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An impact of asteroids near the present Yucatan Peninsula has caused giant waves in an inland sea that have sunk into the mouth of a river, leaving a fossilized record of the day when dinosaurs were swept from the planet.
(Illustration provided by Robert DePalma via UC Berkley)
- A site in North Dakota nicknamed Tanis has perfectly preserved fossils of fish, animals and plants.
- The fossil layer formed when a killer asteroid removed what is now the Yucatan Peninsula.
- Some of the fossilized fish on the site inhaled tiny glass beads formed by the impact.
Buried for 66 million years, a prehistoric cemetery reveals what happened in the minutes following the influx of a giant asteroid into the Earth and the destruction of dinosaurs, according to a new study.
The site, part of the Hell Creek Formation in present-day North Dakota, skirted an inland sea dividing North America into two landmasses.
"What we have here is the geological equivalent of high-speed film right from the first moments after impact.Paleontologist Robert DePalma, lead author of the study, told National Geographic.
Fossils of fish, animals and plants perfectly preserved on the site, nicknamed Tanis, offer a detailed record of what happened immediately after the passage of the killer asteroid off the Yucatan Peninsula, Mexico, according to a study published Monday in the Proceedings of the National Academy of Sciences. The impact created a giant crater, called Chicxulub, and he rejected tons and tons of rock dust and asteroid dust in the atmosphere. The cloud that enveloped the planet resulted in the extinction of 75% of life on Earth and the late Cretaceous.
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"We realized that bad things happened right after the impact, but no one found this kind of smoking gun evidence.In a statement David Burnham, co-author of the Biodiversity Institute study at the University of Kansas, said in a statement. "People said," We understand that this blast killed the dinosaurs, but why do not we have corpses everywhere? "Well, now we have corpses, they are not dinosaurs, but I think they will eventually be found."
In the space of 45 minutes to an hour, thousands of tiny glass beads formed by the impact began to rain on the site. Some of these pearls, called tektites, have been inhaled by fish in the inland sea, according to a press release from the University of California at Berkley regarding the study. The tektites would later be stuck in the gills of the fish. Other tektites, coming out of the atmosphere at a speed of 100 to 200 mph, have landed in the mud left by the waves of the Inland Sea. It is thought that others have caused forest fires all over the continent.
The impact of the asteroid also triggered shock waves that caused the slippage of the inland sea like water in a bathtub. The waves washed sturgeons, paddlefish and other sea creatures on a sandbar at the mouth of a river where they stranded.
The fossilized fish piled on top of each other suggest that they were thrown to the ground and died stranded together on a sandbar after the waves retreated from the inland sea.
(Courtesy of Robert DePalma via UC Berkley)
The tektites and other debris from the impact fell for another 10 to 20 minutes. Another great wave emerged from the sea and covered it with sand, gravel and fine sediment.
"A tangled mass of freshwater fish, terrestrial vertebrates, trees, branches, logs, marine ammonites and other marine creatures is found in this layer under the effect of the wave directed inland, "said DePalma, PhD student at the Palm Beach Natural History Museum in Florida.
In addition to fish and marine organisms, DePalma, who has been working for six years at the site near Bowman, North Dakota, has discovered parts of a triceratops, a duck-billed hadrosaur, insects , mammals and bones from a marine reptile called mosasaur, and burned trees and coniferous branches. He also found feathers that might have belonged to a dinosaur, according to a complete article on the discovery in the New Yorker.
They are all in the sedimentary layer called K-T boundary marking the end of the Cretaceous and the beginning of the Tertiary. This is also called the K-Pg limit.
"This is the first assembly of large organisms by mass death that we have found associated with the K-T limit," DePalma said. "In no other section of the KT border on Earth, you will find such a collection including a large number of species representing different ages of organisms and different stages of life, all of which are dead at the same time, the same day."
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Mark Richards, Professor Emeritus of the University of Berkeley and Professor of Earth and Space Sciences at the University of Washington, said: "It's like a late Cretaceous museum in a layer of one and a half meters thick. "
DePalma said, "It's hard not to be choked and passionate about this topic. We examine one-off recordings of one of the most remarkable impact events in Earth's history. No other site has a disc quite like that. And this particular event is directly related to all of us – to all the mammals of the Earth, in fact. Because it's basically where we inherited the planet. Nothing was the same after this impact. It has become a mammalian planet rather than a planet of dinosaurs. "
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