Functional Morphology of Animal Feeding Apparata

[Supercommunist]

Cockatoo chopping through wood to get to food.

13:24



Just goes to show that a ceratopsians beak were also probably pretty gnarly weapons.

[Infinity Blade]

^For what it’s worth Thomas R. Holtz expects the large ceratopsids like Triceratops to have been able to bite harder than T. rex. It would be nice to have a study to confirm how hard Triceratops could bite once and for all, but we're probably talking really strong bites coupled with sharp, hooked beaks.

38:02

"...the expectation is the strongest bite in all Dinosauria is not Tyrannosaurus. The Triceratops and the other giant ceratopsids probably blew Tyrannosaurus out of the water with the actual amount of force they could generate with a bite."

[Exalt]

What would they have been using all of that force for?

I don't imagine they'd need it to deal with trees since they are already so large. Would it be caused by a pressure from intraspecific combat, that might also help to defend against predators?

[Infinity Blade]

Oct 6, 2023 4:05:34 GMT 5 Exalt said:

What would they have been using all of that force for?

I don't imagine they'd need it to deal with trees since they are already so large. Would it be caused by a pressure from intraspecific combat, that might also help to defend against predators?

If they did indeed bite that hard (or hell, even if not, because they had to have been biting "hard" to SOME extent), I think it would have been some adaptation for whatever vegetation they had to process, but also, yes, I suppose combat and defense. As far as I'm aware, ceratopsians always had skulls that could exert impressive bite forces, even during the ages that they were just small bipeds, so it's not hard to imagine ceratopsians as a whole biting in combat. We know for a fact that Protoceratops bit predators; it doesn't take a huge leap of faith to believe that ceratopsids retained this behavior from whatever hornless but frilled (basically, probably protoceratopsid-like) ancestors they evolved from.

[Supercommunist]

Wouldn't safety factor be an issue? From what Iunderstand beaks aren't asdurable as toothy jaws.

[Infinity Blade]

Maybe, and it is true that neither keratin nor bone are as hard as enamel. But it may also be that large ceratopsids "accepted" these lower safety factors if they really did bite this hard.

[Exalt]

Huh, I never would have imagined plants being THAT tough without them literally biting strong trees.

Wait, are you telling me that they started getting the characteristic ceratopsian features before becoming quadrupedal?

[Supercommunist]

Loosely related by skallagrim acquired a tiger shark tooth club. At 6:06 you can see how easily they slide into ballistic gel.

www.youtube.com/watch?v=dpCeXxfD-ZE&ab_channel=Skallagrim

[Infinity Blade]

Three-dimensional dental microwear in type-Maastrichtian mosasaur teeth (Reptilia, Squamata)

Mosasaurs (Squamata, Mosasauridae) were large aquatic reptiles from the Late Cretaceous that filled a range of ecological niches within marine ecosystems. The type-Maastrichtian strata (68–66 Ma) of the Netherlands and Belgium preserve remains of five species that seemed to have performed different ecological roles (carnivores, piscivores, durophages). However, many interpretations of mosasaur diet and niche partitioning are based on qualitative types of evidence that are difficult to test explicitly. Here, we apply three-dimensional dental microwear texture analysis (DMTA) to provide quantitative dietary constraints for type-Maastrichtian mosasaurs, and to assess levels of niche partitioning between taxa. DMTA indicates that these mosasaurs did not exhibit neatly defined diets or strict dietary partitioning. Instead, we identify three broad groups: (i) mosasaurs Carinodens belgicus and Plioplatecarpus marshi plotting in the space of modern reptiles that are predominantly piscivorous and/or consume harder invertebrate prey, (ii) Prognathodon saturator and Prognathodon sectorius overlapping with extant reptiles that consume larger amounts of softer invertebrate prey items, and (iii) Mosasaurus hoffmanni spanning a larger plot area in terms of dietary constraints. The clear divide between the aforementioned first two groups in texture-dietary space indicates that, despite our small sample sizes, this method shows the potential of DMTA to test hypotheses and provide quantitative constraints on mosasaur diets and ecological roles.

www.nature.com/articles/s41598-023-42369-7

[Infinity Blade]

Comparative Feeding Biomechanics of Lystrosaurus and the Generalized Dicynodont Oudenodon

Differences in cranial morphology among the Dicynodontia have been correlated with changes in masticatory function, and hence, dietary preference. Although the derived masticatory apparatus of dicynodonts allowed propaliny, it has previously been hypothesized that Lystrosaurus primarily utilized powerful orthal jaw movements to process fibrous vegetation. Cranial specializations of Lystrosaurus, such as shortened and deepened cranium and a mobile premaxilla-nasal suture, are thought to have increased the efficiency of its masticatory system compared with generalized Permian dicynodonts. Here we aim to test this assertion using biomechanical modeling techniques. We use finite element analysis (FEA) and a study of cranial functional morphology to compare the biomechanical performance of the crania of Lystrosaurus and Oudenodon, a generalized dicynodont, during orthal bite simulations. Muscle forces were estimated for each dicynodont using the dry skull method and applied to each cranium to produce a reaction force at a bite point. Patterns and average magnitude of Von Mises stress in each dicynodont cranium and in segmented regions of interest were assessed. During orthal bite simulations, higher stress occurs throughout the Oudenodon cranium, indicating that the cranium of Lystrosaurus is more resistant to normal, static feeding loads. Despite this difference in stress magnitude, patterns of stress are similar within both taxa. The FE-stress results, along with mechanical advantage of adductor musculature, a broad symphyseal contact, and other cranial features suggest that Lystrosaurus may have used a snapping bite to cope with tough fibrous vegetation.

anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.20906

[Infinity Blade]

Evolution of Hystricomorphy in the Nimravidae (Carnivora; Barbourofelinae): Evidence for complex character convergence with rodents

Barbourofelis fricki is a saber‐tooth with canines approximately 22 cm long and the largest mandibular flange among nimravids. The jaw‐rotation for canine clearance and biting exceeded 115°. This gape was coupled with extensive cranial musculoskeletal reorganization, including extension of the deep masseter through a greatly enlarged infraorbital foramen onto the muzzle (hystricomorphy). This condition was previously described in rodents, wherein the anteriorly originating deep masseter improved the mechanical advantage of anterior mandibular movements involved in gnawing. The anterior origin of the deep masseter in barbourofelins facilitated jaw closure from gapes over 90° in four ways: 1) a lengthened muscle excursion permitted greater contraction distance; 2) the line of action at all gapes improved, particularly for those over 90°; 3) anteroposterior masseter origin length increased; and 4) sequential muscle segment activation provided smooth muscular contraction and the ability to control mandibular position precisely. An occipital inclination of 90° or more and an elongated axis spinous process in barbourofelins and some rodents also permitted increased snout elevation.

www.tandfonline.com/doi/abs/10.1080/10292380009380565

[Infinity Blade]

A characteristic feature of vultures is their consumption of carrion. Although all species of vultures are obligate scavengers, as they all feed on carrion, field observations have revealed a different intensity of scavenging and a preference for different parts of a carcass, which has most likely favoured their coexistence (Kruuk, 1967; König, 1974, 1983; Houston, 1988). Three primary groups based on dietary preferences have been described: gulpers, rippers and scrappers (Kruuk, 1967; König, 1974, 1983; Houston, 1988; Hertel, 1994). Gulpers feed on soft tissues; they remove pieces of soft meat by inserting their head and neck through skin openings and engulfing the pieces by raising their head. Rippers feed on more superficial, tough tissues such as skin, muscle and tendons; they tear off pieces of these tissues using their feet as an anchor. Scrappers have a chicken-like feeding behaviour that involves pecking small pieces of meat on and around carcasses.

These three groups are reflected in the morphology of vultures. Gulpers have slender skulls, long, bald necks and bald heads. These features are considered to be adaptive to their feeding mode (soft-food-swallowing). A slender skull and a long neck may facilitate access to soft tissues located deep inside the carcass, whereas a bald head or neck may decrease the probability of infection (Kruuk, 1967; König, 1974, 1983; Houston 1988; Hertel, 1994). Rippers display wider skulls and stronger beaks than gulpers and feathers are generally present on the neck. Hertel (1994) suggested that a wide skull could provide greater moment arms to the neck muscles involved in feeding, facilitating manoeuvrability for tearing off pieces of dry skin and hard fibrous tissue from a carcass (hard-tearing-swallowing). A strong beak would also be advantageous for this purpose. Finally, scrappers possess a slender skull and the weakest beak, unsuitable for hard-tearing and engulfing large pieces of meat, but suitable for pecking small pieces of tissue on and around a carcass (pecking-swallowing).

According to this study, rippers, gulpers and scrappers display the strongest, intermediate and weakest beaks, respectively, and the widest, narrowest and intermediate/narrow crania, respectively. These differences are believed to be adaptive. These respective cranium morphologies would provide the strength necessary for rippers to tear off firmly attached tissues, the ability for gulpers to reach the soft tissues deep inside a carcass, and the ability for scrappers to rapidly peck pieces of loose tissue from the ground and a carcass.

In the present study, we demonstrated that these three feeding groups also emerge when postcranial elements are included in the analysis. However, the resulting classification differs slightly from the categorisation based on skull morphology. In the present work, G. barbatus and G. angolensis, which previously were clustered with the gulpers by Hertel (1994), were predicted to be a ripper and a scrapper, respectively. In agreement with previous studies (Kruuk, 1967; König, 1974, 1983; Hertel, 1994), we have demonstrated that cranium shape is a diagnostic feature for distinguishing feeding groups. However, in the present study, the cranium shape of G. barbatus was closer to that of rippers rather than gulpers (Figs. 5A and S2). The large skull (cranium and mandible) of G. barbatus is a striking feature when one observes its skeleton for the first time (compare the bone proportions in Fig. 6, Fig. 7). Moreover, we discovered that a diagnostic feature not previously considered is the mandible shape (ML/MW), which classifies G. barbatus more closely to rippers than gulpers (Fig. 5B).

www.sciencedirect.com/science/article/pii/S0944200621000544

[Infinity Blade]

Predatory synapsid ecomorphology signals growing dynamism of late Palaeozoic terrestrial ecosystems

Terrestrial ecosystems evolved substantially through the Palaeozoic, especially the Permian, gaining much new complexity, especially among predators. Key among these predators were non-mammalian synapsids. Predator ecomorphology reflect interactions with prey and competitors, which are key controls on carnivore diversity and ecology. Therefore, carnivorous synapsids may offer insight on wider ecological evolution as the first complex, tetrapod-dominated, terrestrial ecosystems formed through the late Palaeozoic. Using morphometric and phylogenetic comparative methods, we chart carnivorous synapsid trophic morphology from the latest Carboniferous to the earliest Triassic (307-251.2 Ma). We find a major morphofunctional shift in synapsid carnivory between the early and middle Permian, via the addition of new feeding modes increasingly specialised for greater biting power or speed that captures the growing antagonism and dynamism of terrestrial tetrapod predator-prey interactions. The further evolution of new hypo- and hypercarnivorous synapsids highlight the nascent intrinsic pressures and complexification of terrestrial ecosystems across the mid-late Permian.

www.nature.com/articles/s42003-024-05879-2

[Supercommunist]

In regards to the theropod vs komodo teeth comparison one paper pointed out that komodos don't have many front teeth to enable to them to tongue flick.

The researchers also noticed that the front teeth of the Komodo adults are either very small or completely missing. This unusual dental morphology correlates well with their tongue-flicking behavior, using the slender, forked snake-like tongue to forage for prey without having to open the mouth.

So on top of having larger skulls and more evenly spaced serrations, predatory theropods had another biting advantage over komodos.
phys.org/news/2024-02-adult-komodo-teeth-similar-theropod.html

[Infinity Blade]

Bending performance changes during prolonged canine eruption in saber-toothed carnivores: A case study of Smilodon fatalis

The canine of saber-toothed predators represents one of the most specialized dental structures known. Hypotheses about the function of hypertrophied canines range from display and conspecific interaction, soft food processing, to active prey acquisition. Recent research on the ontogenetic timing of skull traits indicates the adult canine can take years to fully erupt, but the consequences of prolonged eruption on inferences of canine functional morphology are missing from current discourse and have not been quantified. Here I evaluate hypotheses about adult canine bending strength and stiffness, respectively, during eruption in the felid Smilodon fatalis. Simulated eruption sequences of three adult canines were generated from specimen models to assess shifting cross-sectional geometry properties, and bending strength and stiffness under laterally directed loads were estimated using finite element analysis. Consistent with beam theory expectations, S. fatalis canine cross-sectional geometry is optimized for increased bending strength with increased erupted height. However, canine cross-sectional geometry changes through eruption exaggerate rather than minimize lateral deflection. Spatial constraint for maximum root length from adjacent sensory structures in the maxilla and the recently identified universal power law are hypothesized to limit the growth capacity of canine anteroposterior length and, consequently, maintenance of bending stiffness through eruption. Instead, the joint presence of the deciduous and adult canines for >50% of the adult canine eruption period effectively increases canine mediolateral width and brings bending strength and stiffness estimates closer to theoretical optima. Similarly prolonged retention of deciduous canines in other sabertooths suggests dual-canine buttressing is a convergently evolved strategy to maximize bending strength and stiffness.

anatomypubs.onlinelibrary.wiley.com/doi/10.1002/ar.25447