A dinosaur unearthed in Mongolia is exciting paleontologists because its beautiful appearance adds possible evidence to the idea that some dinosaurs live in water.
Natovenator polydontus may be the first non-avian dinosaur known to have a streamlined body similar to that of a modern waterfowl, researchers report Dec. 1 in Communications Biology. Natovenator and other closely related dinosaurs may have been swimmers, the researchers said, challenging the popular belief that all dinosaurs were human.
Natovenator was smaller than a duck and appeared to swim on its feet, said Yuong-Nam Lee, a vertebrate biologist at Seoul National University in South Korea. “We think Natovenator lives in shallow water and eats small fish,” he says.
This is not the first time that researchers think that non-avian dinosaurs had marine life. For years, paleontologists have debated whether spinosaurs were mammals (SN: 3/23/22). In 2017, researchers said that Halszkaraptor – a relative of Natovenator – had waterfowl and reptile-like features, although scientists could not define the shape. In this new study, Lee and his colleagues examined well-preserved skeletons from the Hermiin Tsav Formation fossils in Mongolia, which were found in Late Cretaceous rocks, dating from around 100 to 66 million years ago. Natovenator’s skull, teeth, neck and hands and feet resemble those of Halszkaraptor, the team reports, suggesting that the two men may have had similar lives. In addition, the structure of Natovenator’s ribs suggests that it had a flattened body similar to that of modern seabirds, with rounded and flattened ribs similar to seabirds, the researchers said.
Natovenator’s resemblance to a duck or cormorant is a true example of what is called adaptive evolution, said Thomas Holtz Jr., a vertebrate biologist at the University of Maryland in College Park, who was not involved. in the study. “Similar plans arise because of similar lifestyles.”
It is still unclear how strong the Natovenator swimmer will be. The dinosaur’s legs were short, and its limbs appear to lack the characteristics of loon-like swimmers, Holtz says. But aquatic animals such as mink and some swimmers today have bones that are not specialized for life in water, he says. “So the Natovenator could be somewhere in between in terms of swimming ability, between something like a mink and a loon.”
Pterosaurs May Have Evolved From Small Reptiles
A mysterious beast that was discovered in Scottish sandstone more than a century ago became part of a famous flying family. The tiny Scleromochlus taylori is a close relative of pterosaurs, winged birds that lived alongside dinosaurs, researchers report online Oct. 5 in Nature.
The findings support the idea that pterosaurs – the first vertebrates to master flight – descended from small, fast, two-legged ancestors. The study also provides an answer to a long-standing mystery: what exactly is S. taylori? Davide Foffa, an archaeologist at National Museums Scotland in Edinburgh, said: “Everything comes down to saving this animal.
S taylori is best known from seven individuals preserved in rocks found in 1907, fossils that are difficult to interpret. For one thing, there are no real bones, just the impression of the surrounding rocks; This bone disappears for a long time. Many studies have described and reinterpreted the creatures from these fossils. In these studies in turn they suggested that S. taylori is closely related to dinosaurs, or pterosaurs, or even crocodile ancestors.
What is clear is that the small reptile, which lived about 230 million years ago, had a very serious body mass, Foffa said. At less than 20 centimeters long, “it will fit in the palm of your hand”, but its head is too big for its body. It also has a small neck and long back. But this strict list is not sufficient to identify the closest relatives of creatures; which requires the best details of the skull, color, body size and more.
So Foffa and his colleagues used a non-destructive scanning technique called microcomputer tomography to collect previously unavailable data on the fossils, from the length of its tail to the extent of its leg bones. ‘the color of it. Some of the creatures – such as its large head – resemble pterosaurs. Others, such as the orientation of its lower jaw, are not like pterosaurs at all, the team found. S. taylori has no known adaptations for flying, jumping or living in trees, according to the team. Instead, he was probably a runner.