Scientists Discover the First Bird Beak—and It Has Dinosaur Teeth

Updated | How did birds get their beaks? It's hard to imagine modern birds without these pointy appendages, but their origins have long mystified evolutionary scientists.

Now, researchers have discovered that an iconic bird that inspired the likes of Charles Darwin bore the very first beak. The team reconstructed the ancient beaks of Ichthyornis dispar in a study reported in Nature.

Ichthyornis, which lived 100–66 million years ago, plays a key role in the evolutionary journey from dinosaurs to modern-day birds. It's closely related to the birds of today, but still holds on to features like its sharp, curved teeth. Fossilized Ichthyornis remains are a mainstay of museums like the Yale Peabody Museum.

"Right under our noses this whole time was an amazing, transitional bird," said Bhart-Anjan Bhullar, a Yale University paleontologist and principal investigator of the study, in a statement. "It has a modern-looking brain along with a remarkably dinosaurian jaw muscle configuration."

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Researchers used computed tomography (CT) imaging to bring Ichythornis fossils to life. They took very thin images right the way through the bones and stacked them together to make a computer simulation, "like slicing a salami sausage and reassembling it," Kevin Padian, a professor at University of California, Berkeley, explained in a linked comment.

The reconstructions reveal what bird beaks looked like when they first emerged in nature. The beak began as just the tiny tips of Ichythornis' toothy jaw, study author Daniel Field from the University of Bath told Newsweek.

"The first beak was a horn-covered pincer tip at the end of the jaw," Bhullar said. "The remainder of the jaw was filled with teeth. At its origin, the beak was a precision grasping mechanism that served as a surrogate hand as the hands transformed into wings." In other words, its first function was pecking.

"Over time, the portion of the upper jaw devoted to the beak expanded," Field added. "The tooth-bearing jaw elements became much smaller and ultimately lost their teeth."

Ichythornis probably looked a lot like modern seabirds, Michael Hanson, a researcher at Yale and another study author, said in the statement. Its sharp teeth were probably hidden when its mouth was closed under a lip-like tissue, he said.

Much of the bird's skull retained dinosaur-like features, but it probably housed a brain similar to those of modern birds today, the researchers suggest. "A relatively modern brain coexisted with a very dinosaur-like architecture of the skull—far more so than has been previously appreciated," Field explained.

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Bhullar's lab has been investigating this bird for a number of years. "The skull of Ichthyornis even substantiates our molecular finding that the beak and palate are patterned by the same genes," Bhullar said.

The evolutionary journey from dinosaurs to modern-day birds, "the most species-rich group of vertebrates on land," he added, "is one of the most important in all of history."

This article has been updated to include comment from Daniel Field.