Dinosaurs and modern alligators – reptiles similar to alligators – have certain anatomical peculiarities that show their kinship. Thus, some studies suggest that the respiratory system of both was similar, especially adapted to thrive in an environment in which the supply of oxygen is limited – when the first dinosaurs lived, the air contained 12% of this gas; today it owns 21% -.
Now, a work published in the journal PLOS ONE maintains that, most likely, the dinosaurs kept their tongues glued to the lower part of the oral cavity, just like the aforementioned alligators. This would give them a remarkably different appearance from what they show in many of the representations in which these animals appear; in them they are often seen with their tongues sticking out of their mouths, extended between the jaws, as many lizards do.
To determine this, a team of researchers from the University of Texas, Austin, and the Chinese Academy of Sciences have compared the hyoid bones – bone pieces located under the tongue – of alligators, several modern birds and different species of pterosaurs and dinosaurs –among them, a Tyrannosaurus rex–, with which all are more or less related.
In this way, they realized that, in the case of dinosaurs and alligators, the aforementioned bones are remarkably similar; They are simple and short structures, on which the tongue is arranged, which does not show great mobility. “These bones were very small in most dinosaurs. In crocodiles – the order in which alligators are included – this characteristic is also observed, and in them the tongue remains fixed on the floor of the mouth ”, points out Julia Clarke, one of the signatories of the essay, from the Department of Sciences Geological from the University of Texas. In a 2016 study, Clarke had already shown that dinosaurs’ vocalizations surely resembled the sounds that crocodiles and ostriches make.
The tongue-flight connection
On the contrary, pterosaurs, birds and dinosaurs most similar to these have a great variety of hyoid bones, which has led researchers to think that this peculiarity could be related in some way to the ability to fly. They recognize that it is an approach that requires more detailed studies, but, for now, they propose that moving through the air entailed a substantial change in the way of eating. Prey could not be manipulated with wings, which could have been offset by the development of a more mobile language.
Likewise, ornithischians, herbivorous dinosaurs, including stegosaurs, ankylosaurs or triceratops, for example, also have more complex hyoid bones. “In the study of extinct animals, languages are often overlooked. However, they often provide us with fundamental clues about their habits, ”says Zhiheng Li, an expert in phylogenetic analysis and vertebrate evolution at the Chinese Academy of Sciences, who has also participated in this initiative.
Reference: Convergent evolution of a mobile bony tongue in flighted dinosaurs and pterosaurs. Zhiheng Li et al. PLOS ONE . DOI: doi.org/10.1371/journal.pone.0198078
Image: Elmion via Wikimedia / CC
