Dinosaur lips?

[mest]

I just came across this when comparing crocodilians and alligators and their evolution. Modern living dinosaurs as some like to think.
One way to tell the difference is their headshape:

On closed jaws alligators are visible only upper teeth, crocodiles both. Lizads on the other hand hide their teeth when closing jaws.

One thing that had always bothered me is the 1993 "Jurassic Park" T-Rex. It is just so freaky and unnatural looking. Something that can only be born in Hollywood. But it made history - after 1993 everyone knows that T-Rex looked like Hollywood tells us.

For me even this looks a lot more accurate than Spielberg's T-Rex:

When using scull of the extinct predator in 3d software you can get the idea what is fact and what is fiction.

So to get back on the topic, Robert Reisz, a paleontologist University of Toronto suggests that theropods' teeth were not bared all the time, extending outside their mouths and fully visible whether their jaws were open or closed. Their teeth were covered by scaly lips.

http://www.livescience.com/54912-did-t-rex-have-lips.html

I know, many don't like that kind of theories, because everyone in dinotoyblog knows T-Rex always shows his teeth. Actually he never even closes its mouth 

https://www.google.com/search?q=carnivorous+dinosaurs&source=lnms&tbm=isch&sa=X&sqi=2&ved=0ahUKEwjtjKH_xsnTAhULIpoKHXtcACsQ_AUIBigB&biw=1360&bih=619#tbm=isch&q=tyrannosaurus+rex

[Lanthanotus]

[...]

... Actually he never even closes its mouth 

[...]

Emphasis on this one

We recently had quite a debate about the issue in this forum (see here) and I totally am with you in the observation, that theropod lips vanished with JP in 1993. Before, all tehropod depictions that come to my mind showed the animals with lips, often also with closed mouths (), just such likes as dimetrodon etc. wre sometimes depicted with bare teeth. However, I gonna repeat myself, the default trait in vertebrates through all classes seem to be, that animals can close their mouth shut by lips or similar tissue, just a minor part of species of (semi)aquatic animals have bare teeth and only very few terrestrial animals have a set of teeth (never more than two pair) blaying bare, in no case is the whole dentition laying bare.

[Lanthanotus]

PS: In accordance with my scientific view I removed or covered teeth on most of my theropod figures, removed by those with closed mouth (like Safari Coelophysis, Yutryrannus and Schleich Allosaurus,... and covered by those with articulated jaws as can be seen here).

[Cloud the Dinosaur King]

We could look to dinosaurs closest relatives, the birds! Oh wait, they don't have teeth. Curse you evolution!

[WarrenJB]

One thing that had always bothered me is the 1993 "Jurassic Park" T-Rex. It is just so freaky and unnatural looking. Something that can only be born in Hollywood. But it made history - after 1993 everyone knows that T-Rex looked like Hollywood tells us.

The movie toned it down a bit (not much!) but I couldn't take the JP Tyrannosaurus* altogether seriously after learning about the 'angry eyes' design.

*[grumpy sod]It rolls off the tongue so nicely. "Tie-rrrrranosoris." But after '93 and four movies you only ever see 'T-Rex'. Not even T. rex, but T-Rex. Makes it sound like a 50-year-old rock band. Or margarine. [/grumpy sod]

I don't want to reiterate much about lips because as Lanthanotus says, it's been gone over recently. I'll just add that Jaime Headden had quite a bit to say about dinosaur lips too. He doesn't hold a position at the university of Toronto, but still, I found it food for thought.

[Neosodon]

I never really had an opinion on T Rex lips during the last debate but since then I noticed something. And being aquatic isn't what determines if it has lips or not.

Some animals it is quite clear that there is no possible way they could have lips for example Ramphorynchus.


There is just no way it could fit lips over those teeth. T Rex had pretty big teeth too. Although their not quite as extreme as Ramphorynchus's teeth I have a hard time imagining T Rex having lips big enough to cover it's teeth. If it had them they would be so big it may just end up biting them off in a fight.


There are no lipless land animals toady so I can get why a lipless T Rex may seem silly to some people but their are also no land animals today that have the tooth to mouth ratio like that of a T Rex. Well ok there are beavers but those are just its two front teeth and it uses them in a completely different way.

[spinosaurus1]

Tyrannosaurus tooth to skull ratio are actually not too different then varanids at skull length parity.

The photo you posted has all the teeth in the tyrannosaurus mouth hanging out of socket. The roots of the teeth ( the dark area ) should not be visible.

The teeth of tyrannosaurus or theropods in general are no where near as exaggerated as certain toothed pterosaurs. Nor are they arranged on a precumbant fashion.

[BlueKrono]

Oftentimes animals with oversize teeth have sockets in the opposite jaw that they fit into. The modern-day payara, with Smilodon-like teeth, looks like they would have to stick out. However, they fit into sockets in the soft tissue of the upper jaw and aren't revealed unless the fish has its mouth open. In general I think evolution tends toward concealment of natural "weapons of mass destruction", though there are a few exceptions of course.

[WarrenJB]

Ignoring the beak for a minute, if Ramphorynchus was swooping and dabbling for fish for a living, does that count as being constantly hydrated?

Tyrannosaurus tooth to skull ratio are actually not too different then varanids at skull length parity.

Yup! The skulls of monitors and other lizards can be surprising with how toothy they are. In life, even with gaping mouths, the most you can often see are nubs mostly covered with gums. Here's a relevant Tetzoo post from a while ago.
So pushing Tyrannosaurus' teeth back into their sockets and adding a hypothetical thick layer of gum tissue, they could have looked less like the popular image of sharpened bananas, more like sharpened Toblerone segments.

[Halichoeres]

Ignoring the beak for a minute, if Ramphorynchus was swooping and dabbling for fish for a living, does that count as being constantly hydrated?

Tyrannosaurus tooth to skull ratio are actually not too different then varanids at skull length parity.

Yup! The skulls of monitors and other lizards can be surprising with how toothy they are. In life, even with gaping mouths, the most you can often see are nubs mostly covered with gums. Here's a relevant Tetzoo post from a while ago.
So pushing Tyrannosaurus' teeth back into their sockets and adding a hypothetical thick layer of gum tissue, they could have looked less like the popular image of sharpened bananas, more like sharpened Toblerone segments.

Sharpened Toblerone segments is a great visual! 

[Papi-Anon]

Whelp, time to redo my allosaurus CAD figure's jaws and teeth.

No pictures at the moment, but a recent sculpture I've been working on of Dimetrodon has lips that cover the teeth (of course now it has a wide gap between its lower jaw's gums and lips to fit the top row of teeth).

[Bowhead Whale]

I see what you mean: the teeth on the Tyrannosaurus skull do not have their roots on the extreme edge of the jaws like on a crocodile skull, there is space between the edge of the jaws and the roots of the teeth. That tends to show, in my opinion, that Tyrannosaurus rex did have lips and the space I described was meant to protect the lips of T-Rex from being wounded by its own teeth...

[stargatedalek]

Quite a bump, but since no one else mentioned it I'm just gonna say that Rhamphorynchus is about the worst possible comparison for a theropod. Firstly, it was an aquatic animal, it swam underwater to catch fish (whether it dived into the water like a gannet or just sort of landed then swam is irrelevant), and secondly at least part of the jaws were likely covered by keratin making lips impossible.

[Bowhead Whale]

Quite a bump, but since no one else mentioned it I'm just gonna say that Rhamphorynchus is about the worst possible comparison for a theropod. Firstly, it was an aquatic animal, it swam underwater to catch fish (whether it dived into the water like a gannet or just sort of landed then swam is irrelevant), and secondly at least part of the jaws were likely covered by keratin making lips impossible.

I was aware of that difference of lifestyle between the two animals myself when I made my comment. Our friend put the Ramphorhyncus skull here as an example of what a skull looks like when an animal CANNOT HAVE LIPS. And that animal who cannot have lips is very different from other animals who MIGHT HAVE LIPS, like the Tyrannosaurus.

[Patrx]

Mark Witton discusses the the textures on tyrannosaur skulls and their implications for life reconstructions.

I'd love to see more complete work and discussion on this subject; there are so many questions and possible answers.

[Halichoeres]

I personally think they all had old-timey waxed mustaches.

[Neosodon]

Interesting. We don't usually see lizards being used in dinosaur reconstructions.

[Minmiminime]

Finally! I was waiting for a reconstruction based on that paper

[Patrx]

Finally! I was waiting for a reconstruction based on that paper

The Carr et al. (2017) tyrannosaur paper? This is more in-response to that paper than based directly on it. Also relevant is Barker et. al (2017) regarding the facial anatomy of Neovenator. According to Mark:
"...there is another version of this text that goes into a little more detail - Barker et al. are mentioned there. The plan is to turn this into a more formal response at some point".

[John]

To me,the truth is somewhere in between the Carr et al. paper and the upcoming response to it.Like Witton,I have my doubts about the crocodile face thing,but I do agree with Carr that tyrannosaurids did not have "lips" covering their teeth when their mouths were closed.