Dinosaur extinction caused by 6-mile-wide asteroid that came from beyond Jupiter

A large asteroid struck Earth 66 million years ago, killing the giant dinosaurs and countless other ancient creatures.

This cataclysmic event left behind the infamous Chicxulub crater, which is buried underneath the Yucatán Peninsula in Mexico.

It was long debated as to where the asteroid originated. But now, scientists have finally uncovered the identity of the cosmic killer.

The suspected 6-mile-wide (10-kilometer) asteroid was a rare carbonaceous asteroid with its origin traced to deep space region “beyond Jupiter.”

“The findings help resolve long-standing debates about the nature of Chicxulub impactor, reshaping our understanding of Earth’s history and the extraterrestrial rocks that have collided with it,” an international team of researchers stated in the press release.

Long-standing debate about asteroid origin

The asteroid impact occurred at the boundary between the Cretaceous and Paleogene eras (K-Pg boundary).

Decades of studies have strongly shown that this asteroid was the culprit for the dinosaur extinction.

Researchers particularly examine the K-Pg boundary layers to find evidence of this asteroid impact.

The K-Pg boundary layer is a thin layer of sediment found worldwide in marine and terrestrial rocks.

Previous studies have found the presence of elevated levels of platinum-group elements (PGEs), including iridium, ruthenium, rhodium, platinum, and osmium in K-Pg boundary layers. These elements are rare on Earth, but abundant in meteorites. Moreover, these elements are found worldwide, indicating a global impact event.

Despite extensive research, scientists had limited understanding of the Chicxulub impactor’s makeup and where it came from.

This new study sought to find some clues.

They looked for ruthenium (Ru)—a rare element with distinct isotopic signatures—in samples collected from the K-Pg boundary.

“For comparison, they also analyzed samples from five other asteroid impacts from the last 541 million years, samples from ancient Archaean-age (3.5 – 3.2 billion-years-old) impact-related spherule layers, and samples from two carbonaceous meteorites,” the press release noted.

Interestingly, the ruthenium isotopes in the K-Pg boundary closely matched those found in carbonaceous chondrites – a type of asteroid originating from the outer solar system, beyond Jupiter.

C-type asteroid

The researchers found that “the Chicxulub impactor likely came from a C-type asteroid that formed in the outer Solar System.” C-type asteroids are said to be rich in water and organic compounds.

Chicxulub Crater is one of the largest known impact craters on Earth — with a diameter of over 180 kilometers.

The Chicxulub crater is invisible to the naked eye as it is Hidden beneath a thick layer of sediment.

While conducting a magnetic survey in the Caribbean in 1978, oil company geologists stumbled upon a circular arc buried under the seabed of the Yucatán Peninsula. Further investigation uncovered that the arc was actually a portion of a massive, underground crater.

The asteroid killed roughly 60% of the planet’s species. It triggered various immediate and long-term impacts, including higher levels of c arbon dioxide in the atmosphere. It took millions of years for ecosystems to flourish again and biodiversity to recover.

This new study was led by researchers from the University of Cologne and Vrije Universiteit Brussel.

The findings of this new study have been reported in the journal Science.