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Argument for ‘river monster’ Spinosaurus, reinforced by new fossil teeth

More than 95 million years ago, a powerful river system roared through what is now the Moroccan Sahara, home to one of the most unusual river monsters known to science, the predatory dinosaur Spinosaurus. The 50-foot-long, seven-ton animal was fully grown and stretched longer than an adult Tyrannosaurus Rex and had an elongated snout resembling a crocodile, bristling with sharp, conical teeth.

Now, paleontologists digging out these ancient sediments have found large quantities of these conical teeth in two places in southeastern Morocco. Teeth from a bone bed Spinosaurus outperforms other dinosaurs by about 1

50 to one. Since these rocks were formed from river sediments, the discovery implies so Spinosaurus lost its teeth in the water much more often than other dinosaurs that lived in the area – further substantiating the case that this animal was a unique water killer.

“With such an abundance of Spinosaurus Teeth, it is very likely that this animal lived in the river rather than on its banks, ”says lead study author Thomas Beevor, a graduate student at the University of Portsmouth, UK, in a press release.

The new study – recently published in the journal Chalk research– builds on previous work and argues this Spinosaurus was an avid swimmer. A 2010 chemical study found preliminary evidence of this Spinosaurus and his relatives spent much of their days in the water, like modern crocodiles or hippos. And studies by a Moroccan Spinosaurus The skeleton, released that year and 2014, found evidence of features seen in other swimming animals, including a paddle-shaped tail that may have helped propel the dinosaur through water. (Read more about Spinosaurus‘s tail and the cutting edge of dinosaur research.)

“When you study the bones, it’s very difficult to understand how these animals actually interact with their ecosystem,” says the paleontologist and Yale Ph.D. Candidate Matteo Fabbri, co-author of the 2014 and 2020 skeletal studies, who was not involved in the new study. “This study is important because it looks at the ecosystem itself.”

Story of a tail

Spinosaurus is one of the most unusual dinosaurs found so far: a predator that was longer than an adult T-rex, with a six-foot sail on his back.

Discovered in Egypt in the 1910s, the first known fossils of the animal were destroyed in a bombing raid during World War II, making it extremely difficult for paleontologists to retrospectively understand the creature’s anatomy.

In the decades since then, paleontologists have found sister species Spinosaurus all over the world including Asia, South America, Europe and other parts of Africa. The animals’ crocodile-like skulls suggest a similar crocodile-like ability to catch fast-moving prey such as fish. Also a sister species to it Spinosaurus The specimen found in 1983 was stored with fish scales in its rib cage – evidence that suggested but did not prove that the predators ate fish along with pterosaurs and smaller dinosaurs.

In the decades since these discoveries, the group of so-called spinosaurs has distinguished itself through their unusual anatomy of “crocodile facial expressions”. But as strange as these spinosaurs are as a group, so mysterious Spinosaurus remains in a class of its own.

In 2014, researchers led by National Geographic Explorer Nizar Ibrahim, a co-author of the new study, announced that a site in Morocco has received a surprisingly complete Spinosaurus Skeleton. The new bones showed that the hind legs were unusually short compared to the front legs, and as with modern hippos and penguins, the walls of the bones were remarkably thick and dense. These adjustments indicated a semi-aquatic lifestyle.

Evidence for the “river monster” this April Spinosaurus rose when Ibrahim’s team announced they had found the first fossilized tail of one Spinosaurus. Unlike the tails of virtually all other related dinosaurs, SpinosaurusThe tail looked like a paddle. Early robot tests suggest this stern structure would have been powered Spinosaurus water more effectively than the tails of related, landlubbing dinosaurs.

Treasury of Teeth

To investigate further SpinosaurusIbrahim and his colleagues combed two locations in southeast Morocco near the village of Tarda in October and November 2019. The rocks there belong to the Kem Kem Formation, a 150-mile-long escarpment that contains rocks that were formed in an ancient river system that flowed 95 to 100 million years ago.

Although researchers working in the Kem-Kem beds keep their fingers crossed to discover complete skeletons, picture-perfect fossils are extremely rare there as the ancient rivers were troubled places. Almost all Kem-Kem fossils are either isolated fragments of bones or teeth that dinosaurs lost and replaced during their lifetime, as crocodiles do today.

Why is now the golden age of paleontology?

With around 50 new species of dinosaurs each year, the field of paleontology is experiencing a golden age of discovery thanks to new technology and access to areas that were once considered inaccessible.

Both sites have also been mined by locals for fossils that they sold to exporters, wholesalers, collectors and researchers, a craft that employs thousands of people in southeastern Morocco.

The first site had been abandoned before the researchers arrived, but it still contained large chunks of sandstone filled with teeth and bones, allowing the researchers to retrieve 926 fossils in 2019. The second location, less than a mile away, was an active mining site? ˅. To obtain a comprehensive sample of the site’s fossils, study co-author David Martill, a paleontologist at the University of Portsmouth, UK, bought 1,261 fossils that an excavator had found there.

The first location contained almost half of all recovered fossil teeth – and a sixth of all fossils at the location – Spinosaurus Teeth. The second place included more than two out of five fossil teeth recovered there Spinosaurus. All in all, Spinosaurus The teeth made up almost a third of the vertebrate fossils in the second site, an extremely unusual find. “We know of no other place where such a mass of dinosaur teeth has been found in bone-bearing rock,” Martill said in a statement.

The second most common “teeth” at the two locations were technically no teeth at all. It was the heavily modified, tooth-like scales that lined the old sawfish’s snout Onchopristis. The teeth of dinosaurs other than Spinosaurus were barely represented.

A powerful swimmer

The researchers recognize an alternative to their ideas about swimming Spinosaurus: Instead of swimming fully, Spinosaurus Perhaps they caught fish at the edges and shoals of the water, like a modern heron, and lost teeth, which then fell into the water. However, the scientists note that waders tend to be disproportionately long Hind legs, while the Moroccans Spinosaurus has been unusually short Ones.

“These proportions of the hind legs not only do not match those of a wading animal, they also suggest it Spinosaurus is less adapted to a wading lifestyle than [nearly] any other theropod that is not a bird, ”the study’s authors write. Instead, they argue that the more solid explanation is this Spinosaurus actively swam in the rivers of the Kem Kem, shedding teeth as he swam and hunted through the water.

More fossils will certainly come from the rocks of Kem Kem – and these teeth are far from the final word on seduction Spinosaurus. But for now, at least, the data agrees with a provocative picture of the distant past: a massive, crocodile-like dinosaur swimming through mighty rivers that now resides the Sahara.

Fabbri says the results of the new study are a welcome treat: more evidence in line with the idea that has been in the works for decades Spinosaurus was a water-dwelling river monster. “Science is constantly correcting itself,” he says. “But it’s also good to have good news that we were right!”

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