Functional Morphology of Animal Feeding Apparata

[theropod]

Hmm while I think it stands to reason that they tend to generally produce underestimates relative to in vivo measurements, I think not all 3D bite force models are equal. It depends on the exact method and assumptions made during modelling and simulation, e.g. about pennation angle or osteologically unconstrained muscles. E.g. for crocodiles the estimates are conservative because of the very large and efficient M. pterygoideus being underestimated. On the other hand, Bates and Falkingham’s multibody dynamics modelling accounted for pennation angle (even too much: royalsocietypublishing.org/doi/full/10.1098/rsbl.2018.0160) and iirc also figured the peak bite forces (although those are higher than the estimates commonly cited from them).
As of my understanding using FEA used along with the dry skull method only serves to validate or constrain the upper bound of the estimate, by checking whether the skull could withstand it, but cannot add something to the bite force estimate in and of itself.

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Interesting study on determining bite force in primates from histological tooth sections.

onlinelibrary.wiley.com/doi/pdf/10.1002/ajpa.24003?casa_token=dGAZlWqHbGgAAAAA:bS_Mxx8fBBowEugDSOyBLcJvPUBi-0A0FJb7caq1y0v9uF0tlEmBzWBZREzjNfxYFhpil6nbgOXnDso


Another study with an interesting passage that reminds me of a discussion I had here a year ago.

When comparing our average bite force values with the estimates of Wroe et al. (2010), our estimates fall above their values for female G. gorilla (2,773 N vs. 1,723 N), Au. boisei (3,717 vs. 2,161 N), female P. pygmaeus (1,931 vs. 1,031 N), Au. africanus (1,682 vs. 831 N), and female P. troglodytes (1,632 vs. 1,511 N) but our bite force estimates fall below their average estimated bite force for female H. sapiens (870 vs. 1,317 N). There are several reasons why our results may differ. First, Wroe et al.’s estimates are based on only one female individual per species and thus may under represent average bite forces. Additionally, because Wroe et al. used human CFs to estimate muscle PCSA in anthropoids, they likely underestimate nonhuman anthropoid muscle PCSAs and subsequently, muscle forces (Taylor and Vinyard, 2013). On the other hand, Wroe et al. (2010) estimated H. sapiens bite force from a San hunter-gatherer, who may generate higher bite forces than our late agricultural/early industrial modern human sample that likely consumed a highly processed diet. Additionally, they estimate three-dimensional bite forces, whereas this study’s moment arms are solely in the sagittal plane and 3D bite force estimates may be more accurate than 2D estimates. Finally, Wroe et al. represented muscles as multiple force vectors, which may more accurately represent muscles with complex attachments.

onlinelibrary.wiley.com/doi/pdf/10.1002/ajpa.22296?casa_token=VtbPpbin0RYAAAAA:PGCeGPRjYdvEsR3g5ZDo4wxxuCIR862fNZzvB8vEWHCQIUrY5_oj8tWiMhePZUBDB3x8j7tZhm3wrC0

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Mechanical compensation in the evolution of the early hominin feeding apparatus

Australopiths, a group of hominins from the Plio-Pleistocene of Africa, are characterized by derived traits in their crania hypothesized to strengthen the facial skeleton against feeding loads and increase the efficiency of bite force production. The crania of robust australopiths are further thought to be stronger and more efficient than those of gracile australopiths. Results of prior mechanical analyses have been broadly consistent with this hypothesis, but here we show that the predictions of the hypothesis with respect to mechanical strength are not met: some gracile australopith crania are as strong as that of a robust australopith, and the strength of gracile australopith crania overlaps substantially with that of chimpanzee crania. We hypothesize that the evolution of cranial traits that increased the efficiency of bite force production in australopiths may have simultaneously weakened the face, leading to the compensatory evolution of additional traits that reinforced the facial skeleton. The evolution of facial form in early hominins can therefore be thought of as an interplay between the need to increase the efficiency of bite force production and the need to maintain the structural integrity of the face.

royalsocietypublishing.org/doi/10.1098/rspb.2022.0711#.Yq8aEW_pdH8.twitter

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Apatosaurines had a unique feeding mechanism.

Dental complexes of sauropod dinosaurs have been studied in members of Diplodocoidea and Macronaria. However, the disparity among the number of replacement teeth between the premaxilla, maxilla, and dentary of apatosaurine sauropods has yet to be fully investigated. TATE-099, a nearly complete and associated apatosaurine skull and dental complexes from the upper Morrison Formation (Upper Jurassic) at Como Bluff, Wyoming, contains cranial characters consistent with Apatosaurus sp. Unerupted dental complexes of the right premaxilla, maxilla, and dentary were imaged and digitally reconstructed using computed tomography (CT). Results indicate four premaxillary alveolar positions each with 5-7 unerupted replacement teeth, 10 maxillary alveolar positions each with 3-5 unerupted replacement teeth, and 10 dentary alveolar positions each with only 1-2 unerupted replacement teeth. The capacity of replacement teeth in TATE-099 is higher than reported in the genus Diplodocus and consistent with data from previous studies on niche partitioning among coeval Morrison Formation sauropods. Disparity among the capacity of dental complexes of TATE-099 further suggests novel feeding mechanics in apatosaurines. CT data also support a new hypothesis of tooth replacement in diplodocids, where entire rows of teeth are replaced as a single unit, rather than individually. The high-capacity of replacement teeth in the premaxilla is only known to be succeeded by one taxon (Nigersaurus) and suggests frequent wear of the premaxillary teeth. However, considerably fewer replacement teeth in the dentary of TATE-099 suggests less-frequent. These results offer insight into the feeding mechanisms and disparity of sauropods within Flagellicaudata.

palaeo-electronica.org/content/2022/3653-apatosaurine-feeding-mechanism

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Estimating bite force in extinct dinosaurs using phylogenetically predicted physiological cross-sectional areas of jaw adductor muscles

I present a Bayesian phylogenetic predictive modelling (PPM) framework that allows the prediction of muscle parameters (physiological cross-sectional area, APhys) in extinct archosaurs from skull width (WSk) and phylogeny. This approach is robust to phylogenetic uncertainty and highly versatile given its ability to base predictions on simple, readily available predictor variables. The PPM presented here has high prediction accuracy (up to 95%), with downstream biomechanical modelling yielding bite force estimates that are in line with previous estimates based on muscle parameters from reconstructed muscles. This approach does not replace muscle reconstructions but one that provides a powerful means to predict APhys from skull geometry and phylogeny to the same level of accuracy as that measured from reconstructed muscles in species for which soft tissue data are unavailable or difficult to obtain.

peerj.com/articles/13731/#table-1

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This new study finds that large carnivorous archosaurs tend to have keyhole or elliptical shaped orbits, while circular orbits are the norm. Biomechanical modeling shows that this is an adaptation to dissipate skull stress while biting.

www.nature.com/articles/s42003-022-03706-0

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Air Breathing and Suction Feeding Kinematics in the West African Lungfish, Protopterus annectens

Research on the water-to-land transition tends to focus on the locomotor changes necessary for terrestriality. However, the evolution from water breathing to air breathing was also a necessary precursor to the invasion of land. Air is approximately 1000 times less dense and 50 times less viscous, and contains hundreds of times more oxygen than water. However, unlike the transition to terrestrial locomotion, breathing air does not require body weight support, so the evolution of air breathing may have necessitated smaller changes to morphology and function. We used X-ray reconstruction of moving morphology to compare the cranial kinematics of aquatic buccal pumping, such as that seen in suction feeding, with the aerial buccal pumping required for lung ventilation in the West African lungfish (Protopterus annectens). During buccal pumping behaviors, the cranial bones and associated soft tissues act as valves and pumps, and the sequence of their motions controls the pattern of fluid flow. Both behaviors are characterized by an anterior-to-posterior wave of expansion and an anterior-to-posterior wave of compression. We found that the pectoral girdle and cranial rib rotate consistently during air breathing and suction feeding, and that the muscle between them shortens during buccal expansion. Overall, we conclude that the major cranial bones maintain the same basic functions (i.e., acting as valves or pumps, or transmitting power) across aquatic and aerial buccal pumping. The cranial morphology that enables aquatic buccal pumping is well suited to perform air breathing and accommodates the physical differences between air and water.

academic.oup.com/icb/advance-article/doi/10.1093/icb/icac109/6633662?login=false

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Torn limb from limb: the ethology of prey-processing in Tasmanian devils (Sarcophilus harrisii)

The success of carnivorous mammals is determined not only by their ability to locate and kill prey, but also their efficiency at consuming it. Breaking large prey into small pieces is challenging due to the strong and tough materials that make up a carcass (e.g. hide, muscle, and bone). Carnivores therefore require a diverse suite of prey-processing behaviours to utilise their catch. Tasmanian devils are Australia’s only large marsupial scavengers and have the ability to consume almost all of a carcass. To determine how they do this we analysed 5.5 hours of footage from 21 captive and wild devils feeding at carcasses. We documented 6320 bouts of 12 distinct prey-processing behaviours, performed at frequencies that varied throughout feeds and between groups. The time point in the feed influenced the types of behaviours used. This is likely due to changing prey size, as different techniques appear better suited to handling whole
carcasses or large pieces (pulling and pinning) or smaller pieces (holding and manipulating). Group size impacted the frequency of social pulling behaviours, which increased with the number of animals. Our findings highlight the range of prey-processing behaviours performed by scavenging devils when handling, breaking down, and consuming a carcass. The devils’ repertoire shares similarities with large carnivores that handle and consume whole carcasses as well as small carnivores that are adept in grasping and handling smaller prey.

www.researchgate.net/profile/David-Hocking-2/publication/353770070_Torn_limb_from_limb_The_ethology_of_prey-processing_in_Tasmanian_devils_Sarcophilus_harrisii/links/6181f4e3eef53e51e1202710/Torn-limb-from-limb-The-ethology-of-prey-processing-in-Tasmanian-devils-Sarcophilus-harrisii.pdf

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Jaw Mechanics in Macrophagous Lamniform Sharks and Their Evolutionary and Functional Implications

Jaw mechanics of lamniform sharks were examined three-dimensionally to analyze the variability in jaw shape and the evolution of the jaw system based on the extant macrophagous species. Three-dimensional lever analysis was applied to lamniform jaws to calculate bite force at each tooth relative to maximum input force from jaw adductor muscles for interspecific comparison of efficiency in lamniform jaws. When total input force from the jaw adductor muscles on both working and balancing sides of the skull is considered, input force varies along the jaw because the contribution by balancing side muscles is not constant. The phylogenetically basal-most species, Mitsukurina owstoni, has the least efficient jaws due to posteriorly positioned jaw adductor muscles. Our study shows that the higher efficiency of jaws is regarded as apomorphic in lamniform phylogeny owing to the anterior extension of jaw adductor muscles relative to M. owstoni and a relative decrease in jaw length in relation to width seen in some species, both of which increase leverage. Differences in the efficiency of jaws among derived genera or species are due to the morphology of their jaws. The relationship between calculated bite force relative to maximum input force and tooth morphology indicates low relative bite forces being exerted at anteriorly located, narrow, piercing teeth, whereas high relative bite forces at posteriorly located, broad, cutting, or crushing-type teeth. As a result, the biting pressure during predation is maintained throughout the tooth series.

anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.25071

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Gavialis gangeticus has often been used as an eco-analogue of the extinct choristodere Champsosaurus in terms of diet and feeding behaviour. Both reptiles are specialised for lateral neck flexion but in different ways: in Gavialis, lateral flexion mainly occurs in the anterior neck, with a slight rotation about the craniocaudal axis through the neck; in Champsosaurus, horizontal lateral flexion is estimated to have occurred through the middle to the posterior part of the neck, with movement in the anterior neck constrained by the cordiform skull that extends posteriorly above the beginning of the neck.

Champsosaurus may have used its slender snout to grab fish from shoals using lateral sweeping motions of the neck, but inertial feeding is unlikely to have occurred and intraoral transport is likely to have combined a fleshy tongue working against the craniocaudally aligned palatal dentition.

The choristodere Simoedosaurus may have had a wider range of neck movements with both dorsal and lateral components, a pattern broadly similar to that of small short-snouted crocodilians (e.g. Caiman latirostris). A capacity for dorsiflexion of the neck may have allowed Simoedosaurus to grab prey above the water. Where the two choristoderes occurred in the same place, they may have divided their niche by prey type.

...the necks of Champsosaurus and Simoedosaurus show clear differences in the estimated range of lateral and dorsiflexion, differences that might correlate with their feeding behaviour. On the other hand, the dorsiflexor moment arms (Index 2) are similar in Champsosaurus and Simoedosarus (Figure 7b), and these values are greater than those of Gavialis gangeticus. This result suggests that the necks of the two choristoderes have a greater potential to raise the head powerfully against gravity compared to G. gangeticus, and these reptiles may have been better at holding larger struggling prey in their jaws.

onlinelibrary.wiley.com/doi/abs/10.1111/joa.13600

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Although the strength of the symphysis varies among species, all felids possess a dorsoventrally and labiolingually strong symphyseal region (Zx/L and Zy/L respectively) compared to canids and hyaenids (see below). This adaptation reflects the powerful canine bite used by felids to kill their prey (Ewer, 1973). Because felids are generally solitary predators, the success of a hunt depends on the ability of a single individual to restrain its prey. Retractile claws, used in combination with a powerful canine bite, enable the predator to subdue prey without the help of a conspecific (Gonyea & Ashworth, 1975). In addition to the dorsoventral stresses generated during the bite, the mandible must also be able to withstand the labiolingual and torsional stresses generated by struggling prey or when the canines encounter bone (Van Valkenburgh & Ruff, 1987). Indeed, when biting an unsecured, struggling prey, the direction of loading at the canine can vary unpredictably, putting the mandible at high risks of fracture (Alexander, 1981). To decrease the probability of accidental failure owing to unpredictable loads, the anterior region of the mandible must, thus, be strong labiolingually.

In canids, small dorsoventral force (Zx/L) at the canine indicates a relatively weak canine bite. Indeed, canids are known to hunt in packs and subdue their prey by delivering rapid, shallow bites (Ewer, 1973). Since prey capture does not depend on the action of a single individual, for which subduing prey rapidly and efficiently is essential, but on the collaboration of several individuals, canids do not need to deliver powerful canine bites. Instead, canids weaken their prey by inflicting numerous superficial wounds (Ewer, 1973; Biknevicius & Ruff, 1992a).

The dorsoventral mandibular force profiles (Zx/L) of hyaenids seem to be intermediate between the felid and canid conditions. The relatively lower Zx/L values at the canine than at the carnassial reflect, as in canids, pack hunting behaviour where prey is subdued through rapid, shallow bites delivered by the several individuals rather than by a single animal. However, the mandibular force profiles also indicate that the mandible at the canine is relatively stronger than in canids. This feature presumably reflects the buttressing of the symphyseal region against large dorsoventral stresses, as hyaenids are known to occasionally crack bones with their anterior dentition (Rensberger, 1995; Van Valkenburgh, 1996).

www.researchgate.net/publication/231858147_Mandibular_force_profiles_of_extant_Carnivorans_and_implications_for_the_feeding_behaviours_of_extinct_predators

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Systematics, phylogeny and feeding behavior of the oldest killer whale: a reappraisal of Orcinus citoniensis (Capellini, 1883) from the Pliocene of Tuscany (Italy)

Reaching body lengths of 9 m, killer whales (Orcinus orca) are the top mammalian predators of the present day oceans. These distinctive, cosmopolitan dolphins feature an extremely broad and diverse trophic spectrum, ranging from mollusks like octopuses and squids to other toothed whales and even baleen whales. Due to the lack of fossils that can be confidently assigned to Orcinus or close relatives thereof, the evolutionary origin of extant killer whales has rarely been addressed. Here, we provide an updated and thorough reappraisal of the systematics, phylogeny and feeding behavior of Orcinus citoniensis from the Pliocene of Tuscany (Italy), the only fossil species of killer whale currently known on the basis of diagnostic material. Our systematic and phylogenetic reassessment confirms that O. citoniensis is a bona fide species of Orcinus that mostly differs from the extant O. orca by virtue of a smaller body size (ca. 3.5 m). Besides Orcinus spp., the subfamily Orcininae is here recognized as a relatively early branching clade of delphinids that also includes the Italian Pliocene species “Tursiops” osennae, Hemisyntrachelus pisanus and Hemisyntrachelus cortesii. Our morphofunctional analysis supports a mainly piscivorous diet for O. citoniensis. In particular, the degree of apical tooth wear observed on the holotype is consistent with that shown by the extant generalist type of Atlantic killer whales while clearly differing from members of the cetacean-eating specialized types. The prominence of fish in the diet of O. citoniensis is further supported by the fine and shallow microwear features on the dentine exposed at the apical portion of the tooth crown. The emergence of Orcinus as one of the highest trophic level predators of the global oceans, especially at mid and high latitudes, may have involved some process of exaptation, well into the Pleistocene, when large eurytrophic sharks that used to be common and widespread in Pliocene times either became extinct or underwent a severe reduction of their biogeographic ranges.

www.researchgate.net/publication/363568094_Systematics_phylogeny_and_feeding_behavior_of_the_oldest_killer_whale_a_reappraisal_of_Orcinus_citoniensis_Capellini_1883_from_the_Pliocene_of_Tuscany_Italy

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A note and some crude calculations on how much damage a bite from a zebra can do (source->).





And a case report about a zebra bite on a human arm.

www.sciencedirect.com/science/article/pii/S2352644017300092

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Here is an interesting comparison between the jaw bones of different oceanic macropredators, Dunkleosteus, the great white shark, and killer whale.

The jaws of Carcharodon and Dunkleosteus performed very similarly in the amount of stress absorbed.

It is notable that, while there is a large difference in lower jaw robustness between Cetorhinus and Titanichthys (median von Mises stress of 0.78 MPa compared with 1.83 MPa, respectively), Carcharodon and Dunkleosteus performed very similarly. The median von Mises stress for Carcharodon was 85% of the respective value for Dunkleosteus. Dunkleosteus probably occupied the equivalent niche as Carcharodon, but their methods of subduing prey probably differed as a result of very efficient locomotion in the great white shark [68], which is unlikely to have been replicated in the heavy, less streamlined Dunkleosteus [69]. Similarly, some predatory strategies of Carcharodon, like the lateral head shake [70], may not have been plausible for Dunkleosteus. Consequently, the great white shark lower jaw was expected to prove more resistant to stress than the inferognathal of Dunkleosteus—and this may have been seen to a greater extent if cartilaginous properties were applied to the shark. Treating a great white shark jaw as homogeneous bone has previously resulted in underestimated stress resistance [48], and a lower Young’s modulus associated with calcified cartilage would result in higher jaw strain. On the other hand, prior research indicating that the bite force : body mass ratio of Dunkleosteus is roughly equivalent to that of the great white shark [29] suggests that similar stress resistances, when scaled to length, are to be expected.

On the other hand, Orcinus has jaws that experience considerably more stress than those of Carcharodon and Dunkleosteus.

The mandible of Orcinus is considerably more resistant to stress than that of Balaenoptera, but the median values are still notably higher than in Carcharodon and Dunkleosteus, the proposed analogues of the killer whale. Ecological reasons for this are difficult to determine, with the typical diet of an orca resembling the diet of a great white shark: centring on marine mammals [76] but sufficiently generalist to predate a wide range of species [77]. This ecological similarity would seem to suggest roughly equivalent jaw robustness, a pattern, which is not seen here.

royalsocietypublishing.org/doi/pdf/10.1098/rsos.200272

The orca specimen used for this study was NMML-1850, a transient (read: mammal-eating) orca.

sketchfab.com/3d-models/orca-pectoral-fin-nmml-1850-a1ecfd8a27194a66a8631545e5898343

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Dietary niche partitioning in Early Jurassic ichthyosaurs from Strawberry Bank

Jurassic ichthyosaurs dominated upper trophic levels of marine ecosystems. Many species coexisted alongside each another, and it is uncertain whether they competed for the same array of food or divided dietary resources, each specializing in different kinds of prey. Here, we test whether feeding differences existed between species, applying finite element analysis to ichthyosaurs for the first time. We examine two juvenile ichthyosaur specimens, referred to Hauffiopteryx typicus and Stenopterygius triscissus, from the Strawberry Bank Lagerstätte, a shallow marine environment from the Early Jurassic of southern England (Toarcian, ~183 Ma). Snout and cranial robusticity differ between the species, with S. triscissus having a more robust snout and cranium and specializing in slow biting of hard prey, and H. typicus with its slender snout specializing in fast, but weaker bites on fast-moving, but soft prey. The two species did not differ in muscle forces, but stress distributions varied in the nasal area, reflecting differences when biting at different points along the tooth row: the more robustly snouted Stenopterygius resisted increases or shifts in stress distribution when the bite point was shifted from the posterior to the mid-point of the tooth row, but the slender-snouted Hauffiopteryx showed shifts and increases in stress distributions between these two bite points. The differences in cranial morphology, dentition and inferred stresses between the two species suggest adaptations for dietary niche partitioning.

onlinelibrary.wiley.com/doi/10.1111/joa.13744