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Fossil Site reveals a day when the meteor struck Earth and perhaps even extinguished the dinosaurs

Sixty-six million years ago, a huge meteorite was hit in the earth off the coast of what is now Mexico. Firestorms have burned the landscape for miles. Even animals thousands of miles away were doomed to fail on that fateful day, if not by fire and brimstone, then by mega earthquakes and waves of unimaginable magnitude.

Now scientists have discovered a remarkable fossil pit that seems to date to the day of impact. The burial site consists of more than three meters of sediment and organic remains, which were dumped in North Dakota almost instantly and converted into rock over the eons. It is evident that captures in unprecedented detail the impact of the vast demolition rock that has cleared the path for the evolution of mammals, including the primates known to humans.

In an article made available to reporters on Friday in Proceedings of the National Academy of Sciences, a leading science journal, an international team of 12 scientists described an excavation near Bowman, ND, which witnessed the rapid death of one encapsulated in the old lake and its inhabitants.

Robert A. DePalma, paleontologist at the Palm Beach Museum of Natural History and doctoral student at the University of Kansas. He secretly mined a fossil mine in North Dakota for years. Credit Robert DePalma / University of Kansas

The mess was quickly buried and exquisitely preserved. The deposit was traversed by tiny clay and glass spheres known as tektites, which were formed into molten rock thrown from the sky by the impact.

In the paper, the researchers argue that the fossil bed immediately captures the Chicxulub impact on life on Earth. It seems to be the best snapshot of this day, promoting the scientific understanding of "the full nature and extent of biotic disorders that have taken place," the authors write.

Lead researcher, Robert A. DePalma, is curator of paleontology at the Palm Beach Museum of Natural History in Florida and a student at the University of Kansas. Thirty-seven years old, he was given access to the rich fossil bed by a rancher in 2012, then secretly mined for years . His efforts are described in an article in The New Yorker, which was put online on Friday.

Little by little, Mr. DePalma shared his findings with top scientists, some of whom have since joined as co-authors. These include Walter Alvarez, a geologist at the University of California, Berkeley, who decades ago pioneered the extinction of dinosaurs as the result of such a cosmic influence.

The paper describes how tektites that rained into the water clog the gills of the fish, which were then killed by water surges. The water could have risen from the Gulf of Mexico through an inland sea that had crossed North America at that time. However, the authors argue for another, more likely explanation: These catastrophic waves from the impact of a 10 or 11 earthquake floated water from distant lakes and seas and their associated river channels.

Basically, water moves like a washing machine, "said Phillip L. Manning, paleontologist at the University of Manchester in England and one of the newspaper's authors. "When this shock wave subsides, what was in that body of water falls off almost immediately."

This content formed the North Dakota deposit he described to Mr. DePalma and her colleagues in their work. [19659022] Mr. DePalma was initially disappointed with what he found, he said. He had hoped the place would reveal rhythmic seasonal changes over the years. Instead, the material had been dumped in a big rise. "My idea of ​​multi-layer pond deposits was outside the window," he said.

In the deposit, the team discovered an old freshwater pond whose inhabitants had been quickly cemented by sediment and debris waves. The fossils include sturgeon and 1945 meter long paddle fish, whose scales are intact, but their bodies were torn and smashed. marine molluscs; Leaves and tree fronds and the burned tree trunks. The fish carcasses were not bloated, dilapidated or flushed, suggesting that they were quickly buried – and that there were few animals left to dig after the disaster.

The fossil deposit also teems with tectites, tiny glass beads treacherous effects of the planetary plane impacts. Fifty percent of the fossilized fish were found with tektites in their gills, as if the fish had inhaled the material. Also found were tektites caught in amber. Its chemical composition was unchanged in 66 million years and corresponded to the unique chemical signature of other tektites associated with the Chicxulub event.

The top layer of the fossil bed was rich in iridium, a rare metal that Dr Alvarez had originally discovered in other places to be from the huge object that struck the earth. Iridium, a precious metal belonging to the group of platinum groups, is more abundant in meteorites than in earth rocks.

"Just the idea that fish with impact particles stuck in their gills 66 million years ago and trees with amber strike particles is so extraordinary that you're sure to make a double take," said Matthew Lamanna, a vertebrate paleontologist Carnegie Museum of Natural History in Pittsburgh, which was not involved in the research. "With the reservation that what they are trying to show is really hard to show, I think they did a great job."

The effects of Chicxulub and the global catastrophe that has arisen are sometimes thought of as the killing blow to the dinosaurs. However, many scientists argue that a number of other factors, including volcanic eruptions and climatic disturbances, have contributed to the demise of the giant reptiles.

The article in The New Yorker describes information about the site, which goes far beyond what is found in the scientific paper. Mr. DePalma is quoted as saying that he also found the remains of many dinosaurs in the deposit, suggesting that the North Dakota site may be the first to unequivocally associate the cosmic stroke with the end of the dinosaur age.

Mr. DePalma found "broken teeth and bones from almost every dinosaur group," including the remains of boys, according to the article written by Douglas Preston. A dinosaur egg contained an embryo and other remains, suggesting that dinosaurs and large reptiles are unlikely to die out on this fateful day. "

In an interview, Steve Brusatte, a paleontologist and evolutionary biologist at the University of Edinburgh, called The New Yorker, cites the fossil record, "a remarkable story" he wanted to believe. "But it's disappointing that the dinosaurs are not mentioned in the peer-reviewed newspaper," he said. "And because this is not the case, there is simply no evidence that I can gauge."

Dr. Brusatte said for the time being, "I have more questions than answers when it comes to the dinosaur aspect of history. "

Mr. DePalma said the purpose of this first paper was to determine the geology and timing of events on this catastrophic day. Subsequent articles will go into more detail about the inhabitants, including the dinosaurs that have died. He said, "It was not an article about dinosaurs. This was a basic overview of the site and how it came about. "

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