The popular theory that the Mexican craterChicxulub was originated by a hugeasteroidwhich also caused theextinction of the dinosaursand 65% of all species that existed 65 million years ago have just been called into question by new research by American and Swiss scientists. As published by the magazineJournal of the Geological Society, Gerta Keller and her collaborators have found evidence to suggest that the Chicxulub impact took place up to 300,000 years before the Cretaceous-Tertiary boundary, considered until now as a reference to explain the extinction of the dinosaurs.
The crater, discovered in 1978 in the north of the Yucatan Peninsula, measures about 180 kilometers and was caused by the huge impact of an extraterrestrial mass. Analyzing the sediments, the scientists have observed that four to nine meters of sediment were deposited at a rate of between two and three centimeters for every 1,000 years after the crash. Proponents of the Chicxulub impact theory suggest that the crater and the mass extinction appear far apart in the sediment record due to aearthquake or tsunamicaused by the asteroid impact. But according to Keller, “this layer of sediment was not deposited for hours or days due to a tsunami, but over a very long period of time.”
In the research, Keller and his collaborators found that the sediments that separate the two events are characteristic of normal sedimentation, with holes created by the creatures that colonized the ocean, erosion and sediment displacement, with no signs of structural alteration.
In addition, the scientists also found evidence indicating that the Chicxulub collision did not produce the supposed dramatic impact on species diversity. Specifically, at one point on El Peñón, the researchers found 52 species present in the sediments located below the layer of the ring that created the impact, and the 52 species are still present in the layers above the ring. “We discovered thatnot a single species became extinct due to the Chicxulub impact“Keller said.
Keller suggests in his article that it is possible thatDeccan Traps volcanic eruptions in India, were responsible for the extinction, since the immense amounts of dust and gases that were expelled could have blocked the sunlight, causing a considerable greenhouse effect.
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