A new study suggests that predatory dinosaurs, such as Tyrannosaurus rex, do not have permanently exposed teeth as depicted in movies like ‘Jurassic Park,’ but instead they had scaly lips, similar to those of lizards, that covered and sealed their mouths, as published by researchers in the journal ‘Science’.
Researchers and artists have debated whether theropod dinosaurs, the group of bipedal dinosaurs that includes carnivores and top predators such as T. rex and Velociraptor, as well as birds, have lipless mouths where perpetually visible upper teeth hung above their lower jaws. , similar to the mouth of a crocodile.
However, an international team of researchers is now questioning some of the best-known representations and stating that these dinosaurs have lizard-like lips and those of their relative, the tuatara — a rare reptile found only in New Zealand —-, who are the last survivors of an order of reptiles that thrived in the age of the dinosaurs.
In the most detailed study to date on this topic, researchers examine tooth structure, wear patterns, and jaw morphology of the groups of lipped and non-labiated reptiles and fascination that the anatomy and functionality of the theropod mouth is more similar to that of lizards than to that of crocodiles. This involves mouth tissues similar to those of lizards.including the scaly lips that cover their teeth.
These lips were probably not muscular, as in mammals.. Most reptile lips cover their teeth, but they cannot move independently: they cannot bend back in a growl or perform other movements that we associate with human or other mammalian lips.
Study co-author Derek Larson, Director of Collections and Research Paleontology at the Royal Museum of British Columbia, Canada, notes that «paleontologists like to compare extinct animals with their closest living relatives, but in the case of dinosaurs , their closest relatives have been evolutionarily distinct for hundreds of millions of years, and today they are highly specialized.»
«It’s amazing how similar theropod teeth are to those of monitor lizards,» he continues. From the smallest dwarf monitor to the Komodo dragon, teeth work in much the same way. Thus, monitors can compare very favorably with extinct animals such as theropod dinosaurs, extremely in this similarity of functions, although they are not strictly related.»
Co-author Dr Mark Witton, from the University of Portsmouth, UK, comments: «Dinosaur artists have come and gone about lips since we started restoring dinosaurs in the 19th century, but lipless dinosaurs became most prominent in the 1980s and 1990s. Then they became deeply entrenched in popular culture through movies and documentaries: ‘Jurassic Park’ and its sequels, ‘Walking with Dinosaurs,’ and so on.»
«Interestingly, there was never a specific study or discovery that instigated this change, and to a large extent, it likely reflected a preference for a new, fierce-looking aesthetic rather than a change in scientific thinking,» he says. «We are changing this popular representation covering his teeth with lizard lips. This means that many of our favorite depictions of dinosaurs are incorrect, including the iconic T. rex from ‘Jurassic Park.'»
The results demonstrated that tooth wear in lipless animals was certainly different from that observed in carnivorous dinosaurs and that dinosaur teeth were no larger, relative to skull size, than those of modern lizards, implying that they were not too large to cover with lips.
In addition, the distribution of the small openings around the jaws, which supply nerves and blood to the gums and tissues surrounding the mouth, was more lizard-like in dinosaurs than crocodiles. Modeling of the mouth closure of the jaws of lipless theropods showed that the lower jaw had to crush the supporting bones of the jaw or disarticulate the jaw joint to seal the mouth.
«As any dentist will tell you, saliva is important for maintaining healthy teeth. Teeth not covered by the lips are at risk of drying out and may suffer further damage during feeding or fighting, as we see in crocodiles, but not in dinosaurs,» explains co-author Kirstin Brink, Associate Professor of Paleontology at the University of Manitoba (Canada).
As he points out, «dinosaur teeth have very fine enamel and mammalian teeth have horrible (with a few exceptions). Crocodile enamel is a little more horrible than dinosaur’s, but not as bad as that of dinosaurs.» mammals. There are some groups of mammals that do have exposed enamel, but their enamel is modified to withstand exposure.»
For his part, Thomas Cullen, Assistant Professor of Paleobiology at Auburn University (United States) and lead author of the study, says that, «although it has been argued in the past that the teeth of predatory dinosaurs may be too large to be covered by the lips, the study shows that their teeth were not, in fact, uncharacteristically large.»
«Even the giant teeth of tyrannosaurs are proportionally similar in size to those of living predatory lizards when compared by skull size, which rejects the idea that her teeth were too big to cover with her lips,» she says.
The results provide new ideas about how we reconstruct the soft tissues and appearance of dinosaurs and other extinct species. This can provide crucial information about how they fed, how it would affect their dental health, and the broader patterns of their evolution and ecology.
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According to Dr Witton, «Some say that we have no idea what dinosaurs look like beyond basic characteristics like the number of fingers and toes. But our study and others like it show that we are getting better and better at understanding many aspects of what dinosaurs looked like.» the dinosaurs».
The researchers note that their study does not claim that any extinct animals had exposed teeth: some, such as saber-toothed carnivorous mammals or marine and flying reptiles with extremely long, interlocking teeth, almost certainly do.