Functional Morphology of Animal Feeding Apparata

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Yup.

But now I just gotta find a way to get full access.

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Ooooooo...kaaay...are you talking to me or Greg Erickson or both?

I got the impression that the whole bite pressure thing he brought up was simply to illustrate the fact that a huge amount of force was being concentrated all on the tooth tips.

1,311,919.02 psi is roughly 9,000 N/mm2. How could an animal ever exert such a tooth pressure? Bones are supposed to break at a few 100 Newtons/mm2, and in order to make higher values possible, you'll need another material that can withstand such pressures. Yes, a quick bite will increase the numbers somewhat, but it will still remain far away from thousands of Newtons/mm2. Furthermore, 9,000 N/mm2 is distinctly more than the compression strength of dental enamel, which means that T. rex would destroy its own tooth tips.
So that 9000 N/mm2 figure is a mere hypothetical number without any significance in reality.

Well I don’t know, I wasn’t around to observe the evolution of Tyrannosaurus rex, and therefore don’t know why exactly it would need to be able to achieve any quantitative value of strength for bone cracking (whatever that may be). I just went with published figures, tried making deductions with some math on my own, and looked at what I got. Note, though, that even Gignac & Erickson’s untouched tooth pressure exertion estimates far exceed the apparent ultimate shear stress of cortical bone, as they state in the results section of their paper.

I’m not necessarily defending what I wrote back then (because I don’t know just how hard the thing bit, I just know it bit hard), but...is the compressive strength for enamel necessarily universal among the animal kingdom? I’m no expert on that matter, but I’m not yet ready to completely accept it being unanimous among all animal taxa (the way to make me do so, of course, would be to direct me to a reliable source/evidence suggesting so). In a similar manner to how lions supposedly have claws far harder than our fingernails (despite being made of the same substance, thus making me question that there’s necessarily one single set hardness to the material), I do wonder if the compressive strength of enamel varies within taxa. After all, even Gignac & Erickson’s highest tooth pressure figure far exceeds the compressive strength of enamel (or at least what I can find of it; 384 MPa according to this paper?).

[theropod]

What and whom are you responding to?

Enamel having massively different compressive strength across taxa can be ruled out, how do you see that working?
There are certainly structural modifications at the microscopic and nano-scale (such as prism orientation) and chemical variations (such as flourine content) that might increase the toughness and compression strength of enamel in some taxa, but up to 9000 MPa is unheard of and hardly feasible.
Even bone is usually assumed for simulations to hava broadly similar strength properties across taxa (even though bone, unlike enamel, has a large organic component as well as much more complex structural variation, meaning it could actually be expected to be more variable).

www.researchgate.net/profile/Wighart_Koenigswald/publication/19560721_Changes_in_the_tooth_enamel_of_early_Palaeocene_mammals_allowing_dietary_diversity/links/0deec5163e79644f48000000/Changes-in-the-tooth-enamel-of-early-Palaeocene-mammals-allowing-dietary-diversity.pdf
This paper cites the compressive strength as 95-385 MPa. That’s already a pretty impressively large range, but (if legit, and not including demineralized/weakened enamel too) this can be explained by the aforementioned structural and chemical variation. And yet the width of that range pales compared to extending that 20 times upwards. That would quite simply be the most amazing adaption in the world, if one animal could grow dental apatite 20 times stronger than the dental apatite of other animals.

So yes, tooth pressures in the thousands of megapascals are certainly purely hypothetical. And in all honesty, why would an animal even need to produce tooth pressures that high, when the compressive strength of bone is just 170 MPa? So creating a tooth pressure just above that, but lower than the failure strength of enamel, will be enough to essentially crush any bone. Since the teeth become much wider at the base and I don’t know how the figures you are discussing are measured, presumable a lot more force would be required for this the deeper the teeth penetrate, when biting a large bone, and additionally in order to not just crush but also shear or snap such bones, which explains the need for a powerful bite force.

So whoever it’s from, I agree with your quote. It makes a lot of sense. If a T. rex really bit down on a hard object’s surface (i.e. higher compressive strength than its teeth) with only its tooth tips making contact (i.e. minimal area over which bite force is distributed) at full force, it would likely break its teeth. Such fractures on fossil theropod (and other) teeth aren’t exactly unheard of. In reality though, most things a T. rex would encounter would actually be softer (lower compressive strength) than its teeth, so pressures like those hypothetical figures you cite couldn’t be generated in the first place, unless we envision T. rex chewing rocks.

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What and whom are you responding to?

Aurelius replied to one of my ~1 year old posts here. A few hours after I replied, I could not see his post anymore. For that matter, I couldn't find his name in the members list or in posts that I remember he liked.

Either he's trying to make me appear insane (/notserious) or he just left the forum and left no trace of himself (he only had 13 posts after curiously replying to me, so it wouldn't have been much).

So yes, tooth pressures in the thousands of megapascals are certainly purely hypothetical. And in all honesty, why would an animal even need to produce tooth pressures that high, when the compressive strength of bone is just 170 MPa?

But Gignac & Erickson already report tooth pressures generated at T. rex's tooth tips well above enamel's compressive strength, no matter how you slice it. Are they also purely hypothetical?

"Apical tooth pressures (1 mm crown height) range from 718 to 2,974 MPa (104,137 to 431,342 pounds per square inch [psi]) (left M3 of BHI 4100 and right M5 of MOR 980, respectively) (Supplementary Table S2)."

Like I said before, I'm not really defending stuff anymore. I'm not even talking about my calculations from a year ago (that Aurelius decided to respond to that is another case of a person quoting stuff I said a while back under the assumption that I fully believe it now). I'm just confused. Even if you take that 718 MPa figure Gignac & Erickson calculated that's well above the 385 MPa upper bound compressive strength of enamel, and even more above the strength of bone.

I'm confused, even that minimum tooth pressure should be enough to then destroy the enamel tips of T. rex's teeth. Do all animals biting into bone (even though there's definitely variation into how hard they bite relatively speaking and whatnot) generate the same pressures, just enough to break bone but not enough to break their own teeth?

[theropod]

Yes, no matter how you slice, it a tooth cannot excert a pressure that exceeds its own compressive strength. Actually, it cannot excert a pressure on bone that is greater than the bone’s compressive strength either, because if that compressive strength is exceeded, the bone will simply disintegrate locally until the pressure and strength properties even out. You simply cannot use a structural element to apply a pressure greater than that element can withstand. If you try to put 700MPa on a tooth tip, that tooth tip will shatter when its maximum compressive strength is exceeded (assuming that there is no bending moment whatsoever, otherwise it will be earlier). However, that only works if you push the tooth against something stronger than enamel. If, like bone, the other material is weaker, the tooth will penetrate, exactly so deep that the larger area will make the pressure drop below the strength of the mmaterial.

That’s for compression, shear works very differently (the strength is proportional to the cross-sectional area of the structure in the same plane as the acting force, not the surface area of contact perpendicular to it). That’s why to shear a whole bone in half, you will need a much greater amount of force than to simply penetrate with a single tooth tip. That is also why I can push the tip of my knife into the surface of a bone without being able to excert the equivalent of a T. rex bite force, or enough force to break the entire bone in half.

We also have to keep in mind the area over which the pressure is applied. The tooth pressure figures from Gignac & Erickson are the result of applying the bite force to a single tooth tip (at 1mm of crown height), so an extremely small area. For starters, the number of teeth is unrealistic. There’s almost no scenario where a T. rex biting something wouldn’t make contact with at least a few at once. But 1mm is also a very small penetration depth, I don’t think anybody doubts that it could penetrate bone that deeply, but its also not very impressive at all. But take a single tooth with a diameter of 4cm, and let’s for the sake of simplicity assume it is circular. This would simulate the pressure it would take to push the tooth in completely. The cross-sectional area would be (40mm/2)^2*pi=1257mm².
Let’s say that’s a posterior tooth biting with the same 57KN bite force at posterior teeth originally estimated by Bates & Falkingham. And all of a sudden, the pressure drops down to only 45 N/mm², well below the compressive strength of both enamel and bone.
We can take that further in order to estimate how large the diameter of a tooth would be up to which that bite force could push it into bone, all we need to know is the compressive strength of bone (let’s take 170MPa), (57*10³N)/(.5d)^2*pi)mm=170N/mm²→→((57*10³N)/170N/mm²/pi)^.5*2=d=21mm. So hypothetically, biting with just a single tooth, it could probably penetrate compact bone up to a tooth diameter of 2cm. Just eyeballing it, that seems about right when I remember the famous bite marks on the Triceratops pelvis.

This is still very simplistic though, as much of the bone bitten into would actually not be compact bone, and thus far easier to puncture, and we’d get a complex interplay of trabecular and hollow bones whose thin bone lamellae or walls would then be subjected to shear stresses and would probably fail in shear instead of compression. So that above figure only refers to a thick piece of compact bone, which I’m not sure would be actually encountered that often in life, as even thick dinosaur bones have a medullary or pneumatic cavity below relatively thin walls and/or are composed of spongiosa. But we also should not forget that this assumes the whole force is concentrated onto a single tooth, whereas in life, if a tooth penetrated that deeply there would have to be adjacent teeth making contact too.

Gignac & Erickson actually suggest that shearing was the primary mechanism by which bones were fragmented, because of the relatively low shear strength of bone, and I think that is actually an observation I have made before myself, because of the way the maxilla and maxillary dentition laterally overhang the dentary, just as in a pair of scissors. So that way, it’s the total force applied divided by the bone cross-section that matters. In reality, of course, both compression and shear forces would work in concert, teeth would first penetrate bone up to a certain depth, which would help weaken the bone (especially if done repeatedly) and provice a good grip, and at the point were the tooth pressure doesn’t bring it any further, the bone, if it is small enough, can be completely fractured by the shear forces acting between the lower and upper tooth rows.



That’s one reason why the popular reliance on essentially meaningless "psi-figures" for all sorts of strength (be that bite force, or eagle grip strength) is very stupid.

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I made a size comparison between the skulls of Daeodon and two tyrannosaurids, Nanuqsaurus and Lythronax, just to see how the feeding apparata of these predators compare (and to practice my rudimentary comparison creation skills). Well, rather, I used a skull size comparison theropod made a while back and posted into the Nanuqsaurus profile here and added a Daeodon skull in to scale. Daeodon's skull is scaled to 90 cm long. Does this look right?

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A new paper about exceptional adaptive changes in bite force. Most animals, it seems, don't show rapid and strong selection for bite force, even including some powerful biting macropredators (although, according to their supplementary information, felids, chiropteran subclades, and all dinosaurs showed some degree of elevated rates in the posterior sample (i.e. >50%), just not at the 95% threshold).

royalsocietypublishing.org/doi/10.1098/rspb.2018.1932

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Gonna go back to T. rex vs. jaguar bite force. So, I have Sakamoto et al.'s data for bite force and body mass. I used the bite force estimates that they themselves made, being the most recent (and probably only) study in which direct comparison between the two species can be made. So, the jaguar specimen they examined for their own estimate weighed 97 kg. The maximum bite force they estimated for it (F_Bite2) was 2,026.300331 Newtons. There was also F_Bite1, which, in Sakamoto's words in an email response to me, is "...the maximum functional bite force for that entry, which corresponds to bite force that is important in procuring/killing prey. That is, the bite force for the “killing” bite in the case of predators and crushing bites for seed eaters and maybe bone crushers. Typically, these will be canine-biting for most carnivores, and anterior biting positions for dinosaurs." For the jaguar, this "functional bite force" was 1,392.903906 N.

There were two Tyrannosaurus specimens Sakamoto et al. used for their own estimate, BHI 3033 (Stan) and AMNH 5027; both are estimated at 8,385 kg. I don't buy this, considering this rivals Sue in body mass (this comes from Hutchinson et al., 2011). blaze once did a GDI of Stan and got almost 7t (theropod specified some 6.9t or so). Likewise, Asier Larramendi did a GDI on it that resulted in ~6.5t when assuming a density of 0.95 kg/liter; adjusting it to ~0.915 kg/liter (apparently the approximate value for Scott Hartman's theropod GDI models) we get ~6.26t for Stan (see the comments section below). Because the size of Stan's skull and jaw muscles stays constant here, either it's got a proportionately smaller head the larger its whole body is, resulting in a proportionately weaker bite, or it's got a proportionately larger head the smaller its whole body is, resulting in a proportionately stronger bite.

So now that that's set, scaling our 97 kg jaguar up to 6.26 tonnes...

((cube root of (6260/97))²)*2026.300331

...we get a maximum bite force of 32,601.5975 N. Using F_Bite1 we get 22,410.74129 N. How hard did Stan bite in comparison? With a maximum force of 45,379.51362 N (F_Bite2); F_Bite1 was 29,816.96361 N. Interestingly, they calculated AMNH 5027 to have bitten even harder than Stan (48,505.14364 N for F_Bite2, 31,870.63821 N for F_Bite1).

Now let's try Franoys' estimate of 7,722 kg for Stan.

((cube root of (7722/97)²)*2026.300331

...we get 37,498.09376639718 N max and 25,776.65337940908 N using F_Bite1.

Even scaling the jaguar up to 8,385 kg, as per the estimate Sakamoto et al. used for Stan...

((cube root of (8385/97)²)*2026.300331

...we get 39,614.85195 N max and 27,231.73913 N using F_Bite1.

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Edit: I wanted to see what numbers we'd get if we scaled according to skull length as opposed to body size, as the skull is the actual thing producing the force of the bite.

According to the data in Sakamoto et al.'s supplementary material a 97 kg jaguar has a skull ~22.7 cm in length. Let's scale this up to the inflated mass Sakamoto uses for Stan:

(cube root of (8385/97))*22.7=100.369779 cm skull

Now that we know how big an 8.385t jaguar's skull is, let's use this to find bite force.

((100.369779/22.7)²)*2026.300331=39,614.85191 N.

And because I don't believe that Stan was as massive as Hartman's Sue:

(cube root of (6260/97))*22.7=91.05281775 cm skull

((91.05281775/22.7)²)*2026.300331=32,601.5975 N.

Or alternatively:

(cube root of (7722/97))*22.7=97.65141593 cm skull

((97.65141593/22.7)²)*2026.300331=37,498.09377 N.

Oh wow, we end up with pretty much the exact same values for bite force using skull length as we did using when body mass (keep in mind, this is F_Bite2). So yeah, I think my calculations above using body mass hold up.

Btw, the skull length and body mass figures for the jaguar were stated to come from Sakamoto et al. (2010), which I assume is this paper->.

...

So, in conclusion, Tyrannosaurus seems to bite about as hard, if not harder, for its size compared to a jaguar. And yes, their own bite force estimates for the two were the same (labeled 'this study', as opposed to a previous work), the dry skull method. So even if these numbers aren't accurate in absolute terms, they should at least give us a pretty good idea of how hard these animals would bite relative to each other.

I couldn't tell whether or not Sakamoto et al. considered the jaguar (and other felids) to have had exceptionally powerful bites or not. Their text and figures suggested they didn't, or at least not to the same extent as say, the large ground finch. Yet not too long ago, I had emailed Sakamoto my questions about this paper, and he considered the jaguar to have had an exceptionally powerful bite for its size, in light of his paper's findings. Evidently, if the jaguar has an exceptionally powerful bite for its size, then so does Tyrannosaurus. Even more so, in fact. On the converse, if Tyrannosaurus has a more or less "average" bite force for its size, then so does the jaguar. Even more so, in fact.

Also, I didn't drill it through my skull then that the jaguar really deserves to be brought up among the hard-biting, durophagous predators (other conical toothed macropredaceous cats probably aren't too far behind, either). I reckon T. rex does too...to the surprise of literally no one.

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Smok wawelski was a bone crusher.

www.nature.com/articles/s41598-018-37540-4

Would anyone care to assist me in finding any scientific article regarding the bite force of H. horridus? I've only gotten a Tapatalk page (to another AvA forum) that provides any information about an actual scientific bite force estimate. It does reference some stuff Stephen Wroe did with H. horridus (which can be seen in the documentary Prehistoric Predators), so this is indeed legit, but I don't think I've been able to find the actual study online.

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Some information about the thylacine.

The thylacine brain case was relatively small compared with canids, perhaps because it did not have their sophisticated social organisation. Thylacine had more teeth than canids and in common with the large dasyurids (Tasmanians devils and quolls) the carnassials were barely distinguishable from other molars whereas those of canids, felids (cats) and mustelids (weasels) are typically massive and prominent. The canine teeth of thylacine were somewhat rounded in cross section compared to those of canids which have a sharp trailing edge, better adapted for ripping. The thylacine skull was long and narrow, more so than that of a wolf Canis lupus, suggesting no specialisation for massive prey (a low aspect ratio giving more power) and indeed prey of the thylacine was mostly other marsupials smaller than itself (e.g. wallabies). The changing shape of thylacinid skulls over the eons shows clear evidence of evolutionary convergence towards large canids specialising in pursuit; evidence perhaps of the thylacine’s evolutionary trajectory. Despite not being relatively powerful the thylacine’s long narrow jaw was still very large, absolutely strong and could reportedly deliver a precise bite (the thylacine searcher David Fleay showed the author the famous scar on his derrière from such a bite received in the Hobart zoo). Thylacines did occasionally kill large hunting dogs in self-defence. Thylacines were entirely carnivorous and wild individuals were reportedly reluctant to scavenge, although there is a report of one feeding on the carcass of a stranded whale and they occasionally got caught in traps baited with meat.

beta.capeia.com/zoology/2016/09/07/thylacine-the-improbable-tiger

That thylacine canine teeth were more ovoid, and therefore stronger mediolaterally than most canid canine teeth, is supported by Jones & Stoddart (1998).

Canine shape, based on the ratio of canine strengths of antero-posterior over medio-lateral directions (Sy/Sx), for the thylacine (1.42) lies intermediate between those of the spotted-tailed (1.33) and eastern quoll (1.50) (Fig. 1). The value for the devil (1.14) is the lowest of any of the carnivores, marsupial or placental (Van Valkenburgh & Ruff, 1987), presented in this analysis. Thylacine canines are more ovoid (lower value for ratio), and therefore stronger on the medio-lateral axis, than most canids in this analysis; the exceptions being several small canid species, the bush dog Speothos and four fox species including the red fox Vulpes vulpes, which have more ovoid canines than the thylacine (Fig. 1). The wolf has the most laterally compressed canines (highest ratio) of all of the carnivores in the analysis. Functional shape of thylacine canines is equivalent to that of all three hyena species, but is near the top of the range of values for the felids. Most felids have canines that are rounder in cross-section, and therefore stronger on the medio-lateral axis, than those of the thylacine (Fig. 1). Equivalent values for other placental carnivore families (Mustelidae, Viverridae, Procyonidae, Ursidae) were not available in the published literature.

s3.amazonaws.com/academia.edu.documents/34415463/-predatory_behaviour_thylacine.pdf?AWSAccessKeyId=AKIAIWOWYYGZ2Y53UL3A&Expires=1552799709&Signature=mdTkUfY2NXuSyzdmvegm9oCHi9o%3D&response-content-disposition=inline%3B%20filename%3Dpredatory_behaviour_thylacine.pdf

The thylacine's ability to kill animals like sheep (as had been claimed while it was still extant) has been questioned with findings suggesting that its jaw was too structurally weak to handle the stresses of large struggling prey (Attard et al., 2011). But even if this was true, a couple things need to be considered regarding sheep. As the Thylacine Museum (hyperlinked) website points out, the average size of Merino lambs up to 90 days old is less than the average weight of an adult thylacine at 29.5 kg (though, the average size for 90 day old lambs isn't much less than this), and so they could easily have been preyed upon. Second, one apparent idiosyncrasy of sheep is that when they are chased, they lie down. Dogs have been known to exploit this behavior and kill pursued sheep that lie down; a thylacine could do the same without having to cope with any struggle from a lying sheep.

According to contemporary descriptions (again, from the Thylacine Museum website), the thylacine made continuous, powerful snapping bites as opposed to biting, holding, and shaking (more analogous to jackals and a dog breed known as curs than they were to say, a bulldog), which I think would be consistent with the animal having a specific method of avoiding structural failure of its jaw if it really was relatively weak (along with the capability to deliver a precise bite, as per the first excerpt in this post). It has supposedly worked against large hunting dogs (and to lethal effect at that) and adult humans, which I hope I don't need to remind everyone are much larger than thylacines were.

It appears that, while the thylacine would have preferred prey that was smaller than itself given the functional morphology of its feeding apparatus, it could and would still deliver powerful bites to large animals, even those larger than itself (i.e. humans), in retaliation if needed.

EDIT 01/10/2022: One of the excerpts above states that thylacines occasionally killed hunting dogs in self defense. Here is one such account (source).

A bull-terrier was once set upon a wolf (thylacine) and bailed it up in a niche in some rocks. There the wolf stood, with its back to the wall, turning its head from side to side, checking the terrier as it tried to butt in from alternate and opposite directions. Finally, the dog came in close, and the wolf gave one sharp, fox-like bite, tearing a piece of the dog's skull clean off, and it fell with the brain protruding, dead.

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So, from what I can tell, there is a theory that says that the synapsid and diapsid temporal openings created more space for the jaw adductors (specifically the temporal muscles) to expand outwards and not squeeze the brain, something the anapsid condition did not allow (so larger, stronger jaw muscles did not allow a large brain to exist, and a large brain would not allow large, strong jaw muscles that would squeeze it to exist).

But if this is the case (and if not, correct me if I'm wrong), why did diapsids evolve two holes and synapsids just one?

Also, kind of unrelated question, do anapsids actually form a monophyletic clade, or is the term better used to describe a skull condition?

[theropod]

Also, kind of unrelated question, do anapsids actually form a monophyletic clade, or is the term better used to describe a skull condition?

If we mean it to include all Amniotes with the anapsid skull condition, it would be polyphyletic or at best paraphyletic. I think there was talk of a parareptile-turtle-clade, but the current state of things seems to be that turtles are pretty likely to be diapsids.

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From Bob Bakker's blog: this is how mammoth (and modern elephant) teeth compare to those of mastodons.

All mammoths have elephant-style molars. Each tooth crown is a gigantic vegetable processor, with many vertical plates of enamel set in a mass of dentine and cement. (Clever system.) As the uppers and lowers grind against each other, the cement and dentine wear away faster than the enamel. So, the enamel ridges stick up a bit more, guaranteeing that the tooth still has multi-edged cutting/chopping/mincing action until the tooth is totally worn out.

Now look into the mouth of our American mastodon and you’ll see the outstanding difference. The teeth are much smaller and simpler and have nothing like the food-processing power of a mammoth’s grinder. Each mastodon tooth is like a human molar or a pig molar. There are four or six main cusps in two rows, one inside and one outside. The total volume of one molar is one-twentieth that of a mammoth of the same body size. And when the enamel outer covering wore away in a mastodon, there were no vertical ridges of enamel left to cut and chop.

Clearly mastodons had to be more persnickety about their food choices than did the mammoths. Fossil stomach contents show that mammoths had an elephant-like diet: rushes, sedges, grass, branches, clumps of broad-leafed tree leaves. Stomach remnants and food bits caught between molars tell us that mastodons sought out soft bark from birch trees, soft branches, soft leaves, fallen fruit and nuts with just a wee bit of grass as a garnish.

After analyzing the dental differences, you’d predict that mastodons stayed in wetter, more wooded environments, rich in bushes and young trees. Mammoths would, on the contrary, penetrate far across the open meadows, grasslands and even deserts.

The census of fossil sites confirm your prediction.

Mastodon remains are abundant in bogs and swamps and sandbars from rivers flowing though forests. Mammoths, on the other hand, left many skeletons in sand dunes and rivers that flowed through open terrain. Occasionally both do occur in one spot, but usually one or the other dominates.

blog.hmns.org/2012/05/a-new-lady-in-town-part-i-why-priscilla-the-mastodon-isnt-a-mammoth-at-all/

From what I can tell (i.e. looking at the references on Wikipedia), other lines of evidence indeed support more of a browsing diet in mastodons as opposed to grazing on stuff like grass.

There was an analysis that suggests that mastodons were eating a lot more grass than thought based off of preserved dental calculus (link). However, as has been pointed out, that doesn't necessarily prove a preference for, or a substantial reliance on grass, as grass has hardened cells (phytoliths) that are much more likely to withstand chewing than those of browse, and are therefore much more likely to preserve and detect.

At the least, if what Bakker says about how well mastodon dentition compares to elephantid dentition in terms of resistance to long-term wear is true, grass may not hurt up to a point, but I can't see mastodons being the mixed feeders that modern elephants, and hence probably mammoths, are/were.

[theropod]

^Well, maybe mixed feeders, but only on softer types of vegetation. Humans are mixed feeders, just not specialized for high-fiber herbivory.

I also don’t think it’s a matter of grass damaging the teeth so much as the teeth simply not being equipped to efficiently process it. I mean obviously if the animal were to eat huge amounts of grass it would wear down the teeth, as it does in other grazers that chew, but it wouldn’t even get to that point because it probably couldn’t supply itself with sufficient calories.

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More Tyrannosaurus stuff for what it's worth.

Tyrannosaur skull performance
The highly complex modularity detected for the tyrannosaur (Figs 2A and 4A) indicates a very flexible skull regarding bite force distribution. Although loosely associated to others, the best-resolved modular associations are established by the lateral sides of the skull. The comparison to other amniotes and biological considerations result in the following assumptions.

1. Like all supposedly or clear kinetic forms studied herein (tuatara, chicken), a high degree of cranial mobility is possible in the tyrannosaur when compared to clear akinetic forms. This is consistent with the flexible sutures and the great number of links in the network of its cranial bones. This flexibility should be taken into account when reconstructing cranial performance. Like in alligator, a large snout is formed; however, different to alligator, streptostylic movement (via the epipterygoid, which connects the laterosphenoid and the quadrate process of the pterygoid) might have existed in the tyrannosaur. Although quite robust, the epipterygoid might have enabled some independent movements of the snout against the rest of the skull, like in tuatara, and an internal mobility between the upper and lower snout regions might have been beneficial in prey processing.

2. Internal snout mobility is supported by the formation of large fenestrations in the snout, which are mainly thought to enable pneumaticity, reduction of skull weight, and to buffer bite forces, but also reduces the contact area between bones and as such triggers higher mobility between them. The modular separation of the snout in upper and lower parts, related to snout fenestrations, not necessarily mirrors bite force distribution. It was reconstructed to travel from the canine-like teeth upwards when puncturing prey, a pattern also found in mammals, which do not have such a facial fenestration. The tyrannosaur was hypothesized to have not only punctured but also pulled its food. Associated to the presence of thecodont teeth, nesting in jaw alveoles, strain travels mainly along the upper jaw via the maxillar-jugal contact in the lower part of the snout module. Pulling food, as such, might have had a major influence in separating a lower and an upper snout submodule. In this context it is worth noting that, in contrary to the opossum, although specialized teeth are present on the premaxillary, no snout tip module was formed. Finite element analyses might be able to confirm this refined hypothesis for tyrannosaur when considering suture anatomy.

3. Although having a typical diapsid skull (like tuatara and alligator), a separation of a temporal bone module does not exist in tyrannosaur. This indicates that bite force might have been concentrated on a different aspect of the skull, namely the lower part of the adductor chamber, to which the muscles adductor mandibulae posterior and pseudotemporalis insert. The lower adductor chamber represents a separate module in our analysis. Voluminous jaw muscles have also been reconstructed for the upper part of the adductor chamber. However, within particular muscles, the distribution of different muscle fiber types and different fiber orientation, which generate specific force distributions, were not yet considered in any finite element analysis. Moreover, reconstructing fiber distribution in extinct species would be extremely time consuming. As such, AnNA, as presented here, in combination with biomechanic analysis is crucial to provide a first approximation to a more reasonable reconstruction of feeding biology in tyrannosaurs - and other fossil vertebrates.

www.nature.com/articles/s41598-018-37976-8

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Also, since the OP mentions postcranial features used to aid in feeding, I will include word on chalicothere forelimbs, for their use in hooking branches from trees.

Scientists have made all sorts of suggestions about how chalicotheres used their claws, such as digging up roots or fighting off predators. Detailed studies of their arm muscles and the wear on their claws rule these ideas out. The current scientific consensus is that chalicotheres sat up on their haunches, leaned on trees, and then stripped leaves from the branches with their hooked claws, much as ground sloths did.

The Princeton Field Guide to Prehistoric Mammals

Also, see Coombs (1983) for support of the above.

[theropod]

Badgers (Meles meles) have really weird jaw joints, the dentary condyle is enclosed and locked in place, so it can’t be disarticulated without breaking the joint, even when skeletonized.

Presumably this reinforced joint would make it very hard to dislocate in life. The flipside, as is particularly easy to measure in this case, is that the gape angle that can be achieved is severely limited, the maximum is about 45° between the ends of the jaws, and only 28° between the tips of the canines and the jaw joint:



I don’t know if or to what degree this might apply to other mustelids or how much variation there is, just thought I’d share it, since it might be relevant when discussing their predatory capabilities (that being said, of course badgers are less carnivorous than other mustelids, so they might be uniquely specialized).