Flying is really hard work. Compared to walking, swimming, or running, flying is the form of movement that takes the most energy and requires the most calories. That means that birds have had to evolve specialized ways to be really efficient at finding and digesting their food. A new study of the oldest known bird, Archaeopteryx, shows that some of birds' weirdest mouth features—like extra tongue bones, a sensitive beak-tip, and fleshy "teeth" on the roofs of their mouths—date all the way back to the Jurassic Period. These features, which are still present in most living birds, hint that being extra-good at finding, grabbing, and processing food might be key to a life on the wing.
All birds are dinosaurs, but not all dinosaurs are birds; the birds alive today are the only group of dinosaurs that survived the mass extinction 66 million years ago. Archaeopteryx, which lived about 150 million years ago in what's now Germany, is the earliest known dinosaur that also qualifies as a bird.
But Archaeopteryx lived alongside other small, feathered dinosaurs that, while related to birds, were not birds and were not capable of flight. Telling the two groups apart can be very difficult for paleontologists. "For a long time, there have been very few things that we could say really characterize the transition from terrestrial dinosaurs to flying bird dinosaurs," says Jingmai O'Connor, an associate curator of fossil reptiles at the Field Museum in Chicago and lead author of a study in the journal The Innovation. "These weird little features in the mouth of Archaeopteryx, that are also found in living birds, are giving us new criteria that we can use to tell whether a dinosaur fossil is a bird or not."
The new paper, featured on the cover of the latest issue of The Innovation on February 2, 2026, is based on the latest Archaeopteryx to join the scientific record: the Chicago Archaeopteryx. This fossil has been on display at the Field Museum since 2024 and was first scientifically described in 2025.
When the Archaeopteryx arrived at the Field Museum in 2022, it had not yet been prepared—most of the fossil was still covered by rock. A team of fossil preparators, led by the Field Museum's chief fossil preparator Akiko Shinya, spent over a year painstakingly chipping away at the top layer of limestone to reveal the specimen inside.
"The only reason these structures in Archaeopteryx's mouth were found at all is because our preparators were doing such a meticulous job working on this fossil," says O'Connor.
When soft tissues, like skin and feathers, are preserved in some rocks, they glow under ultraviolet light. "The team used UV light during intermittent stages of fossil prep to make sure that they weren't destroying any soft tissues," says O'Connor. "Plus, some of these soft tissues and bone fragments are really tiny—they're very, very easy to miss unless you're actively looking for them."
During the fossil prep process, Shinya and her fellow preparator Connie Van Beek noticed unusual microscopic features in the bird's skull. "I remember them calling me over and saying, 'Jingmai, we found something strange, come look at it," says O'Connor. "They showed me these tiny, glowing dots, and I had no idea what we were looking at."
She turned to a reference book of bird anatomy, and in the section about mouths, came across an illustration of oral papillae.
"Imagine if the flesh on the roof of your mouth just had rows and rows of tiny, fleshy cones—that's what birds have, and they're called oral papillae," says O'Connor. These fleshy cones look almost like teeth, and they help birds eat—the papillae help guide food down a bird's throat and keep food out of its windpipe.
The team compared the position and appearance of the tissues preserved in Archaeopteryx's mouth to the oral papillae in modern birds, and they determined that the best explanation was that they'd found the first examples of an Archaeopteryx's oral papillae (and first oral papillae in the fossil record).
The researchers found several other features within Archaeopteryx's skull that had never been seen in this species. They spotted a tiny splinter of bone that turned out to be a tongue bone.
Human tongues do not contain bones, but most birds have a set of bones that form the central structure of their tongues. These bones provide additional muscle attachment points, resulting in flexible tongues that help birds use their tongues to reach and manipulate food.
"This teeny-tiny bone is one of the smallest bones in the body, and it indicates that Archaeopteryx had a highly mobile tongue, like many birds today," says O'Connor.
Through CT scanning, the researchers also observed that the tip of the Archaeopteryx's beak contained tiny tunnels: traces of nerves. Many modern birds have what's called a bill-tip organ, a sensitive part at the end of their beaks that can help them root around for food.
Taken together, the evidence of oral papillae, tongue bones, and bill-tip organs in Archaeopteryx suggest that the first birds evolved multiple strategies to help them find and swallow food more efficiently, and that these features go hand-in-hand with their newfound ability to fly.
"These discoveries show this really clear shift in how dinosaurs were feeding when they started flying and had to meet the enormous energetic demands of flight," says O'Connor. "Birds have a super-efficient digestive system—everything is modified to maximize the efficiency of eating and the calories that they can extract from food. And the digestive system starts with the mouth."
