Cosmic Science

If it looks like a duck, it might have been a dinosaur

It’s long been accepted that birds are essentially modern dinosaurs, but does that mean an ancient dinosaur could have looked and acted like a duck? Paleontologists are pointing to fossils from Mongolia’s Gobi Desert to make that argument.

In a study published by Communications Biology, researchers say that a well-preserved skeleton dated to the Upper Cretaceous period, between 100 million and 66 million years ago, exhibits streamlined features that would have been well-adapted to swimming. Back then, the region that’s now arid desert would have been much more hospitable to ducks and their kin — offering forests, streams and lakes.

The fossilized species was named Natovenator polydontus, a Latinized scientific name meaning “swimming hunter with many teeth.”

“This dinosaur, a carnivorous theropod that walked on two legs, is the first non-avian dinosaur to evolve into a streamlined body and start living in the water,” Yuong-Nam Lee, a vertebrate paleontologist at Seoul National University, told South Korea’s Yonhap News Agency.

Natovenator was about the size of a duck or a cormorant, with an elongated neck and clawed feet. Based on an analysis of the skull and teeth, the rib cage and the forelimbs, Lee and his colleagues surmise that Natovenator lived in shallow water and ate small fish.

“Although the mode of locomotion in water for the Natovenator is unknown … forelimbs probably were the primary source of propulsion,” the researchers write in their study.

Thomas Holtz Jr., a paleontologist at the University of Maryland in College Park who wasn’t involved in the study, told Science News that Natovenator’s resemblance to present-day waterfowl appears to be an example of convergent evolution. “Similar body plans evolve because of similar lifestyles,” Holtz said.

This isn’t the first time paleontologists have mused over whether dinosaurs might have embraced the life aquatic before the emergence of avian waterfowl. The researchers behind the new study note that Natovenator was an evolutionary relative of another waterfowl-like dinosaur known as Halszkaraptor escuilliei, identified in 2017.

That species is thought to have been semi-aquatic, but Lee and his colleagues say it’s harder to argue that Halszkaraptor led an aquatic lifestyle, based on the existing evidence. “Its body shape could not be inferred from the preserved specimen,” they explain in the study.

Some paleontologists have argued that a bigger, badder dinosaur named Spinosaurus might have been fully aquatic. But a team of researchers led by the University of Chicago’s Paul Sereno cast doubt on such claims in a study published this week.

In their study, Sereno and his colleagues say an anatomical reconstruction based on X-ray scans of Spinosaurus fossils suggests that the creatures were semi-aquatic at best.

Nathan Myhrvold, the co-founder and CEO of Bellevue, Wash.-based Intellectual Ventures, is one of the authors of that study — but he said the doubts about Spinosaurus don’t necessarily apply to Natovenator “because the anatomy is so different.”

“One could do similar biomechanical calculations for Natovenator, but that isn’t something we have done yet,” Myhrvold told me in an email. “So I think it is a cool new find. Like any new thing, it will need more confirming studies.”

Myhrvold said the broader topic of dinosaur adaptation to aquatic environments — or the lack thereof — poses interesting questions.

“It’s long been a mystery as to why we don’t see more semi-aquatic adaptation in dinosaurs,” he said. “Spinosaurus and relatives like Baryonyx were the first such, but there was bound to be more.”

In addition to Lee, authors of the study in Communications Biology, titled “A Non-Avian Dinosaur With a Streamlined Body Exhibits Potential Adaptations for Swimming,” include Sungjin Lee, Philip J. Currie, Robin Sissons, Jin-Young Park, Su-Hwan Kim, Rinchen Barsbold and Khishigjav Tsogtbaatar.

By Alan Boyle

Mastermind of Cosmic Log, contributing editor at GeekWire, author of "The Case for Pluto: How a Little Planet Made a Big Difference," president of the Council for the Advancement of Science Writing. Check out "About Alan Boyle" for more fun facts.

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