Asteroid dust remnants have been discovered in the Chicxulub crater. This confirms the most likely theory of the extinction of the dinosaurs.
Since the 1980s, paleontologists have been debating whether a major asteroid collision around 66 million years ago sealed the end of the dinosaur era. But there are always objections to this thesis. Other recent claims that a series of volcanic eruptions were responsible for the extinction.
Now an international group of researchers has found something that should finally prove the asteroid thesis. Scientists from the University of Texas at Austin have been collecting drill samples in the Chicxulub crater in the Gulf of Mexico since 2016. The 200-kilometer crater was discovered in 1991 and is the site of an asteroid impact that was said to have killed the dinosaurs. In the study, published in the journal Science Advances, they reported high concentrations of iridium in the core of the pits.
In 2019, American paleontologists described fossils of plants and fish, the death of which is directly related to the impact in the Gulf of Mexico.
This discovery of this rare element is a hot trail. The founders of the asteroid thesis, Walter Alvarez and his father, Luis Alvarez, discovered in 1980 a layer of limestone containing a high percentage of iridium in the rock, which had formed at the end of the era of the dinosaurs. Iridium is rarely found on Earth, but on some asteroids. They concluded that such a thing must have hit the ground. The blown dust darkened the sun and caused a cold period. Plants died and so did dinosaurs. So much for the – largely simplified – theory that supposedly explains the disappearance of the lizards at the end of the Cretaceous period.
With the discovery of iridium in the impact crater, supporters of the theory now have another strong evidence, after the crater itself was discovered 30 years ago. Even professor of geochemistry and head of studies, Stephen Juderis from Brussels, went so far as to say that “the episode is finally done”. The massive presence of iridium in the Chicxulub crater eliminates any suspicion of a causal relationship between the asteroid impact and the high iridium content of many rocks in this period. There are also other indications: in 2019, American paleontologists described fossils of plants, fish and other animals, the death of which is directly related to the impact in the Gulf of Mexico.
Supporters of the volcano hypothesis argue that the iridium anomaly could also be due to volcanic eruptions. They link the extinction of dinosaurs to the high level of Deccan trap activity in India. Dekkan-Trapp is one of the largest volcanic regions of origin in the world. The theory, however, is very controversial. Among other things, because iridium is in unfamiliar isotopic ratios for volcanoes.
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