Scientists have found a fossil site in the US that provides a window into the dinosaurs’ “last day” on Earth. A small piece of the asteroid that crashed into Earth 66 million years ago may have been found in amber, a discovery NASA has described as “mind-blowing.” This is one of the astonishing finds at a unique fossil site in the Hell Creek formation in North Dakota (USA) that preserves the remnants of the landmark disaster that ended the age of the dinosaurs. planet.
There are many finds made in this place. Fossils found include fish sucking up debris thrown out during the impact, a turtle stuck in a stick, and a leg that may have belonged to a dinosaur that witnessed the asteroid impact.
The story of these discoveries is revealed in a documentary entitled Dinosaur ApocalypseBroadcast on the PBS program “Nova” with the participation of naturalist Sir David Attenborough and paleontologist Robert DePalma, as reported by CNN.
DePalma, a graduate researcher at the University of Manchester in the United Kingdom and an adjunct professor in the Department of Geosciences at Florida Atlantic University, began working in Tanis, known as the fossil site, in 2012.
An uninhabitable and desolate place. The large dusty plains now contrast sharply with what the site would have looked like during the late Cretaceous. Back then, the American Midwest was a swamp forest.A now-defunct inland sea known as the Western Inner Channel stretched from what is now the Gulf of Mexico to Canada.
Tanis is more than 3,000 kilometers from the Chicxulub impact crater left by the asteroid that hit the coast of Mexico, but early exploration at the site convinces DePalma. There is evidence of what killed the dinosaurs.
This site is home to thousands of well-preserved fish fossils that were buried alive by displaced sediments caused by a large body of water due to the asteroid impact, according to DePalma. rose from the inland sea channel. Unlike tsunamis, which can take hours to reach land, these moving bodies of water seicheIt appeared just after the huge asteroid hit the sea.
Analysis shows that everything happened very quickly. The researcher is confident that the fish died within an hour of the asteroid impact. and not the result of the massive wildfires or nuclear winter that followed in the days and months that followed. This is because impact spheres, which are tiny bits of molten rock blasted from the crater into the air where it crystallizes into a glass-like material, were found embedded in the fish’s gills. Analysis of the fish fossils also revealed that the asteroid struck in the spring.
“Evidence started to pile up and change the story. It was the progression of clues like the Sherlock Holmes investigation,” DePalma said. It gives you a step-by-step look at what happened right after the impact, and you end up with a very rich resource for scientific research.”
Many of the latest discoveries revealed in the documentary have yet to be published in scientific journals.
“Last day of the dinosaurs” site
The surprising thing about the case is that these remains will literally correspond to the day the asteroid fell. Michael Benton, Professor of Vertebrate Paleontology at the University of Bristol, who served as scientific advisor on the documentary, said he and many other paleontologists believe this. The fossil bed found really represents the “last day” of the dinosaurs.
“Some experts said, ‘Well, it could be a day later or a month ago,’ but I think it really documents the day the asteroid hit Mexico,” he told CNN.
Many of the glazed impact spheres that first revealed traces of the asteroid impact to DePalma are preserved as clay as a result of geological processes over millions of years. However, DePalma and her collaborators also found some globules that had fallen into tree resin on the surface of a trunk that fateful day and were preserved in amber.
“In that amber we found basically a series of orbs frozen in time, because like an insect perfectly preserved in amber, when these spheres got into the amber, the water could not reach them. “They never turned into clay and are perfectly preserved,” he said.
“It’s like taking a sample jar, going back in time and taking a sample from the impact site and then saving it for science,” DePalma said.
The researchers managed to find a number of small, unmelted pieces of rock. in glass spheres. Many of these small pieces of rock are calcium-rich and likely come from limestone found under the Yucatan Peninsula, DePalma said.
However, some of these small fragments caught the attention of scientists: “The composition of the two was very different. There were many levels of chromium, nickel, and other elements common only in meteoritic material, and according to our preliminary analysis these fragments were almost certainly of cosmic origin.”
“This example of what a tiny fraction, maybe micrograms, of the colliding asteroid could be, the fact that a record of it will be preserved is mind-blowing,” said Jim Garvin, Goddard chief scientist who studies the impact craters. On Earth and Mars.
Leg of a dead dinosaur on impact day
On the other hand, another discovery featured in the documentary at the Tanis site is an exceptionally preserved dinosaur leg with intact skin.
Few Cretaceous fossils have been found in the tallest rocks in the geological record, and a limb – a ThescelosaurusA tiny plant-eating dinosaur discovered by DePalma and colleagues— could have died on the same day of the asteroid impact. The preservation of soft tissues, such as the skin, indicates that his body did not have time to rot before it was buried in sediment.
“The only two possible hypotheses are that he died in the surf, or that he died just before (asteroid impact), but it was so close in time that it didn’t have time to decay. It’s not something that died years ago and then rebuilt. That doesn’t happen in soft tissue like this.”
Reference article: https://cnnespanol.cnn.com/2022/05/11/asteroid-acabo-dinosaurs-found-fragment-trax/
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