A new dinosaur with nut-cracking jaws found in the Gobi desert ate like a bird—a parrot, to be exact.
The 3-foot-long (0.9-meter-long) Cretaceous creature had a boxlike skull and beaklike jaw that resemble those of modern parrots, which have beaks that can crack open nuts, a new study found.
The 110-million-year-old skull—as well as "a huge pile" of 50 stomach stones found with the fossil—suggests that the beast was chewing hard, fibrous nuts and seeds, the researchers say. Stomach stones are rocks ingested by some animals to grind food in their digestive systems.
If confirmed, Psittacosaurus gobiensis ("parrot reptile of the Gobi") and its close cousins would be the world's first known nut-eating dinosaur.
Knowing what type of food a dinosaur ate is extremely rare, said study leader Paul Sereno, a paleontologist at the University of Chicago.
"Basically this solves a bit of a riddle for this dinosaur," said Sereno, who is also a National Geographic explorer-in-residence. (The National Geographic Society owns National Geographic News.)
"We've now come closer to why it looks like it does."
The skull, found in the Gobi desert in Mongolia in 2001, once had giant jaw muscles attached to broad sheets of extremely rigid cheekbone, giving the animal a powerful bite, said Sereno, whose study on P. gobiensis appears this week in the journal Proceedings of the Royal Society B.
Like a parrot, the dinosaur was able to move its jaws both vertically and horizontally, allowing it to "shear" tough plants.
Hans-Dieter Sues, a paleontologist at the National Museum of Natural History in Washington, D.C., said scientists have wondered why such dinosaurs and their relatives, called psittacosaurs, had both robust jaws and so many stomach stones.
Usually animals that use stomach stones tend not to need tough beaks. For instance, chickens have puny beaks, relying on sand and gravel in their gizzards to grind down their unchewed food.
Sereno's "very compelling argument that the [new dinosaurs] were eating unusually hard food makes good sense to me," Sues said.
Odd And Successful
Several species of psittacosaurs roamed Central Asia, where their fossils are now plentiful, scientists say.
The creatures often had odd features, such as elaborate horns and porcupine-like tail bristles.
Study leader Sereno said that the psittacosaurs' specialized diet might explain their success during that time.
That's because animals that take advantage of their environments—in this case, eating what few other animals could—have plentiful resources and are therefore more likely to branch into more species, added Sues of the natural history museum.
The new research, he said, "offers a very nice explanation about why these creatures are so diverse."