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Home / Science / Fossil location preserves animals killed within minutes of meteor impact – ScienceDaily

Fossil location preserves animals killed within minutes of meteor impact – ScienceDaily



The beginning of the end began with a violent tremor that caused huge waves in the waters of an inland ocean in today's North Dakota.

Then tiny glass beads fell like bird shots from the sky. The glass rain was so strong that he had set most of the vegetation ashore on land. In the water, fish fought to breathe as the pearls clogged their gills.

The floating sea turned into a 30 meter high water wall as it reached the mouth of a river, throwing hundreds, if not thousands, of freshwater fish – sturgeon and paddle fish – onto a sandbar and temporarily reversing the river's river. The fish were pierced by the water that retreats in the water by glass beads of up to 5 millimeters in diameter, and some of them dug deep into the mud. The torrent of rocks, like fine sand and small glass beads, lasted another 1

0 to 20 minutes before a second large wave flooded the shore and covered the fish with gravel, sand and fine sediment, sealing them from the world for 66 million years.

This unique, fossilized cemetery fish was stacked and mixed with burnt tree trunks, conifer twigs, dead mammals, Mosasaur bones, insects, the partial carcass of a Triceratops marine microorganisms called dinoflagellates and snail-like marine cephalopods called ammonites Paleontologist Robert DePalma has discovered it in the Hell Creek Formation near Bowman, North Dakota, for the past six years. The evidence confirms a suspicion that grumbled at DePalma in his first summer 2013 digging season – that this was a killing field that was laid shortly after the asteroid strike and eventually led to the extinction of all dinosaurs dwelling in the ground. The influence at the end of the Cretaceous, the so-called KT border, has eradicated 75 percent of life on earth.

"This is the first mass murder of large organisms anybody has ever associated with the KT boundary," said DePalma, curator of paleontology at the Palm Beach Museum of Natural History in Florida and a PhD student at the University of Kansas. "At no other KT borderline on earth is there such a collection that consists of a large number of species representing the age of organisms and different stages of life, all dying at the same time on the same day." [19659003] In a newspaper that appeared next week in the journal Proceedings of the National Academy of Sciences he and his American and European counterparts, including two geological scientists from the University of California, Berkeley, describe the site , called Tanis. and the evidence that linked it to the asteroid or comet strike off the Mexican Yucatan Peninsula 66 million years ago. This impact created a huge crater called Chicxulub in the seabed that sent vaporized rocks and cubic miles of asteroid dust into the atmosphere. The cloud finally enveloped the earth and prepared the stage for the earth's final mass extinction.

"It's like a museum at the end of the Cretaceous in a five-foot-thick layer," said Mark Richards, a UC Berkeley emeritus professor of Earth and Planetary Sciences, now Provost and Professor of Earth and Space Sciences at the University of Washington ,

Richards and Walter Alvarez, professors at the Graduate School at the University of California, Berkeley, who hypothesized 40 years ago that a comet or comet was present. Asteroid impact caused mass extinctions, demanded DePalma and The Dutch scientist Jan Smit, to inform himself about the rain of glass beads and the tsunami-like waves that burrow and preserve the fish. The pearls, called tectites, formed in the atmosphere of rock that was melted by the impact.

Tsunami Vs. Seiche

Richards and Alvarez noted that the fish could not have been stranded and subsequently buried a typical tsunami, a single wave affecting that previously unknown arm of the Western Interior Seaway no less than 10 to 12 hours after Impact 3,000 kilometers away would have reached if he had not let down before. Their reason: The Tektite had rained within 45 minutes to an hour after the impact and would have created no mud holes, if the seabed had not already been exposed.

Instead, seismic waves probably arrived within 10 minutes of impact. What would have corresponded to a magnitude 10 or 11 earthquake would have been a saght, a standing wave, created in the inland sea that resembles the water Being spilled in a bathtub during an earthquake. Although large earthquakes often cause seep water in confined waters, they are rarely noticed, Richards said. The Tohoku earthquake in Japan in 2011, a magnitude of 9.0, led to six meters high Seiches 30 minutes later in a Norwegian fjord 8,000 kilometers away.

"The seismic waves get a chance to suspend the water within nine to ten minutes of impact, before all the bullets (small bullets) have fallen from the sky," Richards said. "These globules came to the surface and made funnels – you can see the deformed layers of soft mud in the past – and then the debris covered the globules – no one has seen these funnels before."

The Tektites Would Do It According to Alvarez, who estimated his travel time decades ago, he has come from space on a ballistic trajectory that has reached endless speeds between 100 and 200 miles per hour.

"One can imagine being thrown by these glass balls, they could have killed you," Richards said. Many believe that the debris rain was so intense that the energy on the entire American continent, if not in the whole world, kindled forest fires.

"Tsunami from the Chicxulub impact is certainly well documented, but nobody knew how much resembling it would be in an inland sea," DePalma said. "When Mark came on board, he discovered a remarkable artifact – that the incoming seismic waves would have arrived from the point of impact at about the same time as the atmospheric duration of the ejection wave – that was our big break."

At least two giant septs flooded the land at a distance of maybe 20 minutes, leaving the fossils with six feet of sediment. Above this layer is a clay layer that is rich in iridium, a rare metal found on Earth, but often found in asteroids and comets. This layer is known as the KT or K-Pg boundary and marks the end of the Cretaceous and the beginning of the Tertiary Period or Paleogene.

Iridium

In 1979, Alvarez and his father, Nobelist Luis Alvarez of the University of California at Berkeley, first recognized the importance of iridium found in 66 million year old rock strata in the world is. They suggested that a comet or asteroid impact was responsible for iridium at the KT boundary as well as mass extinction.

The impact would have melted the subsoil beneath the ocean floor and pulverized the asteroid, sending dust and molten rock into the stratosphere. Where the wind would have carried them over the planet and extinguished the sun for months, if not years. Debris would have rained down from the sky: not just tectites, but also residual rocks from the continental crust, including the shocked quartz whose crystal structure was deformed by the impact.

The iridium-rich dust of the pulverized meteor would have been the last to fall out of the atmosphere after the impact and cover the chalk.

"When we proposed the impact hypothesis to explain the great extinction, it was based on finding an anomalous concentration of iridium – the fingerprint of an asteroid or comet," said Alvarez. "Since then, the evidence has gradually increased, but it never crossed my mind that we would find such a deathbed."

The main confirmation of the Meteor hypothesis was the discovery of a Caribbean-buried impact crater Chicxulub and off the coast of Yucatan in Mexico, which was precisely the age of extinction. Shocked quartz and glass spheres were also found worldwide in K-Pg layers. The new discovery in Tanis is the first time that the debris produced on impact has been found along with the animals killed immediately after the impact.

"And now we have this wonderful and totally unexpected site that Robert DePalma digs out to the north." Dakota is so rich in detailed information about what has happened as a result of the impact, "said Alvarez," which is very exciting for me and gratifying! "

Tektites

Jan Smit, a retired professor of sedimentary geology at Vrije Universiteit in Amsterdam in the Netherlands, considered a world expert on tektites. Following the impact, DePalma joined forces with the To analyze and date tectites from the Tanis site, many were found in nearly perfect amber embedded condition, which at that time was a pliable jaw distance.

"I went to the site in 2015 and discovered before my eyes (DePalma) a charred tree trunk or tree trunk about four meters long, covered with amber, which acted as a kind of airgel, catching the tektites as they did came down, "said Smit. "It was a big discovery because the resin, the amber, completely covered the tektites, and they are the most unchanged tektites I've seen yet, and not one percent of the change – we dated them and came right out of the KT limit . "

The Tektites in the gills of the fish are also a premiere.

"Paddlefish swim through the water with their mouths open, snatching their gill predators in that net, and then they swallow like a whale shark or a baleen whale," said Smit. "They also caught tektites, which in itself is an amazing fact, which means that the first direct victims of the impact are these accumulations of fish."

Smit also noted that the buried body of a Triceratops and a duckbill hadrosaur proves beyond any doubt that dinosaurs were still alive at the time of the impact.

"We have an amazing array of discoveries that will prove even more valuable in the future," Smit said. "We have fantastic deposits that need to be examined from different angles, and I think we can explain in detail the sequence of the incoming Ejecta of the Chicxulub impact, which we would never have been able to do with all the other deposits in the area Mexico. "

" So far we've gone 40 years until something like this emerged, which may be unique, "said Smit. "So we have to be very careful with this place as we dig it up and learn from it – this is a great gift at the end of my career, Walter sees it the same way."


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