About 66 million years ago, the impact of a giant asteroid in the area of what is now Mexico’s Yucatán Peninsula permanently changed the course of evolution. As a result of the catastrophe, more than 75% of all biological species, including the dinosaurs, were literally wiped from the face of the planet. However, a recent study published in Science Advances has prompted the scientific community to reconsider the causes of the global ecological collapse. Based on their findings, the researchers propose that the dinosaurs were destroyed not so much by the impact itself as by the composition of an extremely rare asteroid that triggered a deadly chain reaction.
An international team of scientists conducted a detailed isotopic analysis of nickel in samples from the so-called Cretaceous–Paleogene boundary, or K–Pg boundary. This thin layer of distinctive clay spread across the entire planet after the explosion and remains the principal geological marker of the catastrophe.
The results showed that the Chicxulub asteroid belonged to the CO type, a primitive class of carbonaceous chondrites known as the Ornans group. Such objects account for only about 5% of all known meteorites found on Earth and contain primordial material dating back to the formation of the Solar System. The main feature of this type of rock is its extremely low concentration of volatile elements, including water, carbon, zinc, and sulfur.
Sulfur Is No Longer the Main Suspect
Paleontologists and climatologists previously believed that the enormous quantities of sulfur released when the asteroid vaporized played the central role in causing the prolonged “impact winter.” This gas effectively blocks sunlight, leading to a sharp drop in temperature. However, the new data indicate that a CO-type chondrite may have delivered at least two times less sulfur than previously assumed.
According to planetary scientist Philippe Claeys of the Vrije Universiteit Brussel, the discovery does not disprove the theory that the asteroid impact caused the mass extinction, but it fundamentally changes our understanding of the processes that occurred in the atmosphere. The primary cause of the planet’s global darkening was a massive column of fine silicate dust and fragments of Earth’s crust that were blasted into the atmosphere together with soot from widespread forest fires, blocking sunlight for an extended period.
A Cosmic Coincidence
Scientists still cannot identify the exact birthplace of the Chicxulub asteroid, but its unique chemical profile points to an origin in the distant, debris-rich outer regions of our planetary system. The fact that Earth crossed paths with such a rare and pristine relic of the early Solar System highlights the tragic coincidence that cost the lives of the fauna that existed at the time.
Even 66 million years after the catastrophe, the Chicxulub crater continues to present scientists with new mysteries, demonstrating that the history of the greatest mass extinction on our planet still conceals many secrets.
Earlier, we reported that the killer asteroid struck Earth at its most vulnerable point.
According to gizmodo.com
