Excavations at a site called Tanis in North Dakota have yielded astonishing results: Scientists have discovered several impressively well-preserved dinosaur remains, some even with their skin intact.
Paleontologists believe that the inhabitants of Tanis died and were buried the same day 66 million years ago, when a giant asteroid struck the Earth, ending the age of the dinosaurs.
To date, very few dinosaur remains have been found dating back at least a few thousand years before the collision. If scientists are right in their estimates, the findings in Tanis have the rarest value.
The BBC, along with Sir David Attenborough, have been filming a TV show in Tanis for three years, which will air in the UK on April 15, bringing these discoveries to the public for the first time.
Among the finds are fish, the gills of which had stuck small fragments that fell to the ground after a collision, a fossilized turtle pierced by a piece of wood, like a skewer, the remains of small mammals and the remains of burrows in which they lived, an embryo in a feather an egg, even something similar to a fragment of the asteroid itself.
“The many details found at Tanis tell us minute by minute what happened – almost like a movie. The fossils seem to take us back to that day,” said Robert DePalma, a graduate student at the University of Manchester who led the excavation at Tanis.
Most scientists today agree that the most recent mass extinction of species, including dinosaurs, was caused by the planet colliding with an asteroid about 12 kilometers in diameter.
It probably fell into what is now part of the Gulf of Mexico near the Yucatan Peninsula (this place is known as the Chicxulub Crater). Tanis is located almost 3000 km from the crater, but the impact was so strong that its effects were felt all over the planet.
The fossils found in North Dakota are rather chaotic: aquatic organisms mix with terrestrial ones, apparently under the influence of strong waves of river water, which emerge from a strong vibration of the earth’s surface.
The most interesting finds are fish, including a distant relative of modern sturgeon. Small particles stuck in their gills, balls of molten rock, scattered over a huge area as a result of the impact.
Chemical and radiometric analyzes have shown that these pieces of stone are related to the point of impact and two particles recovered from preserved tree resin also contain tiny inclusions that indicate their extraterrestrial origin.
“When we found these inclusions in small fused particles, we did a chemical analysis,” explains Professor Phil Manning of the University of Manchester. “We were able to determine the composition of this material. All the data, all our chemical data. The study strongly shows that these are parts of an asteroid that killed the dinosaurs.”
Tanis’s findings were first reported by the New Yorker in 2019.
Scientific ethics requires that all new data be initially published in peer-reviewed scientific journals. To date, several articles and reviews have been published, but the process of studying the finds at Tanis is not yet complete: paleontologists continue to extract and describe new fossils.
Professor Paul Barrett of the Natural History Museum in London, a specialist in avian (mostly herbivorous) dinosaurs, examined some of the findings.
“He is a Theselosaurus. Until now, we had no idea what his skin was like, which shows very convincingly that these animals were scaly, like lizards. They did not have wings like their modern carnivores,” he says. “It looks like the animal’s leg was just amputated. There are no signs of disease on it, no obvious pathology, no sign that it was gnawed. Obviously, the animal died instantly.”
The question is whether this dinosaur really died on the day of the asteroid impact as a result of the ensuing flood. Tanis’s team believes this is probably the case, given the location of the limb in the sediment.
However, other scientists, notably Professor Steve Brusatt of the University of Edinburgh, remain skeptical.
Professor Brusatte believes that the animals in Tanis died before the impact and the strong ground movement after the meteorite impact brought them to the surface, after which they were covered with a new layer of debris and so there was an illusion that they died immediately after the impact. collision.
“These fish with the particles in their gills are the real calling card of the asteroid. But as for some of the other claims, I would say there is circumstantial evidence, but we do not know everything yet,” he says. Does it really matter if they died the day before or years ago? A pterosaur egg with an embryo inside is very rare; there is nothing like it in North America. You do not have to reduce it all to asteroids. “
Modern X-ray technology allows you to determine the chemical composition and properties of the egg shell. It was probably leathery rather than hard, which may indicate that the female pterosaur buried the egg in the sand like a turtle.
X-ray tomography can also provide virtual 3D images of a pterosaur chick’s bones and reconstruct the skeleton. This way you can imagine what the animal looked like in life and Robert DePalma did just that.
The baby pterosaur was probably a species of the azardaridae family, a group of flying reptiles that lived in late Cretaceous. The wingspan of an adult can reach 10 meters.
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