With yet another Jurassic Park movie headed to theatres, it's the perfect time for busybody scientists to shatter our conceptions of how dinosaurs looked and acted. The latest dino truth bomb comes courtesy of a new study published this week in PLOS One. It suggests that most dinosaurs, including the fearsome Tyrannosaurus rex, couldn't stick out their tongues the way many modern reptiles and birds do.
The T-Rex's tongue probably wasn't as long or flexible as it looks here, a new study finds. Photo: James Morgan (Getty Images)
Researchers compared the mouth anatomy of a variety of dinosaur and ancient reptile species to some of their closest living avian and reptilian relatives, including alligators. They specifically mapped out the hyoid bones, which help anchor the tongue to the body, and surrounding muscles of living species through CT scans, then compared them to fossil specimens mostly sourced from China.
Contrary to popular depictions of predatory dinosaurs roaring with tongues held far out or flicking them out snakelike, they found that most of the species they studied had hyoid bones that resembled those of gators, who keep their tongues firmly stuck in place.
"They have been reconstructed the wrong way for a long time," said study author Julia Clarke, a professor at the University of Texas Jackson School of Geosciences, in a statement. "In most extinct dinosaurs, their tongue bones are very short. And in crocodilians with similarly short hyoid bones, the tongue is totally fixed to the floor of the mouth."
Not every extinct animal they looked at had short tongues. Small bird-like dinosaurs and flying reptiles such as pterosaurs had hyoid bones that ranged in shape, mirroring the variety found in living birds today.
Clarke and her team think that these tongues might even reflect an evolutionary adaptation. As the ancestors that became birds switched from having steady hands to less dexterous wings and developed a more diverse diet, they theorise, their tongues became more flexible to compensate.
"If you can't use a hand to manipulate prey, the tongue may become much more important to manipulate food," lead author Zhizheng Li, a former UT researcher and currently an associate professor at the Key Laboratory of Vertebrate Evolution and Human Origins of the Chinese Academy of Sciences, said in a statement. "That is one of the hypotheses that we put forward."
Another group of dinosaurs also had more complicated tongues. Ornithischian dinosaurs, such as the triceratops, had more mobile tongues than the T-Rex. These dinosaurs, unlike the bird-like dinosaurs and carnivores they studied, were four-legged, plant-eating animals who needed to chew their food.
Based on their results, Li and his colleagues hope that scientists can delve further into how and when birds' mouths and throats adapted to the changing world as they evolved over time.