sSuddenly, with fire and from above – an impact of ten to fifteen kilometers asteroids 66 million years ago, all popular notions of the end of the world came true. Indeed, between 57 and 83 percent of all animal species on land and at sea suddenly disappeared from the scene at the time — including all but the ancestors of birds, of all dinosaur groups. “KT event” is not only chalky (K) separates from the Third Age (T), but also ended the Mesozoic and entered the Cenozoic Era, and was accompanied by the fifth major extinction since the appearance of the first animals 541 million years ago. As much as the KT event is a prerequisite for the rise of mammals, it is also the most important from our human perspective.
Whether the effect and its consequences alone are responsible, or the long-term effects volcanic eruptions In India, it has long been the subject of sometimes heated debate, which also owes to a stark data problem: sufficient fossil-bearing deposits from the last section of the Cretaceous, Maastrichian, are exceptionally rare.
Kill fish in glass rain
Now, however, two research groups have succeeded in making a statement about the season in which the disaster struck the biosphere. This was made possible by a layer of sediment that American paleontologist Robert De Palma, cousin of film director Brian De Palma, now researching in Manchester, UK, encountered in 2012 in western North Dakota. He dubbed the site “Tanis” and put it in one spot with some of the leading experts on the KT . event 2019 publication published Geologist. Accordingly, the filing date is precisely from the time of the disaster.
The Tanis deposits contain large amounts of fossils of freshwater fish, sturgeon, and paddlefish, among other things, all seeming to have been swept by a powerful wave over what geologists call a sliding slope, an area of land enclosed by a curve. of a meandering river. The fish died there while glass was still raining from the sky: solid droplets of molten rock, called tektite, which were thrown into space by an asteroid impact 3,000 km to the south. Since it only takes about fifteen to thirty minutes for this phlegm to return to land, the fish must have already died on the same day and hour that marked the Mesozoic Era. dinosaur I finish.
But the tanis has more information, thanks in part to its skeleton, which fluctuates with the rhythm of the seasons. pre-existing Posted December 2021 Robert de Palma with other researchers from England and the USA in Scientific Reports Morphological studies and isotopic analyzes of fish bones. Accordingly, the animals must have died together in the northern hemisphere in spring or summer.
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