results of a new study indicate that the asteroid responsible for this catastrophe probably didn’t come from nearby but from far beyond Jupiter. The study, published in the journal Science, says the evidence could resolve a long-standing debate about this pivotal moment in Earth’s history.
“This is one of those studies that makes you stop and think about the tragedy and the cosmic interconnectedness of everything,” Steven Brusatte, a professor of paleontology at the University of Edinburgh, told BBC Science Focus.
“Back then, 66 million years ago, dinosaurs around the world were going about their business, just like they had for tens of millions of years, when suddenly this asteroid appeared and changed the world forever. But it didn’t actually come out of nowhere; it had an origin, and that origin lies in the distant corners of our Solar System, beyond Jupiter.”
This moment in time, between the Cretaceous and Paleogene periods, is recorded in the chemical composition of rock layers buried beneath Earth’s surface around the world. In geology, this layer of rock is known as the K-Pg boundary. Here, scientists discovered a high concentration of platinum-group elements such as iridium, ruthenium, osmium, rhodium, platinum, and palladium.
These elements are rare on Earth but common in meteorites. Some scientists previously argued that high levels of these elements at the boundary could be caused by widespread volcanic activity. Others suggested the isotopic signature matched that of asteroids.
To resolve the dispute, researchers took samples from the K-Pg boundary. By comparing them with samples from other asteroid impacts, the team found that the levels of ruthenium (Ru) isotopes did not match those characteristic of Earth or of other meteorite types. Instead, they closely resembled the signature of extraterrestrial carbonaceous chondrites — a type of asteroid that forms in the outer Solar System.
“This piece of space debris from such a distant place somehow, against all odds, intersected with Earth and the dinosaurs. It’s such an incredible story, but it really happened,” said Professor Brusatte.
