(ORDO NEWS) — Usually carnivorous theropods are depicted with large teeth protruding from their mouths, like those of crocodiles.
However, it seems that in reality they did not look so scary, and their teeth were hidden behind their lips – like those of lizards.
Giant tyrannosaurs are the main “stars” of all books and films about dinosaurs. A series of large protruding teeth gives these predators a particularly frightening appearance.
From the point of view of science, this detail is not so obvious. Unlike bones and teeth, soft tissues are almost never preserved in fossils.
Therefore, discussions about whether tyrannosaurs and other theropods had lips (like modern lizards) or not (like crocodiles) have been going on for decades.
Of course, filmmakers prefer the second option, which is much more spectacular. However, this image may be far from reality.
Tyrannosaurs moved much more slowly than on the screen, and their teeth were covered with soft lips. This conclusion was made by Canadian and American scientists.
Thomas Cullen and colleagues analyzed the relationship between skull and tooth sizes between extinct theropods and their modern reptile relatives such as Komodo dragons.
For both, it turned out to be about the same, and even in tyrannosaurs, the teeth were not too long to protrude noticeably from the mouth.
Next, the scientists examined sections of the teeth of a crocodile and an ancient daspletosaurus.
The thickness of the enamel on the outer, outward-turning side of the crocodile’s teeth turned out to be much thinner than on the inner side.
But the theropods did not have such a noticeable difference, which may indicate the presence of lips that protected their teeth from the external environment.
Finally, paleontologists have studied other details of the skull anatomy of theropods, crocodiles, and lizards.
Crocodiles have many tiny holes on their faces that help them feel pressure. Lizards do not have them, but there are a number of holes located directly above the teeth, through which blood vessels and nerves pass.
From this point of view, theropod skulls also turned out to be closer to lizards (which have lips) than to crocodiles (which do not).
All these data, according to Cullen and his co-authors, testify in favor of the hypothesis that the teeth of tyrannosaurs were closed by lips and did not protrude beyond the mouth.
However, the discussion is far from over. In particular, some data show that the bones on the muzzle of these predators were rough, like those of the same crocodiles.
This means that this part of their body was covered with scales, not skin, and there could not grow an excess of soft tissue necessary for the formation of lips.
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