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Fossils show global catastrophe in the day killed the dinosaurs



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About three-quarters of species were killed in what is called the Cretaceous-Paleogene extinction event is also known as the K-Pg or K-T extinction.

Killer asteroid most known claimed dinosaur. But Tyrannosaurus and Triceratops joined hordes of other living beings. Freshwater and marine creatures were victims, as well as plants and microorganisms, including 93 percent of the plankton. (Lonely branch of dinosaurs, birds, live.)

Battered fish with a weight of deposits in the formation of North Dakota Hell Creek.

Battered fish with a weight of deposits in the formation of North Dakota Hell Creek. credit:Robert DePalma / University of Kansas.

Four decades of asteroid research buttresses the theory of extinction, it is widely perceived as the most plausible explanation for the disappearance of the dinosaurs.

At the end of the 1970s, Luis and Walter Alvarez, the father-son duo scientist at the University of California, Berkeley, studied the unusual geological layer between the Cretaceous and Paleogene periods.

The border was full of element iridium, which is rare in the earth's crust, but not asteroids. Walter Alvarez with a & # 39 is one of the authors of the new study.

Hell Creek fossil represent "the first mass gathering of the death of large organisms, who found", which is on the boundary of K-Pg, study author Robert DePalma said in a statement.

DePalma, a doctoral student at the University of Kansas, began excavating the site in the formation of the Hell Creek in North Dakota in 2013. Since then, DePalma and other paleontologists have found fossilized heaps of sturgeon and paddlefish with glass spheres even in the gills.

They found, squid, animals, called an ammonite, shark teeth and the remains of carnivorous aquatic lizards called mosasaurs.

They found the dead mammals, insects, trees and triceratops. They found a foot-long fossil feathers, traces of dinosaurs and prehistoric mammals burrow. They found a fossilized tree stuff called amber, which captured the glass spheres, too.

The site has "all the signals to a trademark from the impact of Chicxulub,» said Bralower, including glass beads and a lot of iridium.

The geological layer just above the mineral deposit, ferns dominate signs of recovering ecosystem. "It's fascinating," he said.

In the early 1990s, researchers have located the scar left by an asteroid – a crater on the Yucatan Peninsula.

Recommended "kill" the mechanisms for the impact of Chicxulub a lot: it can poison the planet with heavy metals, the ocean turned to acid, shrouded in the darkness of the earth or global firestorms ignited. Its impact can be caused by volcanoes that erupted as the whipping cans of soda.

Hell Creek is more than 3200 kilometers from the Chicxulub crater. But the hail of glass beads, called tektites, rain there within 15 minutes of exposure, said study author Ian Smith, a paleontologist at the University of Vriogo in Amsterdam, which was also one of the first discoverer of iridium on the border K-Pg.

Fish, pressed into the mud, like flowers in a diary, it is remarkably well preserved. "This is the equivalent of human presence in vital positions of buried under the ashes after Pompey," said Bralower.

At the time of the dinosaurs, the site was the Hell Creek Valley. The river is fed into an inland sea, connecting the Arctic Ocean to the Gulf of Mexico prehistoric. After the asteroid hit, the seismic waves from an earthquake of magnitude 10 to 11, swept this sea, according to the authors of the study.

This caused Sun tsunami, but what is known as seiche waves slosh back and forth sometimes seen in miniature in the bath. These may be symptoms of very distant bursts – such as seiche waves that churned in the Norwegian fjords in 2011 after a giant earthquake near Japan's northeast.

Seiche wave from the inland sea is 10 meters, drowning the river valley in the pulse of water, gravel and sand.

Rain of stones and glass followed. The tektites dripping "small funnel in the sediment, set seiche," Smith said, "but you know what they are going down, when the waves are still working upstream."

Smit said that the traces – one of the hadrosaur herbivorous and others with a carnivore, Tyrannosaurus rex may be small – a "significant evidence that the dinosaurs were alive and well at the moment of impact … They are running around, chasing each other" when they were inundated.

This retention, in other words, a fresh hell.

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