if tyrannosaurus rex When he closed his mouth, his teeth were no longer visible – thin, scaly lips completely covering the teeth. A work group led by Robert Resch of the University of Toronto Mississauga reached this conclusion based on dental examinations and anatomical comparisons of theropods with lizards and their crocodile relatives. Crocodile teeth are clearly visible even when the mouth is closed, and predatory dinosaurs are usually depicted with protruding teeth – lizards, on the other hand, have lips that cover the teeth. The team also now reports in Science.The proportions of the teeth of predatory dinosaurs, despite their often gigantic size, are more similar to those of monitor lizards than to crocodiles. In addition, dinosaur teeth lack the damage that often occurs in crocodiles due to their location outside the mouth.
Thus, the working group clarifies a long-open question related to dinosaur anatomy. This is because soft tissues such as lip flaps are extremely rare in the form of fossils, and no fossilized dino lip has been found to date. In popular, but also scientific representations, it has long seemed clear: even when the mouth is closed, the teeth of the upper jaw can be seen outside the mouth in most images. The new study illustrates this prehistoric increase. Numerous evidence points to the presence of lips in predatory dinosaurs, Reisz’s team writes. For example, the argument often put forward against this thesis is incorrect: the teeth are very large, but compared to the skull, they are no larger than those of the liped monitor lizards – therefore the lips can also protect a bite the size of a banana. dinosaur.
The teeth themselves show that it must be like this, if you don’t have lips, it is very difficult to keep your teeth moist all the time. Tooth enamel contains a small amount of water and can therefore dry out. Even though dry enamel is harder, it’s more sensitive to scratches and abrasions — and without a lip it’s easier for your teeth to bump into something. For this reason, the teeth of crocodiles show significantly more wear externally than internally, while those of predatory dinosaurs do not. This indicates that the soft tissues outside the mouth resemble modern-sized lizards and other quadrupeds more than they do crocodilians or birds, the working group wrote. In future installments of Jurassic Park, however, there likely won’t be a plump Velociraptor: unlike mammals, whose lips are flexible and peppered with sensory cells, dinosaurs probably had some sort of protective tissue in front of their teeth.
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