Dinosaur lips?

[HD-man]

The statement "...to remind  "lipless" proponents the burden of proof on them." is simply untrue.

How so? A lot of evidence was laid out very clearly & it shows that lips in T.rex are more likely than not. Thus, it's up to "lipless" proponents to present more evidence showing otherwise (which they so far haven't).

So I'm going to have to disagree with you and WarrenJB on this one.Your arguments just seem to come more from a general dislike of Thomas Carr then anything else.

How do you figure that? Besides the fact that both his post & mine consisted mostly of pointing out the aforementioned evidence, I didn't mention Carr at all & he only said, "the burden of proof is on Carr to properly explain how tyrannosaurids go against the grain" ("the grain" = "the aforementioned evidence"). Thus, your Carr claim is baseless at best & ad hominem at worst.

[Dinoreplicas]

There's no direct evidence for the exact state of theropod oral tissues so it's all interpretation and speculation.

I used to be about 60/40 in favour of lips but since the study by Carr et. al, I guess I'm closer to 50/50.

[WarrenJB]

Yup. As Strick says, there's no direct evidence for or against tyrannosaurid lips; but as HD-man lays out, there's a lot of indirect evidence, and not too much of it falls on the side of 'lipless'.

Carr's stance seems almost like an afterthought to the description of D. horneri, even though that's what pop-sci picked up and ran with. Witton's stance begins with the rebuttals of 'foramina along the maxilla can mean different things' and 'skull texture =/= skin just like a crocodile' (with examples and comparisons to back it up*), and goes on from there.

*Though I can't remember if anyone's mentioned that the skull-hugging, texture-dependent, cracked skin of crocs, is, in the illustration accompanying Carr's paper, draped right over the area of the snout occupied (or voided) by a massive antorbital fossa. Carr's example of crocodile-like bone texture in tyrannosaur skulls is all but limited to a dorsal patch of the maxilla - a relatively small part of the tyrannosaurid skull - and Witton just showed how it's not very croc-like at all.

Though that's getting off the topic of lips. For that, there's the fact that lips, or some kind of tooth-covering labial tissue, are the default for tetrapods, and beyond. I feel this is stronger than even the arguments for or against tyrannosaur feathers: you're not just placing tyrannosaurids with some other coelurosaurs, or even (in this case) some other archosaurs - you're placing them with vertebrata! It's right up there with the 'necks lie' hypothesis for sauropods, IMO.

So the presence of labial tissues for practically demands to be the default state for tyrannosaurids. This is why I feel the burden of proof is on those who propose liplessness: to provide direct evidence; or a strong argument based on indirect evidence, of specialisations or exceptions (as crocodylians are showing themselves to be) that would act against the presence of lips.

I just don't think Carr et al have been very thorough in that regard.

I can also get behind Stargatedalek's post. Tyrannosaur teeth are more robust than other theropod teeth, but still fall short of a comparison with conical crocodile teeth. The incisiform premaxillary teeth have D-shaped cross-sections and ridged posterior surfaces. The big maxillary 'bone-crunching bananas' are recurved, elliptical in cross-section, and have fairly unique, theropod-specific serrations. They're more complex than crocodile teeth. If their fine structure needs to be preserved by moistening the enamel (to prevent wear rather than cracking of the enamel) in ways that croc teeth don't, I can see them needing a set of enclosing lips.

[spinosaurus1]

[John]

There's no direct evidence for the exact state of theropod oral tissues so it's all interpretation and speculation.

I used to be about 60/40 in favour of lips but since the study by Carr et. al, I guess I'm closer to 50/50.

Thank you for this.I've read all the literature for and against "lips",including everything posted here which is helpful and interesting,but it is all still just speculation.There is no stronger evidence for "lips" than not at the moment.I never said it was impossible,but I need to see something more solid than just speculation that will likely change again and again back and forth until something better turns up,if ever.

The statement "...to remind  "lipless" proponents the burden of proof on them." is simply untrue.

How so? A lot of evidence was laid out very clearly & it shows that lips in T.rex are more likely than not. Thus, it's up to "lipless" proponents to present more evidence showing otherwise (which they so far haven't).

So I'm going to have to disagree with you and WarrenJB on this one.Your arguments just seem to come more from a general dislike of Thomas Carr then anything else.

How do you figure that? Besides the fact that both his post & mine consisted mostly of pointing out the aforementioned evidence, I didn't mention Carr at all & he only said, "the burden of proof is on Carr to properly explain how tyrannosaurids go against the grain" ("the grain" = "the aforementioned evidence"). Thus, your Carr claim is baseless at best & ad hominem at worst.

Only indirect evidence,which is just as much speculation as what was in Carr et. al.'s study.As I said,I need something a bit more solid than that.And no,nothing I said was baseless as this whole thing was taken as "kicking Mark Witton in the shins" for something he didn't argue for (the tooth enamel thing) by WarrenJB who goes on to say "to bruise his (Carr's) shins a bit"..before just dismissing out of hand anything he had to say in what seems like irritation.Then it gets backed up by you with the reiteration of his opinion of the burden of proof being on those that don't agree with the "lips" bit.But I think there is a misunderstanding here because I never attributed the enamel idea with Witton.I never saw any mention of it in any of his posts,or ever seen him use that line of argument for it anywhere,just inferences from the skulls.

[Faelrin]

Regardless of the evidence (or lack there of) right now, I'm leaning towards lips since most animals have them, and honestly I think without lips (or beaks in the case of birds) theropods just look a bit ridiculous. I haven't read the entire article yet, and I'm not sure where the science lies with what looks to be lizard lips on that reconstruction, but at least its probably a better fit then mammalian lips.

[John]

Regardless of the evidence (or lack there of) right now, I'm leaning towards lips since most animals have them, and honestly I think without lips (or beaks in the case of birds) theropods just look a bit ridiculous. I haven't read the entire article yet, and I'm not sure where the science lies with what looks to be lizard lips on that reconstruction, but at least its probably a better fit then mammalian lips.

Yes,should they have "lips",it would be more like a lizard's inflexible lip like covering as seen on the reconstuction on the first post of this thread than the big floppy bulldog lips I've seen on some pictures.

[Dinoguy2]

A related issue: people need to quit depicting theropods with their jaws maximally closed. Just the jaw muscles alone would prevent this, and it renders the whole "overbite " issue moot.

[Moldovan0731]

Hmm, would also have loved to see something more obscure.... Giganotosaurus seems to be the new black... or better Rex in our cause. However, I like the fact it seems to stand on its finely proportioned feet without a stand and that it comes in a subdued but not unattractive paint job, fitting for a creature that size in my opinion. What I wonder though.... does it have lips, are the teeth covered once the mouth is closed? And which sauropod figure can I reasoanbly pose next to it? PNSO Huanghetitan should work as a stand in for Argentinosaurus, probably?

Well, lips are only restricted to mammals, there is no diapsid with lips. Said this, as you asked, if the teeth are covered when mouth closed, there aren't, this is because we follow the last study of Carr et al. (2017) who found that the texture in crocodylians jaw is very similar to that of tyrannosaurids (and probably other large theropods), and therefore suggesting a similar functional mechanism in jaws and no "lips". However, the debate is open, and until more evidence or conclusive studies are published, both options are valid.

Barker et al. (2017) is another paper favouring liplessness if I know well.

[stargatedalek]

All modern diapsids that aren't crocodilians or birds have lips. Crocodiles are aquatic and so make for a poor example irregardless of textures, and birds are completely non applicable because of their beaks.

I could just as easily use the evidence of tough covering on Tyrannosaur faces to suggest this as evidence they were feathered, as it shows they had hardened surfaces around their mouths like birds do. Why is it not equally ridiculous to claim that as evidence they had exposed teeth? Surely because they share one superficial characteristic, I can now infer another?

Short of evidence they were aquatic, only preserved soft facial tissue would ever make exposed teeth the realistic option.

Lizards, snakes, and even turtles (those without hard beaks) have lips. "Muscular lips" are exclusive to mammals, but lips are the norm among terrestrial vertebrates.

[Lanthanotus]

All modern diapsids that aren't crocodilians or birds have lips. Crocodiles are aquatic and so make for a poor example irregardless of textures, and birds are completely non applicable because of their beaks.

I could just as easily use the evidence of tough covering on Tyrannosaur faces to suggest this as evidence they were feathered, as it shows they had hardened surfaces around their mouths like birds do. Why is it not equally ridiculous to claim that as evidence they had exposed teeth? Surely because they share one superficial characteristic, I can now infer another?

Short of evidence they were aquatic, only preserved soft facial tissue would ever make exposed teeth the realistic option.

Lizards, snakes, and even turtles (those without hard beaks) have lips. "Muscular lips" are exclusive to mammals, but lips are the norm among terrestrial vertebrates.

Yeah, well we had this discussion quite a while ago when said paper (Carr 2017) was published and I am all in with you... may just add...

"Lips" may require a more precise definition, buthard fact is that practically all living vertebrates (aquatic or not) can close their mouths shut so nothing on the inside can be seen and teeth are covered up. That is true for all classes of animals and exceptions are very few. Just a few species of fish and all crocodylians have bared teeth, and no terrestrial animal boasts bared teeth that are used for the main purpose teeth evolved for - biting and chewing.

[Moldovan0731]

All modern diapsids that aren't crocodilians or birds have lips. Crocodiles are aquatic and so make for a poor example irregardless of textures, and birds are completely non applicable because of their beaks.

I could just as easily use the evidence of tough covering on Tyrannosaur faces to suggest this as evidence they were feathered, as it shows they had hardened surfaces around their mouths like birds do. Why is it not equally ridiculous to claim that as evidence they had exposed teeth? Surely because they share one superficial characteristic, I can now infer another?

Short of evidence they were aquatic, only preserved soft facial tissue would ever make exposed teeth the realistic option.

Lizards, snakes, and even turtles (those without hard beaks) have lips. "Muscular lips" are exclusive to mammals, but lips are the norm among terrestrial vertebrates.

Mark Witton just stated his opinion, nothing more, nothing less. He hasn't gone through the same necessary steps like Carr did. Carr's paper went through peer review process and was published through scientific literature. Witton's observations and statements have not gone thought he same amount of peer review and never made it to scientific journals. His post is just a blog post, so unless (and until) he goes through exact same steps, it is simply just another person's opinion.

[DinoToyForum]

Lips lips lips, talk about lips, get your lip fix here!

I moved some off-topic discussion here. I might rename this thread the "dinosaur lips thread" so we can find it easily...  I hope that's okay @Patrx 

[Patrx]

I might rename this thread the "dinosaur lips thread" so we can find it easily...  I hope that's okay Patrx 

Good idea!

[Minmiminime]

I might rename this thread the "dinosaur lips thread" so we can find it easily...  I hope that's okay Patrx 

Good idea!

I'm thoroughly enjoying reading this thread! I'm on the side of enclosed teeth as a general rule, however...
...there were terrestrial crocodilians who were unlikely to have sheathed teeth, and also, pterosaurs. I know of one particularly brilliant and prolific palaeoartist who's played around with sheathing the teeth of Dimorphodon and I'm not sure I can get totally on board with that one 🤔 But I'm perfectly happy with reconstructions of either condition in dinosaurs. It's all part of the joy of wonder!

[stargatedalek]

All modern diapsids that aren't crocodilians or birds have lips. Crocodiles are aquatic and so make for a poor example irregardless of textures, and birds are completely non applicable because of their beaks.

I could just as easily use the evidence of tough covering on Tyrannosaur faces to suggest this as evidence they were feathered, as it shows they had hardened surfaces around their mouths like birds do. Why is it not equally ridiculous to claim that as evidence they had exposed teeth? Surely because they share one superficial characteristic, I can now infer another?

Short of evidence they were aquatic, only preserved soft facial tissue would ever make exposed teeth the realistic option.

Lizards, snakes, and even turtles (those without hard beaks) have lips. "Muscular lips" are exclusive to mammals, but lips are the norm among terrestrial vertebrates.

Mark Witton just stated his opinion, nothing more, nothing less. He hasn't gone through the same necessary steps like Carr did. Carr's paper went through peer review process and was published through scientific literature. Witton's observations and statements have not gone thought he same amount of peer review and never made it to scientific journals. His post is just a blog post, so unless (and until) he goes through exact same steps, it is simply just another person's opinion.

I said nothing about Witton or his blog. My statement is based almost entirely on modern analogues. Animals with exposed teeth always have teeth specifically adapted to compensate this, even aquatic crocodiles.

Just because something gets peer reviewed and published doesn't automatically make it correct. I think a lot of us here have more than the general hobbyist level of understanding of paleo-art reconstruction (see, =/= paleontology), and know what we're talking about when we question a papers conclusions. Life reconstruction feels sometimes like another field entirely.

I might rename this thread the "dinosaur lips thread" so we can find it easily...  I hope that's okay Patrx 

Good idea!

I'm thoroughly enjoying reading this thread! I'm on the side of enclosed teeth as a general rule, however...
...there were terrestrial crocodilians who were unlikely to have sheathed teeth, and also, pterosaurs. I know of one particularly brilliant and prolific palaeoartist who's played around with sheathing the teeth of Dimorphodon and I'm not sure I can get totally on board with that one  But I'm perfectly happy with reconstructions of either condition in dinosaurs. It's all part of the joy of wonder!

Crocodiles even despite being aquatic already have teeth adapted to combat exposure. Their teeth are thick and conical for maximum durability, and they have no serrations to get worn away.

[Patrx]

I'm thoroughly enjoying reading this thread! I'm on the side of enclosed teeth as a general rule, however...
...there were terrestrial crocodilians who were unlikely to have sheathed teeth...

That's something I've been wondering about, though–should we be reconstructing terrestrial suchians with exposed teeth?

[Lanthanotus]

I'm thoroughly enjoying reading this thread! I'm on the side of enclosed teeth as a general rule, however...
...there were terrestrial crocodilians who were unlikely to have sheathed teeth...

That's something I've been wondering about, though–should we be reconstructing terrestrial suchians with exposed teeth?

I think yes.... in fact, I'd deem the exposed teeth in aquatic crocodylians a secondary acquirement, evolved for maximum effectiveness of the water based ambush predation technique and underwater bite predation.

[DinoToyForum]

I merged two similar threads. There is a third that I will probably merge so that this thread becomes the catchall dinosaur lips thread.

[suspsy]

Publishing your findings in a peer-reviewed journal is the official and proper method of carrying out paleontology, but as with all branches of science, that doesn't mean you've had the final, definitive word on a topic. Far from it. Scores of paleontological papers have been rendered moot over the decades as a result of new discoveries or revealed errors. For example, the recent paper claiming that Spinosaurus was a poor swimmer has come under scrutiny from palaeontologists Darren Naish and Thomas Holtz due to the fact that the authors did not study the available fossil material first hand and appear to have reconstructed the animal's torso too narrow. And just because Naish and Holtz haven't officially published their objections, it doesn't invalidate them.