June 20 (UPI) -- Despite animations and illustrations suggesting otherwise, dinosaurs couldn't stick out their tongues.
New research suggests dinosaurs' tongues were fixed to the bottom of their mouths, like the tongues of alligators.
More than question dinosaurs' ability to make funny -- or fearsome -- faces, the new study, published in the journal PLOS One, also suggests an increase in the diversity and mobility of tongues could help explain the origins of flight.
"Tongues are often overlooked," Zhiheng Li, an associate professor at the Chinese Academy of Sciences, said in a news release. "But, they offer key insights into the lifestyles of extinct animals."
When Li and his colleagues at the Chinese Academy of Sciences and the University of Texas compared the hyoid bones of dinosaurs with those of alligators, crocodiles, pterosaurs and modern birds, they found dinosaurs' hyoid bones were most similar to the hyoid bones of alligators and crocodiles.
The bones, which support the tongue muscle, were short and simple, providing the tongue limited mobility.
"In most extinct dinosaurs their tongue bones are very short," said Julia Clarke, professor at Texas' Jackson School of Geosciences. "And in crocodilians with similarly short hyoid bones, the tongue is totally fixed to the floor of the mouth."
Previous research by Clarke showed large dinosaurs likely made either booming bellows or cooing sounds similar to the noises made by ostriches.
As part of the most recent analysis, Li and Clarke found modern birds and pterosaur dinosaurs, the group of dinosaur species most closely related to birds, boasted a wide array of hyoid bone structures. This diversity of tongue bones may be linked to the development of flight, the scientists propose.
Flying, for example, may have introduced new feeding patterns to pterosaurs and early birds, precipitating the adoption of more mobile tongues.
As species developed wings and talons, foregoing dexterity in their hands, their tongues may have helped pick up the slack.
"If you can't use a hand to manipulate prey, the tongue may become much more important to manipulate food," Li said. "That is one of the hypotheses that we put forward."