Asteroid dust helps solve the mystery of dinosaur extinction

More than 99% of all living organisms on Earth are now extinct. Most of them died quietly. However, the history of the Earth has five main The mass Extinction events – known as Big five – During which many species became extinct at the same time.

Each of the five major events caused at least 40% loss of all species on Earth. Yet humans hold a particular grudge against the most recent one, which brought a sudden end to the 160 million-year history of dinosaurs. It was the Cretaceous – Paleogene extinction, and it occurred 66 million years ago, at that time wiping out about 75% of all species on Earth. Except for sea turtles and crocodiles, no four-legged animal larger than 25 kg survived.

After decades of heated debate, scientists have compromised on two major theories about the cause of this extinction. First possibility Effect of an asteroid That created the 180-km-wide Chicxulub impact crater in the modern-day Yucatán Peninsula in Mexico. Second, a series of eruptions in the volcanic region known as Deccan Trap in India.

Last week, an international team of scientists with data from four independent laboratories Published a study Claiming ended the debate. They say that the 12 km wide asteroid was to blame.

A Case Closed?

The study looked at rock samples collected in the pit, which is now underwater. They found a layer of terrestrial soil mixed with “space dust” containing the element iridium, which can be found in high concentrations in meteorites but is rare in the Earth’s crust. This layer was four times thicker in the impact crater than the surrounding area.

The team quickly found a 5-cm layer of sediment beneath the limestone from the Paleogene, a geological period that began shortly after extinction. This thin layer of sediment had an iridium concentration of one part per billion compared to 0.04 parts in the earth’s crust.

A map in the Yucatan Peninsula showing where the Chixkulub crater is.