Functional Morphology of Animal Feeding Apparata

[Supercommunist]

I guess they just wished researchers would include the animals estimated size in the abstracts. The first article I clicked seemed to be behind a paywall. I searched the article again and was able to find the full paper.

[Infinity Blade]

Aug 16, 2023 21:40:32 GMT 5 Infinity Blade said:

So apparently Saurosuchus had a weaker bite than Allosaurus. But it still had a strong skull. Would like to see biomechanical modeling incorporating the neck to see how it functioned.

Functional morphology of the Triassic apex predator Saurosuchus galilei (Pseudosuchia: Loricata) and convergence with a post-Triassic theropod dinosaur

Pseudosuchian archosaurs, reptiles more closely related to crocodylians than to birds, exhibited high morphological diversity during the Triassic and are thus associated with hypotheses of high ecological diversity during this time. One example involves basal loricatans which are non-crocodylomorph pseudosuchians traditionally known as “rauisuchians.” Their large size (5–8+ m long) and morphological similarities to post-Triassic theropod dinosaurs, including dorsoventrally deep skulls and serrated dentitions, suggest basal loricatans were apex predators. However, this hypothesis does not consider functional behaviors that can influence more refined roles of predators in their environment, for example, degree of carcass utilization. Here, we apply finite element analysis to a juvenile but three-dimensionally well-preserved cranium of the basal loricatan Saurosuchus galilei to investigate its functional morphology and to compare with stress distributions from the theropod Allosaurus fragilis to assess degrees of functional convergence between Triassic and post-Triassic carnivores. We find similar stress distributions and magnitudes between the two study taxa under the same functional simulations, indicating that Saurosuchus had a somewhat strong skull and thus exhibited some degree of functional convergence with theropods. However, Saurosuchus also had a weak bite for an animal of its size (1015–1885 N) that is broadly equivalent to the bite force of modern gharials (Gavialis gangeticus). We infer that Saurosuchus potentially avoided tooth–bone interactions and consumed the softer parts of carcasses, unlike theropods and other basal loricatans. This deduced feeding mode for Saurosuchus increases the known functional diversity of basal loricatans and highlights functional differences between Triassic and post-Triassic apex predators.

Okay so it looks like it did, in fact, have a strong neck. I mean, it doesn't say much beyond this (as far as I can tell), but yeah.

Saurosuchus galilei Reig is a “rauisuchid” from the Ischigualasto Formation (late Carnian, Late Triassic) located in central-western Argentina. This paper is the first detailed description of the proatlas-atlas-axis complex of this taxon, of a complete and articulated vertebral column, and of both scapulae. Overall morphology of the proatlas-atlas-axis complex is similar to that of other “rauisuchids”. This complex and the post-axial cervical vertebrae show the typical traits of an animal with a short and strong neck. The cervical vertebrae are anteroposteriorly compressed and dorsoventrally elongated. Vertebral laminae, interlaminar depressions, and lateral depressions on the centra are present in the cervical and dorsal vertebrae, as in other “rauisuchids”. The presacral series bears ventrally keeled centra and large transversal expansions of the distal ends of the neural spines. The caudal series shows axially compressed centra with a longitudinal ventral groove. The scapulae are very robust and have a brief expansion and a slightly curved scapular blade. The remarkable diversity of “rauisuchids” in general, makes a detailed analysis necessary in order to approach morphofunctional and phylogenetic problems; this new material is expected to contribute towards the solution of these problems.

ri.conicet.gov.ar/bitstream/handle/11336/98158/CONICET_Digital_Nro.7d94e086-486e-44c3-838e-81803baafb83_A.pdf?sequence=2&isAllowed=y

[Supercommunist]

Besides the kukri snake, does anyone know if there have been any cases where a non-venemopus snake's bite caused another animal to bleed to death?

[Infinity Blade]

Craniodental ecomorphology of the large Jurassic ichthyosaurian Temnodontosaurus

Marine amniotes have played many crucial roles in ocean ecosystems since the Triassic, including predation at the highest trophic levels. One genus often placed into this guild is the large Early Jurassic neoichthyosaurian Temnodontosaurus, the only post-Triassic ichthyosaurian known with teeth which bear a distinct cutting edge or carina. This taxonomically problematic genus is currently composed of seven species which show a wide variety of skull and tooth morphologies. Here we assess the craniodental disparity in Temnodontosaurus using a series of functionally informative traits. We describe the range of tooth morphologies in the genus in detail, including the first examples of serrated carinae in ichthyosaurians. These consist of false denticles created by the interaction of enamel ridgelets with the carinal keel, as well as possible cryptic true denticles only visible using scanning electron microscopy. We also find evidence for heterodonty in the species T. platyodon, with unicarinate mesial teeth likely playing a role in prey capture and labiolingually compressed, bicarinate distal teeth likely involved in prey processing. This type of heterodonty appears to be convergent with a series of other marine amniotes including early cetaceans. Overall, the species currently referred to as the genus Temnodontosaurus show a range of craniodental configurations allowing prey to be captured and processed in different ways – for example, T. eurycephalus has a deep snout and relatively small bicarinate teeth likely specialised for increased wound infliction and grip-and-tear feeding, whereas T. platyodon has a more elongate yet robust snout and larger teeth and may be more adapted for grip-and-shear feeding. These results suggest the existence of niche partitioning at higher trophic levels in Early Jurassic ichthyosaurians and have implications for future work on the taxonomy of this wastebasket genus, as well as for research into the ecology of other extinct megapredatory marine tetrapods.

onlinelibrary.wiley.com/doi/abs/10.1111/joa.13939


And we have a...bone-crushing felid, something I had previously only dreamed of.


A new large pantherine and a sabre-toothed cat (Mammalia, Carnivora, Felidae) from the late Miocene hominoid-bearing Khorat sand pits, Nakhon Ratchasima Province, northeastern Thailand

We describe two large predators from the hominoid-bearing Khorat sand pits, Nakhon Ratchasima Province, northeastern Thailand: a new genus of pantherine, Pachypanthera n. gen., represented by partial mandible and maxilla and an indeterminate sabre-toothed cat, represented by a fragment of upper canine. The morphological characters of Pachypanthera n. gen., notably the large and powerful canine, the great robustness of the mandibular body, the very deep fossa for the m. masseter, the zigzag HSB enamel pattern, indicate bone-cracking capacities. The genus is unique among Felidae as it has one of the most powerful and robust mandibles ever found. Moreover, it may be the oldest known pantherine, as other Asian pantherines are dated back to the early Pliocene. The taxa we report here are the only carnivorans known from the late Miocene of Thailand. Although the material is rather scarce, it brings new insights to the evolutionary history of Neogene mammals of Southeast Asia, in a geographic place which is partly “terra incognita.”

link.springer.com/article/10.1007/s00114-023-01867-4

[Supercommunist]

Random thought, but isn't tyrannosaurus a bit like the bull shark of theropods?

Like theropods, most sharks don't actually have terribly impressive bite force and rely on slicing teeth to kill prey.

However, bull sharks do actually have fairly powerful bites while also having devestating, flesh tearing bites.

In the past, I felt a lot of people overstated how blunt tyrannosaurus' teeth were compared to carnosaurs like gigantosaurus or allosaurus. It's possible bull sharks have a smaller gape as a consequence of their higher bite force but they don't seem to have a more difficult time ripping flesh than other sharks.

[theropod]

Aug 30, 2023 10:07:11 GMT 5 Supercommunist said:

Random thought, but isn't tyrannosaurus a bit like the bull shark of theropods?

Like theropods, most sharks don't actually have terribly impressive bite force and rely on slicing teeth to kill prey.

However, bull sharks do actually have fairly powerful bites while also having devestating, flesh tearing bites.

In the past, I felt a lot of people overstated how blunt tyrannosaurus' teeth were compared to carnosaurs like gigantosaurus or allosaurus. It's possible bull sharks have a smaller gape as a consequence of their higher bite force but they don't seem to have a more difficult time ripping flesh than other sharks.

I've handled bull shark jaws, and their teeth aren't any thicker or blunter than other macrophagous sharks.
I've not handled original T. rex teeth, but plenty of museum-quality replicas, and they definitely are much thicker and blunter, well in accordance with Abler's published findings. This isn't just a claim that's pulled out of thin air, it's a morphological fact. You can easily cut yourself on a bull shark tooth, but good luck trying the same on a T. rex tooth (not to mention the very rounded tooth cross-sections around 70% as thick as wide, which is unlike shark teeth with cutting adaptation and results in a very unfavourable edge geometry.) T. rex teeth do have edges and denticles, but they were clearly very bad at cutting. There's still many other good reasons to have these structures; an edge, even a blunt one, aids penetration by locally concentrating stresses, helping to start a tear in the material when penetrating it (that's why bodkin points or warhammer or polleaxe spikes are square in cross-section, not round). And theropod denticles are thought to have served to strengthen the tooth by stopping crack-propagation (a sort of analogue to mammalian Hunter-Schreger-bands?).

My impression is thus rather the opposite, that it is often forgotten how much blunter T. rex teeth are, not that it gets overstated. In many places there's still the narrative of the magical "better at everything" - bite. People want to believe T. rex has a bite with all the strengths of other theropods' bites, just way more powerful on top of that. But that's not how things normally work.
As for bull sharks, I'm not sure how good the quality of information demonstrating them to have considerably stronger bite forces than other macrophagous sharks even is. In the past there has been a bit of a problem with people just randomly mixing and matching incompatible methodologies when it came to shark bite force, so I'm sceptical of this claim until I've read the study.

[Supercommunist]

Aug 30, 2023 11:09:33 GMT 5 theropod said:

Aug 30, 2023 10:07:11 GMT 5 Supercommunist said:

Random thought, but isn't tyrannosaurus a bit like the bull shark of theropods?

Like theropods, most sharks don't actually have terribly impressive bite force and rely on slicing teeth to kill prey.

However, bull sharks do actually have fairly powerful bites while also having devestating, flesh tearing bites.

In the past, I felt a lot of people overstated how blunt tyrannosaurus' teeth were compared to carnosaurs like gigantosaurus or allosaurus. It's possible bull sharks have a smaller gape as a consequence of their higher bite force but they don't seem to have a more difficult time ripping flesh than other sharks.

I've handled bull shark jaws, and their teeth aren't any thicker or blunter than other macrophagous sharks.
I've not handled original T. rex teeth, but plenty of museum-quality replicas, and they definitely are much thicker and blunter, well in accordance with Abler's published findings. This isn't just a claim that's pulled out of thin air, it's a morphological fact. You can easily cut yourself on a bull shark tooth, but good luck trying the same on a T. rex tooth (not to mention the very rounded tooth cross-sections around 70% as thick as wide, which is unlike any macrophagous shark and results in a very unfavourable edge geometry.) T. rex teeth do have edges and denticles, but they were clearly very bad at cutting. There's still many other good reasons to have these structures; an edge, even a blunt one, aids penetration by locally concentrating stresses, helping to start a tear in the material when penetrating it (that's why bodkin points or warhammer or polleaxe spikes are square in cross-section, not round). And theropod denticles are thought to have served to strengthen the tooth by stopping crack-propagation (a sort of analogue to mammalian Hunter-Schreger-bands?).

My impression is thus rather the opposite, that it is often forgotten how much blunter T. rex teeth are, not that it gets overstated. In many places there's still the narrative of the magical "better at everything" - bite. People want to believe T. rex has a bite with all the strengths of other theropods' bites, just way more powerful on top of that. But that's not how things normally work.
As for bull sharks, I'm not sure how good the quality of information demonstrating them to have considerably stronger bite forces than other macrophagous sharks even is. In the past there has been a bit of a problem with people just randomly mixing and matching incompatible methodologies when it came to shark bite force, so I'm sceptical of this claim until I've read the study.

Greanted the bull shark and rex comparsion was a rather one but it seems inaccurate to say that tyrannosaurus' teeth were bad at cutting.

According to one paper, the evenly spaced denticles on theropod teeth make them more efficent at slicing than ziphodont teeth belonging to animals like dimetrodons or komodos.

www.researchgate.net/publication/280528592_Developmental_and_evolutionary_novelty_in_the_serrated_teeth_of_theropod_dinosaurs

One of the researchers even directly compared a dimetrodon's teeth to a tyrannosaurus and said the latter would have been better at cutting.

T. rex (and most other theropod) teeth were more efficient at slicing through their prey because the denticles are so regularly spaced, like a steak knife!

There is also the fact that a lot of modern animals that are adept at slicing flesh even though they don't have serrations on their teeth.

Crocodile monitors have notoriously nasty bites despite not having ziphodont teeth. Baboons, and african wild dogs are also capable of inflicting rapid tissue.

But most notably, I don't think pirannahs have proper cutting teeth either but they seem to be capable of ripping flesh just as effectively as sharks thanks to their sheer jaw power.

Given that tyrannosaurus actually did have the even denticle structure common amongst theropods its teeth should be much more efficent at cutting flesh than something like a komodo even if jaw strength was equalized. Likewise, a carnosaurs tooth would be better at cutting flesh on a newton per newton basis and their jaw gape would allow them to grip more flesh in a single bite but tyrannosaurus' sheer jaw strength might have been able to compensate for that.

As for the topic on bull shark bite force there seems to be a few studies that corroborate the idea that they have a high bite force compared to most sharks.

www.sciencedirect.com/science/article/abs/pii/S0944200612000670?via%3Dihub

[theropod]

One of the researchers even directly compared a dimetrodon's teeth to a tyrannosaurus and said the latter would have been better at cutting.

T. rex (and most other theropod) teeth were more efficient at slicing through their prey because the denticles are so regularly spaced, like a steak knife!

Indeed, though it’s unclear as to what she’s basing this on. The paper you cited makes no mention of regular spacing making the teeth more efficient at cutting (the word "regular" isn’t even in the paper). However it may well be that that is correct, although I would doubt that it makes a massive difference. The shape of individual denticles is likely far more important than how regularly spaced they are, especially if the difference is minor.

Be that as it may, that statement has to be understood as "all else being equal", of course. So a tyrannosaur with the same overall tooth geometry and sharpness might well be a more efficient slicer than a Dimetrodon (although as you say, even unserrated teeth can be decent at cutting, so it’s unlikely that a slight difference in how regular the denticles are spaced will make a world of a difference). But they do not have the same overall tooth geometry, and they definitely don’t have the same overall tooth geometry as sharks or some of the other

What I was referring to is this (from the only study I am aware of to actually experimentally test cutting performance in different teeth):

massiveTyrannosaurid teeth from the Cretaceous Judith River Formation bear rows of serrations that have thick, rounded enamel caps, gripping slots between neighboring serrations, thick enamel bodies inside the teeth underneath the gripping slots, and a root beneath each serration. In contrast, the carnivorous dinosaur Troodon has teeth with exposed pointed serrations, thin enamel, and possibly serration roots.

Serrations on the teeth of Troodon and the fossil shark Carcharodon, cut compliant materials in the same way as a serrated hacksaw blade. In contrast, the cutting action of tyrannosaurid teeth most closely resembles that of a dull smooth blade.

and:

From Abler, W.L. 1992. The serrated teeth of tyrannosaurid dinosaurs, and biting structures in other animals. Paleobiology 18 (2): 161–183.

In other words, there’s a big difference in terms of cutting capacity of the edges in a T. rex tooth and a shark tooth.

Even disregarding denticle function or edge sharpness, a tooth that is twice as thick can never be as efficient at cutting, for the same reason that a rapier blade can never be as efficient at cutting as a falchion; being thicker means they have a more obtuse edge geometry. Even honed to a razor edge, this edge geometry will always make them worse at cutting than more slender teeth. And that is assuming the edge is actually equally sharp, which reading Abler and if what I’ve handled is anything to go by, I don’t think it is, not by a long shot.

Given that tyrannosaurus actually did have the even denticle structure common amongst theropods its teeth should be much more efficent at cutting flesh even if jaw strength was equalized. Likewise, a carnosaurs tooth would be better at cutting flesh on a newton per newton basis and their jaw gape would allow them to grip more flesh in a single bite but tyrannosaurus' sheer jaw strength might have been able to compensate for that.

The issue here is that soft tissues and hard tissues react quite differently to the direct application of force. Soft tissues react to simple application of blunt force by deforming rather than ripping. Causing a certain amount of deformation will require the same force, irrespective of how powerful the bite or how sharp the teeth. So the most effective cutting dentition will be able to sever fibrous material with less total force than it takes to deform it. I’m pretty sure that with a butter knife (T. rex tooth analogue) I could not cut through a rope at all, even if I apply several times the force it takes me with a shark knife.

As for the topic on bull shark bite force there seems to be a few studies that corroborate the idea that they have a high bite force compared to ost sharks.

www.sciencedirect.com/science/article/abs/pii/S0944200612000670?via%3Dihub

Seems legit, thanks for the study. At first sight this does indeed seem conclusive.

[Infinity Blade]

Indeed, though it’s unclear as to what she’s basing this on. The paper you cited makes no mention of regular spacing making the teeth more efficient at cutting (the word "regular" isn’t even in the paper). However it may well be that that is correct, although I would doubt that it makes a massive difference. The shape of individual denticles is likely far more important than how regularly spaced they are, especially if the difference is minor.

Intuitively I do think it makes sense. If a tooth is being drawn across flesh, but the serrations aren't equal in size, one serration might make contact with the flesh, but the next, smaller one may not, and therefore will not contribute to cutting. Of course, that's not to say teeth with unevenly-sized denticles are bad at cutting; Dimetrodon and the likes are already at least one step ahead of any predator that lacks serrations in its teeth.

[Infinity Blade]

There’s a new paper that proposes that spinosaurids were actually more convergent with phytosaurs in craniodental anatomy than they are with crocodilians.

Some interesting ideas it proposes are that early-diverging spinosaurs (e.g. Suchomimus) were convergent with early-diverging dolichorostral phytosaurs, while late-diverging spinosaurs (e.g. Spinosaurus) were convergent with late-diverging brachyrostral phytosaurs. Also, it proposes that while Spinosaurus’ front teeth were still primarily for grasping prey, they may also have been used for crunching hard objects (like turtles or juvenile dinosaur bones).

actapalrom.geo-paleontologica.org/Online_first/Yun_Spinosaurs.pdf

[Infinity Blade]

Permian hypercarnivore suggests dental complexity among early amniotes

The oldest known complex terrestrial vertebrate community included hypercarnivorous varanopids, a successful clade of amniotes with wide geographic and temporal distributions. Little is known about their dentition and feeding behaviour, but with the unprecedented number of specimens of the varanopid Mesenosaurus from cave deposits in Oklahoma, we show that it exhibited serrations on the tooth crowns, and exceptionally rapid rates of development and reduced longevity relative to other terrestrial amniotes. In contrast, the coeval large apex predator Dimetrodon greatly increased dental longevity by increasing thickness and massiveness, whereas herbivores greatly reduced tooth replacement rates and increased dental longevity. Insectivores and omnivores represented the primitive condition and maintained modest replacement rates and longevity. The varied patterns of dental development among these early terrestrial amniotes reveal a hidden aspect of dental complexity in the emerging diverse amniote community, very soon after their initial appearance in the fossil record.

www.nature.com/articles/s41467-022-32621-5?error=cookies_not_supported&code=07372387-13d8-4dde-8b32-4400e976c40a

[Supercommunist]

For quite sometime I have been trying to figure out a good way to describe the sawing jaws motion some animals like mosasaurus were capable of. A guy in the mega beasts documentary (I know mega beast generally a bad source but I imagine the skull reconstruction themself was okay) describes the motion as "racheting" but I think reciprocating jaws would be a more apt term.


20:50



Coelophysis also apparently was capable of these jaw movements. Were most theropods capable of these jaw motions?

[Infinity Blade]

Comparative cranial biomechanics reveal that Late Cretaceous tyrannosaurids exerted relatively greater bite force than in early-diverging tyrannosauroids

Tyrannosaurus has been an exemplar organism in feeding biomechanical analyses. An adult Tyrannosaurus could exert a bone-splintering bite force, through expanded jaw muscles and a robust skull and teeth. While feeding function of adult Tyrannosaurus has been thoroughly studied, such analyses have yet to expand to other tyrannosauroids, especially early-diverging tyrannosauroids (Dilong, Proceratosaurus, and Yutyrannus). In our analysis, we broadly assessed the cranial and feeding performance of tyrannosauroids at varying body sizes. Our sample size included small (Proceratosaurus and Dilong), medium-sized (Teratophoneus), and large (Tarbosaurus, Daspletosaurus, Gorgosaurus, and Yutyrannus) tyrannosauroids, and incorporation of tyrannosaurines at different ontogenetic stages (small juvenile Tarbosaurus, Raptorex, and mid-sized juvenile Tyrannosaurus). We used jaw muscle force calculations and finite element analysis to comprehend the cranial performance of our tyrannosauroids. Scaled subtemporal fenestrae areas and calculated jaw muscle forces show that broad-skulled tyrannosaurines (Tyrannosaurus, Daspletosaurus, juvenile Tyrannosaurus, and Raptorex) exhibited higher jaw muscle forces than other similarly sized tyrannosauroids (Gorgosaurus, Yutyrannus, and Proceratosaurus). The large proceratosaurid Yutyrannus exhibited lower cranial stress than most adult tyrannosaurids. This suggests that cranial structural adaptations of large tyrannosaurids maintained adequate safety factors at greater bite force, but their robust crania did not notably decrease bone stress. Similarly, juvenile tyrannosaurines experienced greater cranial stress than similarly-sized earlier tyrannosauroids, consistent with greater adductor muscle forces in the juveniles, and with crania no more robust than in their small adult predecessors. As adult tyrannosauroid body size increased, so too did relative jaw muscle forces manifested even in juveniles of giant adults.

anatomypubs.onlinelibrary.wiley.com/doi/full/10.1002/ar.25326

(I’ll italicize the genus names later)

[Infinity Blade]

Estimation of mechanical advantage suggests that Edestus heinrichi has a two gear system that operates the jaws. The QMA and QMV muscles appear to have similar MA values (0.33–0.20 for proximal-distal teeth) when the mouth is closed. However, when the mouth is maximally opened, MA increases (0.46–0.28 for the proximal-distal teeth) transferring more force for slicing through prey. Greater force can be transmitted through the QMP muscle (0.52–0.32 MA for proximal-distal teeth) regardless of the state of mouth opening. The QMP (425–265 N proximal-distal) and QMV (375–234 N) have better leverage for transmitting force to the teeth compared to the QMA (134–83 N). Perhaps the QMA functions to close the mouth faster while the QMP transmits more bite force. QMV appears to function during ventilation in modern sharks. Total estimated force output for all muscle divisions is estimated at 1907 N, half that estimated for Helicoprion, which only has a single 23 cm diameter tooth whorl (Ramsay et al., 2015).

anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.24046

[Supercommunist]

Fastest death roll I ever seen. Wonder what kind of damage an eel could do if it grabbed a person and span like a twister?

www.reddit.com/r/HardcoreNature/comments/16x1ai2/eel_swallowing_a_bobbit_worm/