T-Rex With Lips: Yay or Nay?

Although it is true that no living archosaurs have lips, that doesn't necessarily mean that T rex and other theropods didn't. The thing about Phylogenetic Bracketing is that it's an inference based on observations of characteristics seen in close relatives of a given animal. And although it is extremely useful in most situations, it's not 100% on the dot. The key being that "animal X had the same characteristic as animal Y until shown to be otherwise". That's not to say it's not a valid point of discussion. Quite the contrary, it actually has something to do with my next point.

Just because present day archosaurs didn't have lips covering their teeth, that doesn't mean ancient ones didn't. So, are there any other animals of this group that have evidence of lips? Not directly, but I may have a possible example. Sauropods. As we all know, Sauropods and Theropods make up the group Saurischia, or the Lizard Hipped Dinosaurs. So it would make, at least a little, sense to propose similar characteristics between the two. If we look at the skull of Apatosaurus, for example, we can see that we have the two best indicators of lips. Forinuma, or openings for tendons and blood vessles, and a mostly smooth area of the bone around the teeth where the muscles would be located to control the lips. Now, if we look at other skulls from other sauropods, they lack the larger forinuma, but have the smooth area of bone. Much like this camarasaurus. But a Chimpanzee has a similar configuration, but it still has the large, expressive lips. Now their is a caveat to this later on, but I'll bring it up where applicable.

The area of bone around the teeth of T-rex is loaded with lots of forinuma, as can be seen here. This became a point of contention, because it creates a porous surface that would not be applicable to muscular lips. But the thing with me is that when looking at the skulls of Monitor Lizards, I still see a larger than average amount of forinuma. Similarly with this Gecko Skull. Now it would make sense that, if T rex had lizard like lips, he would have more forinuma in his skull, because he was a larger animal than either monitors or geckos. But remember that caveat I mentioned earlier? If it makes sense for T rex to have more forinuma, why not certain sauropods like Camarasaurus? One, although not by much, the skull of camarasaurus was smaller than T rex's. Two, if camarasaurus had lips, they'd be more analogous to say a giraffe or a chimpanzee even. Their lips would make it easier to browse in the tree tops, and as a result would benefit from a similar skull anatomy. Then there is the fact that their is a curious phenomenah of Lizards having more visible forinuma than mammals in general. This may have had more to do with the way their lips are designed, and how they are used.

Conclusion:
Direct evidence that theropod dinosaurs had lips is not currently known to the scientific community. However, there is no direct evidence of a lack of lips, either. But just for me personally, based on what I can see in the anatomy of the skulls, the possibility that this could have been a foundation point where beaks could have evolved from in birds, and would there by be seen in basal coelurosaurs like T rex, and based on current input other scientists, I am still of the opinion that T rex, and possibly other theropods did have lips. But even so, I can say now that my piece is still inacurate. Here's why.

My new theory is that the lips of T rex would not be very dextrous, or muscular. Instead, they'd be more limited in their movement, and would be much shorter on the face than seen in the image. When T rex opens his mouth, both sets of teeth would be well exposed, because the lips are high on the tooth line, not even covering half of the tooth. but when he closes his jaws, the teeth on the lower jaw, obviosly, become covered up by the top set, as they are hidden behind them, and the top set become enveloped by both the top and the bottom lips, because the bottom lips stick out away from the jaw slightly. In the image I drew, most of the top set of teeth are covered by the top lip.

Now just for the sake of disclosure, I'm not a scientist. I'm not a science major. I'm not even interested in a carreer in Paleontology. i'm an artist who works in the service of these professions. My works are a combination of what the scientists say, and what I can fill in when evidence is absent. If new evidence comes to light to conclude that theropods did not have lips covering their teeth, than I not hesitate to change my stance. But until then, I think I gave a good enough case to keep doing what I've already been doing.

This exercise was extremely helpful to me. It reminded me of how much one can learn on their own if they are committed enough to find the truth. I wanna thank those who gave me the feedback, also. I didn't write this piece to attack or discredit you. I just wanted to give my take on the matter. All comments, and other forms of feedback are welcome on my various online profiles so long as your not afraid of having your ideas challenged, and you are willing to have an intellectual conversation either with me or other commentators.

Good luck with your future endeavours, I need to do something fun. Sources are linked below.
Best of luck
~Alex
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Sources:
www.natureworldnews.com/articl…
a-dinosaur-a-day.com/post/1291…
Theropod lips? I don't think so!Theropod dinosaurs have often been given lizard-like labial glands covered with skin, colloquially called "lips". This is based on the presence of little foramina--holes in the skull that provide nutrients, paths for blood vessels and attachment for muscles and tendons. These little holes, the foramina, dot the edges of the lower part of the maxilla and premaxilla in both theropods and in lizards. The interesting thing, is that such foramina are also present in crocodiles and in birds, both of which do not have any type of flexible "lips". So here is a photo gallery of such animals:
First, the Lizards:
Iguana iguana
Dracaena guianensis
Varanus salvator
Varanus salvadorii
Cyclura cornuta
Next, the Theropods:
Daspletosaurus sp.
Velociraptor sp.
Tyrannosaurus rex - "Samson"
Tyrannosaurus sp. "Jane"
The birds:
Cathartes aura
Tachyeres brachypterus
Eudromia elegans
Procellaria

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