A new study has found evidence that at least one type of dinosaur may have been skilled swimmers, plunging into the water like a duck to stalk prey.
The study, published in Communications Biology on December 1, describes a newly discovered species, Natovenator polydontus. The theropod, or hollow-bodied dinosaur with three toes and claws on each end, lived in Mongolia during the late Cretaceous period, from 145 to 66 million years ago.
Scientists from Seoul National University, the University of Alberta, and the Mongolian Academy of Sciences collaborated on the research.
The researchers note that nattovenator had contour ribs, like those of diving birds.
“Its body shape suggests that Natuvinator was a swimming predator, and that the streamlined body evolved independently in separate lineages of theropod dinosaurs,” the authors wrote.
The Natovinator specimen resembles Halscaraptor, another dinosaur discovered in Mongolia, and scientists think it was likely semi-aquatic. But the Natovenator specimen is more complete than Halszkaraptor, making it easier for scientists to see its streamlined shape.
The researchers explain that Natovenator and Halszkaraptor used their arms to propel themselves through the water.
David Hone, a paleontologist and professor at Queen Mary University of London, told CNN that it’s hard to pinpoint exactly where Natuvinator is in the spectrum, from terrestrial to completely aquatic. But he said the specimen’s arms “look like they’re really good at moving water.” Hoon participated in a peer-reviewed study on the biology of communication.
In addition, Natovenator had dense bones, which are essential for animals diving below the surface of the water.
As the authors write, it had a “relatively streamlined body”.
The next step, Hoon said, will be to model the dinosaur’s body shape to help scientists understand exactly how it moved. “Does she paddle with her feet, a kind of dog paddle?” How fast can you go? »
Additional research should also focus on the environment in which the Natuvinator lived. The specimen was discovered in the Gobi Desert in Mongolia, but there is evidence that lakes and other bodies of water existed in the desert in the past.
“There is a real question, well, you have a dinosaur swimming in the desert, what is it swimming in?” he said. “Finding the fossil record of these lakes is going to be difficult, but sooner or later we might find one. And when we do, we might find a lot more of these things.”
Nizar Ibrahim, senior lecturer in paleontology at the University of Portsmouth, whose research includes findings suggesting Spinosaurus was semi-aquatic, told CNN he was not yet convinced by the study’s findings. More rigorous quantitative analysis would have made the results more convincing, he said.
“I wanted to see, for example, a really robust description of bone density, of animal bone tissue, in a larger data set,” he said. “Even the anatomy of the ribs, if they kind of put that into a bigger picture — the huge dataset that would have been useful.”
He said the “anatomical evidence is less clear” for swimming than for Spinosaurus.
And like Hone, he’s also curious as to exactly what waters the Natovenator might be swimming in. “The environment in which this animal was found, in Mongolia, is the opposite of what you would expect for a water-loving animal,” he said.
But he hopes the study will help open the door to broader insights into dinosaur behaviour. Dinosaurs were once considered purely terrestrial, but mounting evidence suggests that at least some species spent as much time in the water as they did on land.
“I am sure there will be many, many surprises,” Ibrahim said. “And we will find that not only have dinosaurs been around for a very long time, but they are also, you know, very diverse and very good at conquering a new environment.”