A dinosaur unearthed in Mongolia is making a splash amongst paleontologists, as its modern physique provides potential proof to the concept some dinos have been suited to life within the water.
Natovenator polydontus will be the first recognized nonbird dinosaur to have possessed a streamlined physique corresponding to that of recent diving birds, researchers report December 1 in Communications Biology. Natovenator and different carefully associated dinosaurs could have been swimming predators, the researchers say, difficult the favored notion that each one dinos have been landlubbers.
Natovenator was small like a duck and doubtless used its forelimbs when swimming, says Yuong-Nam Lee, a vertebrate paleontologist at Seoul National University in South Korea. “We think that Natovenator lived in shallow water and ate small fish,” he says.
This isn’t the primary time that researchers have suspected a nonbird dinosaur of getting an aquatic life-style. For years, paleontologists have debated whether or not spinosaurs have been aquatic predators (SN: 3/23/22). And in 2017, researchers reported that Halszkaraptor —an in depth relative of Natovenator — had options analogous to these of aquatic birds and reptiles, although the scientists have been unable to deduce a physique form.
In the brand new examine, Lee and colleagues analyzed a well-preserved skeleton from the Hermiin Tsav fossil formation in Mongolia, present in rocks from the Upper Cretaceous, which dates to about 100 million to 66 million years in the past. The cranium, enamel, neck and limbs of Natovenator are akin to these of Halszkaraptor, the workforce reviews, suggesting the 2 in all probability had comparable lives.
What’s extra, the orientation of Natovenator’s ribs signifies that it had a streamlined physique like that of recent waterfowl, with a compressed and flattened rib cage akin to aquatic reptiles, the researchers say.
The shut resemblance between Natovenator and a duck or cormorant is sort of definitely an instance of what’s often known as convergent evolution, says Thomas Holtz Jr., a vertebrate paleontologist on the University of Maryland in College Park, who was not concerned within the examine. “Similar body plans evolve because of similar lifestyles.”
It stays unclear simply how robust a swimmer Natovenator could have been. The dinosaur’s forelimbs seem brief, and its hind limbs appear to lack attributes of kick-propelled swimmers like loons, Holtz says. But semiaquatic mammals like minks and another profitable trendy swimming predators have skeletons that aren’t extremely specialised for all times within the water both, he says. “So Natovenator might be intermediate in swimming ability, between something like a mink and a loon.”
