Functional Morphology of Animal Feeding Apparata

[Supercommunist]

Found a crazy account on a subreddit about police brutality.

Second nastiest human bite I have ever seen. Beaten only by the bath salts guy. Very NSFW.

Man bites a chunk of flesh from a police officers head,

www.mypanhandle.com/news/local-news/holmes-county/graphic-florida-man-bites-chunk-out-of-deputys-head-sheriff-says/

Generally speaking, most self defense/martial artists deride the human bite as a pretty subpar. At worst it could mangle something soft, like a nose, lip, or ear and maybe a finger but often time those wounds don't actually debilitate and would just escalate the fight and just encourage the other guy to brutalize you if they are the better fighter. They had some good points but this account does show that a human bite can be super gnarly.

[Infinity Blade]

Of course it was Florida man…

But on a serious note, one half of me isn’t too surprised by this level of damage.

[Shri devi]

From the Meraxes gigas description:

The paroccipital process is very long and more ventrally angled than in Acrocanthosaurus.

Were members of Giganotosaurini still capable of powerful ventroflexion like Allosaurus?

[Infinity Blade]

Comparing cranial biomechanics between Barbourofelis fricki and Smilodon fatalis

Saber-tooths, extinct apex predators with long and blade-like upper canines, have appeared iteratively at least five times in the evolutionary history of vertebrates. Although saber-tooths exhibit a relatively diverse range of morphologies, it is widely accepted that all killed their prey using the same predatory behavior. In this study, we CT-scanned the skull of Barbourofelis fricki and compared its cranial mechanics using finite element analysis (FEA) with that of Smilodon fatalis. Our aim was to investigate potential variations in killing behavior between two dirk-toothed sabretooths from the Miocene and Pleistocene of North America. The study revealed that B. fricki had a stoutly-built skull capable of withstanding stress in various prey-killing scenarios, while the skull of S. fatalis appeared less optimized for supporting stress, which highlights the highly derived saber–tooth morphology of the former. The results may indicate that B. fricki was more of a generalist in prey-killing compared to S. fatalis, which experiences lower stresses under stabbing loads. We hypothesize that morphological specialization in saber-tooths does not necessarily indicate ecological specialization. Our results support the notion that morphological convergence among saber-toothed cats may obscure differences in hunting strategies employed to dispatch their prey. Our findings challenge the assumption of the universally assumed canine-shear biting as the preykilling behavior of all saber-toothed cats. However, further research involving a wider range of dirk and scimitar-toothed forms could provide additional insights into the diversity of cranial biomechanics within this fascinating group of extinct mammalian predators.

pure-oai.bham.ac.uk/ws/portalfiles/portal/224322591/ar.25451.pdf

[Supercommunist]

I recall reading an article that claimed wolves typically kill each other with a single bite to the skull. This observation does not line up with the videos of wolf intraspecific conflict/predation on dogs/coyotes I have seen.

Personally I suspect that there is an opposite of a survivorship bias going. I don't think wolves are often able to kill each other with a single bite, I suspect that wolves usually survive attacks from conspecifics and the ones that usually end up dying are the unlucky ones that got killed by a lucky bite to the head.

[Infinity Blade]

Mandibular force profiles of Alioramini (Theropoda: Tyrannosauridae) with implications for palaeoecology of this unique lineage of tyrannosaurid dinosaurs

Alioramin theropods, a unique lineage within the clade Tyrannosauridae, are characterized by relatively diminutive size and longirostrine skull with increased tooth counts. Based on this unusual morphology, it has been suggested that alioramins had a unique ecological niche for tyrannosaurids, primarily hunting small prey items. However, there has been no quantitative evidence suggested for this claim. In this work, mandibular force profiles of the alioramins Alioramus altai and Qianzhousaurus sinensis are examined. The bending strength of the symphyseal region is found to be stronger than the middentary in both taxa, as in other tyrannosaurids. However, the relative mandibular force at the symphyseal region in alioramins is significantly higher, suggesting this region went through significantly less torsional stresses compared to non-alioramin tyrannosaurids. This may also suggest they used shearing, slashing bites more frequently in hunting and feeding than other tyrannosaurids. Additionally, the bending force at the middentary, which is a valid proxy for a bite force in theropods, of alioramins is found to be both relatively and absolutely lower than other tyrannosaurids, or even non-tyrannosaurid theropods of similar mandibular length. Such results strongly imply alioramins were unsuited for delivering powerful bites and enduring high torsional loads, and are consistent with the previous hypothesis that alioramins mainly fed on small prey that did not require a strong bite force or mandibular symphysis capable of resisting high torsional stresses to capture and manipulating.

It's interesting that the maximum prey body mass of both alioramins is still estimated to be significantly greater than their own, something I suspected to be true (although, the supplementary info of the paper this one cites implicitly admits that these equations can be underestimates of actual maximum prey size).

[Supercommunist]

In regards to smilodon, while I do think it was a formidable predator and fighter, I think its big game hunting abilities was seriously overestimated and it would actually have a harder time punching way above its weight than a similar sized cat with more standard dentition (though it would have been better equipped to kill typical upper end sized prey like bison).

So the most direct evidence would be an isotope study that found smilodon had a strong preference for smaller, and probably relatively slow prey like ground sloths.

An atypical preference for small and medium-size prey for the predator S. populator, and a mainly herbivorous diet with a slight amount of meat for the bear A. wingei is also discussed.

www.tandfonline.com/doi/abs/10.1080/08912963.2021.1933468?journalCode=ghbi20

In fairness to smilodon, lions also have a strong preference for warthogs despite being smaller than their predicted prefered prey mean mass because they are small enough to be easily restrained (relatively anyway) while also being slower than lions (though still fast). Therefore it's not surprising that smilodon would have loved to eat smaller ground sloths if they were available.

Still, I think their sabre teeth presents problems. While people overstate how delicate they are, they are still more prone to damage than standard cat canines, and macropredatory cats themselves often suffer canine breakage fairly early in life. Males suffer higher a higher rate of tooth breakage than females.

At an estimated age of four years, five out of seven males had one broken canine,
and by the estimated age of five to eight years, all four males had at least one
broken canine. Females appeared less prone to tooth breakage as only one out of
six females between the estimated ages of two to seven years, had a broken
canine tip.

Tooth breakage, especially of canine teeth, is common in extant carnivores
(Van Valkenburgh, 1988) but has been recorded at a much higher frequency
among Pleistocene carnivores (Van Valkenburgh & Hertel, 1993). There is a 25%
likelihood of extant carnivores breaking a tooth during their life, and it is a
function of age, increased feeding pressure, and eating meat that includes bones
(Van Valkenburgh, 1988). Male leopards in Namibia showed a higher frequency
of broken canines than females. Both sexes had the same feeding habits in terms
of prey species, but males consumed more food than females (unpublished data).
The discrepancy in fractured canines may be explained by the fact that the
smaller females with smaller teeth, compared to males, exhibit greater precision
when feeding and are less prone to injurious contact with bones (see Van
Valkenburgh, 1996). The fact that enamel flaking is more common in males
supports the suggestion of repeated contact between anterior teeth and bone.
Decay of enamel layers may weaken teeth (Rensberger, 1995) and augment
fractures.

onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2028.1997.068-89068.x

^There is a neat chart in the full study that sums up the kind of teeth wear leopards suffer based on their ages. The study notes that even wear becomes apparent on the canines by age 3.

A graph in this study states that about 10 percent of amur tigers between the ages of 4 to 7 had a broken canine. Granted the study also suggests that people overestimate how bad a broken canine is, but smilodon does seem like it would be more reliant on having quality teeth.

zslpublications.onlinelibrary.wiley.com/doi/abs/10.1111/j.1469-7998.2011.00819.x

So yeah, I suspect that in order to prevent their teeth from being smashed too early in life smilodon would have usually limited itself to prey that modern lions and tigers could usually subdue as well. The smilodon would have been better at restraining large bovines and killing them quickly but I doubt they would have been the rhino and sub adult mammoth killers they are often potrayed as because trying to bite such a large thrashing animal would have been hard on their sabre teeth,

[Infinity Blade]

Jul 14, 2024 0:06:29 GMT 5 Supercommunist said:

In regards to smilodon, while I do think it was a formidable predator and fighter, I think its big game hunting abilities was seriously overestimated and it would actually have a harder time punching way above its weight than a similar sized cat with more standard dentition (though it would have been better equipped to kill typical upper end sized prey like bison).

So the most direct evidence would be an isotope study that found smilodon had a strong preference for smaller, and probably relatively slow prey like ground sloths.

An atypical preference for small and medium-size prey for the predator S. populator, and a mainly herbivorous diet with a slight amount of meat for the bear A. wingei is also discussed.

www.tandfonline.com/doi/abs/10.1080/08912963.2021.1933468?journalCode=ghbi20

In fairness to smilodon, lions also have a strong preference for warthogs despite being smaller than their predicted prefered prey mean mass because they are small enough to be easily restrained (relatively anyway) while also being slower than lions (though still fast). Therefore it's not surprising that smilodon would have loved to eat smaller ground sloths if they were available.

Still, I think their sabre teeth presents problems. While people overstate how delicate they are, they are still more prone to damage than standard cat canines, and macropredatory cats themselves often suffer canine breakage fairly early in life. Males suffer higher a higher rate of tooth breakage than females.

At an estimated age of four years, five out of seven males had one broken canine,
and by the estimated age of five to eight years, all four males had at least one
broken canine. Females appeared less prone to tooth breakage as only one out of
six females between the estimated ages of two to seven years, had a broken
canine tip.

Tooth breakage, especially of canine teeth, is common in extant carnivores
(Van Valkenburgh, 1988) but has been recorded at a much higher frequency
among Pleistocene carnivores (Van Valkenburgh & Hertel, 1993). There is a 25%
likelihood of extant carnivores breaking a tooth during their life, and it is a
function of age, increased feeding pressure, and eating meat that includes bones
(Van Valkenburgh, 1988). Male leopards in Namibia showed a higher frequency
of broken canines than females. Both sexes had the same feeding habits in terms
of prey species, but males consumed more food than females (unpublished data).
The discrepancy in fractured canines may be explained by the fact that the
smaller females with smaller teeth, compared to males, exhibit greater precision
when feeding and are less prone to injurious contact with bones (see Van
Valkenburgh, 1996). The fact that enamel flaking is more common in males
supports the suggestion of repeated contact between anterior teeth and bone.
Decay of enamel layers may weaken teeth (Rensberger, 1995) and augment
fractures.

onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2028.1997.068-89068.x

^There is a neat chart in the full study that sums up the kind of teeth wear leopards suffer based on their ages. The study notes that even wear becomes apparent on the canines by age 3.

A graph in this study states that about 10 percent of amur tigers between the ages of 4 to 7 had a broken canine. Granted the study also suggests that people overestimate how bad a broken canine is, but smilodon does seem like it would be more reliant on having quality teeth.

zslpublications.onlinelibrary.wiley.com/doi/abs/10.1111/j.1469-7998.2011.00819.x

So yeah, I suspect that in order to prevent their teeth from being smashed too early in life smilodon would have usually limited itself to prey that modern lions and tigers could usually subdue as well. The smilodon would have been better at restraining large bovines and killing them quickly but I doubt they would have been the rhino and sub adult mammoth killers they are often potrayed as because trying to bite such a large thrashing animal would have been hard on their sabre teeth,

There was a book chapter explaining that while scimitar-toothed cats had a "default bite" (using only the incisors) to fall back on if something was too large for their canine bite, dirk-toothed cats didn't have one. Ergo, anything that was too wide for their canine bite was too big to be preyed on, period. Modern conical-toothed cats will basically eat their prey to death like canids or hyaenids if they're too big for a suffocating throat bite or skull bite, and it's concluded that lions (given enough time and enough lions) are able to take prey out of reach of what a Smilodon could hunt for this reason.


www.google.com/books/edition/The_Other_Saber_tooths/2GjhrKO9y74C?hl=en&gbpv=1&bsq=default%20bite

[Supercommunist]

I find it a bit weird how cats like homotherium are call scimitar teethed while Smilodon with longer teeth are called dirk toothed.

[Infinity Blade]

High-resolution CT-scan data reveals the tooth replacement pattern of the Late Jurassic tyrannosauroid Guanlong wucaii (Dinosauria, Theropoda)

The Tyrannosauridae, which is characterized by specialized pachydont dentition and putative bone-cracking predatory strategies, is one of the most extensively studied theropod lineages. Although tooth replacement patterns, crucial for understanding feeding behaviors, have been thoroughly studied in this group, studies on non-tyrannosaurid tyrannosauroids are relatively scarce. This study utilizes high-resolution CT data to investigate the tooth replacement pattern in two specimens of Guanlong wucaii, a Late Jurassic tyrannosauroid, and provides insights into the evolution of tooth replacement across Tyrannosauroidea. Second-generation replacement teeth, a rarity observed mainly in giant predatory theropods (e.g. some tyrannosaurids), were detected in the dentary dentition of the juvenile Guanlong. Zahnreihen reconstructions display a consistent cephalad alternating tooth replacement pattern in the maxilla and the dentary of both of the examined individuals, with Z-spacing values exceeding 2.0. As Guanlong grows, the Z-spacing value in the maxillary dentition increases, resembling the ontogenetic changes documented in the Tyrannosauridae. Additionally, like Tarbosaurus, Guanlong also displays a discontinuity between the tooth replacement waves at the premaxilla-maxilla boundary. This study thus demonstrates that some tyrannosaurid-like tooth replacement patterns were acquired before the origin of the Tyrannosauridae.

www.vertpala.ac.cn/EN/10.19615/j.cnki.2096-9899.240715

[Supercommunist]

So, I heard that current consensus is that Masiakasaurus was a fossorial hunter and that there is no evidence that it was adapted to eating fish.

Just curious, could its weird teeth be an effective tool for catching fish, or was it poorly designed for that task?

[Infinity Blade]

Jul 29, 2024 8:44:07 GMT 5 Supercommunist said:

So, I heard that current consensus is that Masiakasaurus was a fossorial hunter and that there is no evidence that it was adapted to eating fish.

Just curious, could its weird teeth be an effective tool for catching fish, or was it poorly designed for that task?

For whatever it's worth, Prehistoric Planet depicts Masiakasaurus as more of a hunter of small terrestrial vertebrates (which, yes, it's just a documentary, but it does reflect what the scientific advisors think of its paleobiology), but I don't think fish are necessarily off the table, just maybe not what the teeth were primarily for.

Interestingly, tyrannosaurids also had some procumbent dentary teeth (albeit to a lesser extent), and it's believed that this allowed them to bite flesh and bone off a body part that's gently curved (like the rib cage or abdomen). Since it's even more pronounced in Masiakasaurus, I think logically this would also apply to it.

Procumbent mesial teeth are common in piscivorous animals including crocodiles, fish, and pterosaurs (Xing et al., 2013b). A forward-projecting mesial tooth arrangement seems to be adapted for the prehension of small prey such as invertebrates and small vertebrates such as fish (Carrano et al., 2002). In coelophysoids and spinosaurids, procumbent maxillary teeth result from the sigmoid ventral margin of the maxilla and are suitable for gripping small to moderate-sized prey transversally through slashing bites (Charig and Milner, 1997; Therrien et al., 2005). The sigmoid margin of the upper jaw, present in many crocodylomorphs, would also have enhanced the ability for holding prey and/or tearing their flesh (Russell and Wu, 1997). Bakker and colleagues (1988) suggested that the mesialmost procumbent dentary teeth of tyrannosaurids allowed to bite a chunk of bone and flesh off a prey’s body part that was gently curved such as the rib-cage and abdominal wall when the head was moving forward.

palaeo-electronica.org/content/2019/2806-dental-features-in-theropods?fbclid=IwAR1RRVN27zpDnJKZFdYKM9HTJOsP5Z_ZTmprSiFenfljC6P49piirTv8gCM

[Supercommunist]

Jul 30, 2024 3:17:29 GMT 5 Infinity Blade said:

Jul 29, 2024 8:44:07 GMT 5 Supercommunist said:

So, I heard that current consensus is that Masiakasaurus was a fossorial hunter and that there is no evidence that it was adapted to eating fish.

Just curious, could its weird teeth be an effective tool for catching fish, or was it poorly designed for that task?

For whatever it's worth, Prehistoric Planet depicts Masiakasaurus as more of a hunter of small terrestrial vertebrates (which, yes, it's just a documentary, but it does reflect what the scientific advisors think of its paleobiology), but I don't think fish are necessarily off the table, just maybe not what the teeth were primarily for.

Interestingly, tyrannosaurids also had some procumbent dentary teeth (albeit to a lesser extent), and it's believed that this allowed them to bite flesh and bone off a body part that's gently curved (like the rib cage or abdomen). Since it's even more pronounced in Masiakasaurus, I think logically this would also apply to it.

Procumbent mesial teeth are common in piscivorous animals including crocodiles, fish, and pterosaurs (Xing et al., 2013b). A forward-projecting mesial tooth arrangement seems to be adapted for the prehension of small prey such as invertebrates and small vertebrates such as fish (Carrano et al., 2002). In coelophysoids and spinosaurids, procumbent maxillary teeth result from the sigmoid ventral margin of the maxilla and are suitable for gripping small to moderate-sized prey transversally through slashing bites (Charig and Milner, 1997; Therrien et al., 2005). The sigmoid margin of the upper jaw, present in many crocodylomorphs, would also have enhanced the ability for holding prey and/or tearing their flesh (Russell and Wu, 1997). Bakker and colleagues (1988) suggested that the mesialmost procumbent dentary teeth of tyrannosaurids allowed to bite a chunk of bone and flesh off a prey’s body part that was gently curved such as the rib-cage and abdominal wall when the head was moving forward.

palaeo-electronica.org/content/2019/2806-dental-features-in-theropods?fbclid=IwAR1RRVN27zpDnJKZFdYKM9HTJOsP5Z_ZTmprSiFenfljC6P49piirTv8gCM

You know, a dinosaur with a spinosaurid like jaw and Masiakasaurus style seems like the perfect build for a small, terrestrial prey specialist.

[Infinity Blade]

Apparently great white sharks attack Cape fur seals with lateral snaps of their anterolateral teeth rather than just their anterior teeth. Not only is this the part of the jaw where their jaws are the strongest, but this also produces a larger cutting wound.

The upper dentition of all modern white sharks features reversed intermediate teeth. If these teeth have a function, they cannot be considered in isolation but in conjunction with the teeth that £ank it. The teeth of adolescent and adult white sharks are unique among lamnoids in having coarsely serrated crowns and in having lateral teeth that are proportionately broader than those of any other lamnoid (Bass et al., 1975). The first and second anterior teeth (A1 and A2) of white sharks are erect and nearly symmetrical, while the lateral teeth (L1^L5) become progressively slanted toward the jaw corner (Bass et al., 1975). The reversed intermediate tooth (I) of white sharks creates a significantly larger interspace measurement between it and the first lateral tooth (L1) than between any other two teeth of the upper jaw. As a consequence, the longest cutting edges of these teeth face one another. Such an arrangement, combined with the curved cutting edge of I, would produce the largest puncture wounds at this site on either side of the jaw. The large space between I and L1 is buttressed by the intermediate bar and occurs at the point of maximum curvature of the upper jaw, which
may make this region the strongest part of the upper jaw. If the importance of incapacitating pinniped prey in the initial strike is as vital to the predatory success of white sharks as the results presented here suggest, and the lateral snap (LS) behaviour is a typical mode of prey capture employed by white sharks, then the functional significance of the reversed intermediate teeth is clear.

www.cambridge.org/core/journals/journal-of-the-marine-biological-association-of-the-united-kingdom/article/abs/predatory-behaviour-of-white-sharks-carcharodon-carcharias-at-seal-island-south-africa/0B567A5205A431DC464BAF1686065371

[dinosauria101]

Maybe an unusual request, but does anyone know of any studies on the mechanisms of horsefly or deerfly mouthparts? I would look for one myself but I get really grossed out by the far too common images on the internet of horseflies and deerflies biting people.