Figure - uploaded by Stephen W Wroe
Content may be subject to copyright.
Bite force adjusted for body mass allometry (BFQ), maximal prey size and feeding category in 31 extant mammalian carnivores. (RMPS, maximal prey size (1, greater than maximal body mass of predator; 2, less than maximal body mass of predator); FC, feeding category (1, hypercarnivore; 2, other); '-', insufficient data. Maximal body mass data largely from Meers (2002). For additional data see Electronic Appendix, section A.)
Source publication
We provide the first predictions of bite force (BS) in a wide sample of living and fossil mammalian predators. To compare between taxa, we calculated an estimated bite force quotient (BFQ) as the residual of BS regressed on body mass. Estimated BS adjusted for body mass was higher for marsupials than placentals and the Tasmanian devil (Sarcophilus...
Contexts in source publication
Context 1
... although the ability to bring down large prey in canids is related to cooperative hunting, it is still reflected in a higher BFQ. Within living Felidae, BFQ values were 57 and 75 for the two species that specialize in relatively small prey, while BFQ was 94 or greater for the seven known to take relatively large prey (table 2). B S adjusted for body mass was also low in bears (44-78), which are restricted to relatively small prey (Meers 2002). ...Context 2
... BFQ was 100 or higher in 15 of the 16 extant placental and marsupial carnivores sampled that take prey larger than their own maximal body masses. In 12 of the 14 extant species where maximal prey size was less than the species' mean body mass, BFQ was less than 100 (table 2). The difference between large and small prey specialists was significant (t(28)ZK4.92, ...Context 3
... considered in isolation, B S adjusted for body mass is not an infallible predictor. In the aardwolf (Proteles cristatus), BFQ is low (77), but higher than in some bears, a viverrid and two small cat species (table 2). Although this finding is consistent in that all take relatively small prey, it does not reflect the fact that P. cristatus subsists largely on termites. ...Similar publications
In addition to biting, it has been speculated that the forces resulting from pulling on food items may also contribute to feeding success in carnivorous vertebrates. We present an in vivo analysis of both bite and pulling forces in Varanus komodoensis, the Komodo dragon, to determine how they contribute to feeding behavior. Observations of cranial...
Studies on the effect of temperature on whole-animal performance traits other than locomotion are rare. Here we investigate the effects of temperature on the performance of the turtle feeding apparatus in a defensive context. We measured bite force and the kinematics of snapping in the Common Snapping Turtle (Chelydra serpentina) over a wide range...
Five striking and prey capture events of two goblin sharks were videotaped at sea for the first time, showing their extraordinary biting process. The goblin sharks swung their lower jaw downward and backward to attain a huge gape and then rapidly protruded the jaws forward a considerable distance. The jaws were projected at a maximum velocity of 3....
Citations
... To estimate the forces (Newtons) pulling each muscle insertion, the insertion area (mm 2 ) was multiplied by 0.3N/mm² based on the maximum tension produced by mammalian muscle fibres [30]. All biting simulations were unilateral (left and right side were simulated in different scenarios) so to compensate the balancing side muscle forces were multiplied by 0.6 of working side muscles, following [31]. ...
Cat-like carnivorans are a textbook example of convergent evolution with distinct morphological differences between taxa with short or elongated upper canines, the latest being often interpreted as an adaptation to bite at large angles and subdue large prey. This interpretation of the sabretooth condition is reinforced by a reduced taxonomic sampling in some studies, often focusing on highly derived taxa or using simplified morphological models. Moreover, most biomechanical analyses focus on biting scenarios at small gapes, ideal for modern carnivora but ill-suited to test for subduction of large prey by sabre-toothed taxa. In this contribution we present the largest 3D collection-based muscle-induced biting simulations on cat like carnivorans by running a total of 1,074 analyses on 17 different taxa at three different biting angles (30°, 60° and 90°) including both morphologies. While our results show a clear adaptation of extreme sabre-toothed taxa to bite at larger angles in terms of stress distribution, other performance variables display surprising similarities between all forms at the different angles tested, highlighting a continuous rather than bipolar spectrum of hunting methods in cat-like carnivorans and demonstrating a wide functional disparity and nuances of the sabretooth condition that cannot simply be characterized by specialized feeding biomechanics.
... One of the most used ways to calculate bite force is the dry-skull method developed by Thomason (1991), which reconstructs the adductor musculature to estimate the muscle forces solely using the skull morphology, modelling the jaws as simple levers. It has been applied in analyses of muscular and bite force in many organisms, including canids TA B L E 2 Total force inferred for the bites in the intrinsic scenarios (Christiansen & Wroe, 2007;Ellis et al., 2008;Nanova et al., 2017;Penrose et al., 2020;Wroe et al., 2005). ...
Cerdocyonina is a clade composed by the South‐American canids in which the bush dog (Speothos venaticus) is one of the most elusive species. Known for its unique morphology within the group, this small, bear‐like faced canid is the only member of the clade adapted to hypercarnivory, an almost exclusively meat‐based diet currently present only in usually large, pack‐hunting canids such as the grey wolf (Canis lupus). However, much of the biology of the bush dog is poorly understood, and inferences about its ecology, hunting strategies and diet are usually based on observation of captive individuals and anecdotal records, with reduced quantitative data to offer support. Here, we investigated the craniomandibular functional morphology of the bush dog through finite element analysis (FEA). FEA was employed to model the biting behaviour and to create extrinsic and intrinsic functional scenarios with different loads, corresponding to different bites used to subdue and process the prey. For comparison, the same modelling was applied to the skull of a grey wolf and a grey fox (Urocyon cinereoargenteus). Our analysis showed that the bush dog's responses to loading are more similar to the wolf's than to the fox's in most scenarios, suggesting a convergent craniomandibular functional morphology between these two hypercarnivorous species, despite their distinct phylogenetic positions and body sizes. Differences between the three taxa are noteworthy and suggested to be related to the size of the usual prey. The modelled bite force for the bush dog is relatively strong, about half of that estimated for the wolf and about 40% stronger than the fox's bite. The results strengthen with quantitative data the inferences of the bush dog as a pack‐hunting predator with prey size similar to its own, such as large rodents and armadillos, being specialised in subduing and killing its prey using multiple bites. Its similarity to the wolf also confirms anecdotal accounts of predation on mammals that are much larger than itself, such as peccaries and tapirs. These data highlight the ecological specialisation of this small canid in a continent where large, pack‐hunting canids are absent. Von Mises stress contour plots from finite element analysis of the intrinsic scenarios modelled to the mandibles of the bush dog (Speothos venaticus), grey wolf (Canis lupus) and grey fox (Urocyon cinereoargenteus). Asterisks indicate the placement of the tooth bite. The mean von Mises stress of each scenario is shown in the bottom right. CanU: unilateral canine‐driven bite; CarU: unilateral carnassial‐driven bite; CanB: bilateral canine‐driven bite; CarB: bilateral carnassial‐driven bite.
... These taxa also have the least optimized out-lever in the lower jaw. The anterior jaw is where maximal loads are dealt with (Wroe et al., 2005) and is therefore important when processing prey items. Plagiophthalmosuchus, most teleosaurids, and smaller individuals of Macrospondylus and ...
Throughout the Jurassic, a plethora of marine reptiles dominated ocean waters, including ichthyosaurs, plesiosaurs and thalattosuchian crocodylomorphs. These Jurassic ecosystems were characterized by high niche partitioning and spatial variation in dietary ecology. However, while the ecological diversity of many marine reptile lineages is well known, the overall ecological diversification of Teleosauroidea (one of the two major groups within thalattosuchian crocodylomorphs) has never been explored. Teleosauroids were previously deemed to have a morphologically conservative body plan; however, they were in actuality morphofunctionally more diverse than previously thought. Here we investigate the ecology and feeding specializations of teleosauroids, using morphological and functional cranio‐dental characteristics. We assembled the most comprehensive dataset to date of teleosauroid taxa (approximately 20 species) and ran a series of principal component analyses (PC) to categorize them into various feeding ecomorphotypes based on 17 dental characteristics (38 specimens) and 16 functionally significant mandibular characters (18 specimens). The results were examined in conjunction with a comprehensive thalattosuchian phylogeny (153 taxa and 502 characters) to evaluate macroevolutionary patterns and significant ecological shifts. Machimosaurids display a well‐developed ecological shift from: (1) slender, pointed tooth apices and an elongate gracile mandible; to (2) more robust, pointed teeth with a slightly deeper mandible; and finally, (3) rounded teeth and a deep‐set, shortened mandible with enlarged musculature. Overall, there is limited mandibular functional variability in teleosaurids and machimosaurids, despite differing cranial morphologies and habitat preferences in certain taxa. This suggests a narrow feeding ecological divide between teleosaurids and machimosaurids. Resource partitioning was primarily related to snout and skull length as well as habitat; only twice did teleosauroids manage to make a major evolutionary leap to feed distinctly differently, with only the derived machimosaurines successfully radiating into new feeding ecologies. An investigation into teleosauroid functional morphology and ecological diversification. Using dental and mandibular characteristics, results suggest that teleosauroids displayed limited mandibular functional variability, aside from certain subgroups which exploited larger/harder prey items.
... Devils are scavengers that regularly consume hard bone and employ a range of prey-processing techniques that expose their teeth to unpredictable loads [40,[58][59][60]. In addition to having the highest predicted bite force of any extant mammal when scaled for body size [61], Van Valkenburgh & Ruff [4] also proposed that the relatively circular cross-sections of hyaenas were an adaptation to scavenging, and our observations of devil canines support this. ...
Canine teeth are vital to carnivore feeding ecology, facilitating behaviours related to prey capture and consumption. Forms vary with specific feeding ecologies; however, the biomechanics that drive these relationships have not been comprehensively investigated. Using a combination of beam theory analysis (BTA) and finite-element analysis (FEA) we assessed how aspects of canine shape impact tooth stress, relating this to feeding ecology. The degree of tooth lateral compression influenced tolerance of multidirectional loads, whereby canines with more circular cross-sections experienced similar maximum stresses under pulling and shaking loads, while more ellipsoid canines experienced higher stresses under shaking loads. Robusticity impacted a tooth's ability to tolerate stress and appears to be related to prey materials. Robust canines experience lower stresses and are found in carnivores regularly encountering hard foods. Slender canines experience higher stresses and are associated with carnivores biting into muscle and flesh. Curvature did not correlate with tooth stress; however, it did impact bending during biting. Our simulations help identify scenarios where canine forms are likely to break and pinpoint areas where this breakage may occur. These patterns demonstrate how canine shape relates to tolerating the stresses experienced when killing and feeding, revealing some of the form–function relationships that underpin mammalian carnivore ecologies.
... Hogue (2008) found that marsupial folivores show an increase in the vertical bending strength of the mandibular corpus, as described for primates (e.g., Anapol and Lee 1994;Daegling 1992;Anton 1996). The mandibular morphology of carnivorous marsupials shows characters aimed at an improvement in the mechanical advantages in the bite system, convergent with that of carnivorans among placentals (e.g., Wroe et al. 2005;Wroe and Milne 2007;Prevosti et al. 2012; see above). However, despite the strong morphological differences in the great diversity of living marsupials, jaw growth patterns are conservative (Table 2). ...
... However, constraints involved in the differences between carnivorous marsupials and eutherians also influence biting abilities, as marsupials have larger and more robust zygomatic arches, reflecting more powerful masseters. Marsupials also have smaller braincases that allow for more room for jaw adductor muscles, thus resulting in higher bite forces (Wroe et al. 2005), although the temporomandibular joint in marsupials is in a less advantageous position. This pattern, however, was obtained from a wide range of marsupial and eutherian taxa (Wroe et al. 2005), and how much of this occurs within Didelphidae is still unclear. ...
... Marsupials also have smaller braincases that allow for more room for jaw adductor muscles, thus resulting in higher bite forces (Wroe et al. 2005), although the temporomandibular joint in marsupials is in a less advantageous position. This pattern, however, was obtained from a wide range of marsupial and eutherian taxa (Wroe et al. 2005), and how much of this occurs within Didelphidae is still unclear. ...
Didelphids are considered morphologically conservative and unspecialized; however, information about different morphological systems is not equally available among its members. Recent research is unveiling variation in their morphology that can be related to function, in the skeleton or soft tissues. Yet, differences in didelphid tribosphenic molars correlate poorly with their diet (possibly due to highly overlapping diets across taxa), and variation in cranial and mandibular shape can be partially related to function, although allometry and phylogeny play major roles in constraining that variation. Morphological variation in postcranial elements relates mostly to sexual dimorphism and locomotor habits, particularly in larger opossums, and osteological characters have been used for inferences about the locomotion habit of extinct taxa. Didelphid myology is generally similar within the group, but with some variation associated with adaptations to different locomotion habits (e.g., arboreal, scansorial, cursorial, and semiaquatic). Gross digestive morphology also varies partially with diet in a few studied species, but digestive histology data are still too incipient for adequate form function estimates. While the knowledge on reproductive anatomy is highly unbalanced, information on reproductive behavior is too scarce and anecdotal for reliable inferences on the function of known reproductive morphology. Overall, while the few better-studied taxa are revealing interesting patterns of relationships between morphology, function, and history in Didelphidae, the family still needs more detailed analyses, given its ecological and taxonomic diversity.
... Holding pennation angles and the relationship between fibre length and muscle length constant enables us to investigate the effects of three-dimensional muscle volumes and curved versus straight muscle length calculations; different pennation angles and muscle fibre lengths would change the absolute PCSAs and forces, but not the calculated relative difference in PCSAs and muscle forces between the two methods tested. Muscle force was calculated by multiplying PCSA by an isometric muscle stress value of 0.3 N mm −2 following Thomason [17] and Wroe et al. [38]. ...
... PSCA was calculated by dividing muscle volume by the length, assuming that muscle length equals fibre length and assuming a parallelfibred muscle for simplicity. Muscle force was calculated by multiplying PCSA by an isometric muscle stress value of 0.3 N mm −2 , following Thomason [17] and Wroe et al. [38]. PSCAs are given in mm 2 royalsocietypublishing.org/journal/rsos R. Soc. ...
Accurate muscle reconstructions can offer new information on the anatomy of fossil organisms and are also important for biomechanical analysis (multibody dynamics and finite-element analysis (FEA)). For the sake of simplicity, muscles are often modelled as point-to-point strands or frustra (cut-off cones) in biomechanical models. However, there are cases in which it is useful to model the muscle morphology in three dimensions, to better examine the effects of muscle shape and size. This is especially important for fossil analyses, where muscle force is estimated from the reconstructed muscle morphology (rather than based on data collected in vivo). The two main aims of this paper are as follows. First, we created a new interactive tool in the free open access software Blender to enable interactive three-dimensional modelling of muscles. This approach can be applied to both palaeontological and human biomechanics research to generate muscle force magnitudes and lines of action for FEA. Second, we provide a guide on how to use existing Blender tools to reconstruct distorted or incomplete specimens. This guide is aimed at palaeontologists but can also be used by anatomists working with damaged specimens or to test functional implication of hypothetical morphologies.
... The lengths of lever arms in mandible have been shown to differ among carnivoran taxa, with the mustelids and felids having a shorter outlever at the carnassial and canine relative to the inlever than the canids and ursids (Radinsky, 1981a(Radinsky, , 1981bVan Valkenburgh & Ruff, 1987). Previous studies have reported bite forces estimated using the outlever length to the carnassial and canine and the inlever length in crania and mandibles of carnivoran species (Christiansen & Adolfssen, 2005;Christiansen & Wroe, 2007;Wroe et al., 2005). The estimated bite forces at the carnassial and canine relative to body size are highest in specialized herbivores and carnivores feeding on large prey and lowest in insectivores among carnivorans (Christiansen & Wroe, 2007). ...
... A relatively shorter outlever could generate a stronger bite force that would be advantageous for killing larger prey, whereas a relatively longer outlever allows for faster canine biting, which would benefit predators who capture small, agile prey ). It has been estimated that, among canids, the bite force at the canines relative to body size was highest in species hunting large prey (Christiansen & Wroe, 2007;Damasceno et al., 2013;Wroe et al., 2005). Canids that feed on large prey have been shown to have relatively shorter jaws than canids that feed on small prey or other foods . ...
Species in the mammalian order Carnivora have extremely diverse diets. The association between diet and craniodental morphology in carnivorans has been the subject of a number of studies. The distance from the jaw joint to the tooth positions may contribute to the ability to acquire and process food because it corresponds to the outlever arm when the jaw functions as a lever to generate a bite force. A shorter outlever arm relative to the inlever arm of the masticatory muscle generates a higher bite force. This study measured the distances from the jaw joint to different points of the teeth as the outlever lengths in the crania of terrestrial Carnivora species to show that outlever lengths corrected for phylogeny and a measure of the inlever length differ according to dietary habits among carnivorans. The distance from the jaw joint to the last molar was shortest in folivores, followed by aquatic prey specialists, suggesting that consumption of tough plant materials and, to some extent, aquatic prey with hard exoskeletons has favoured the evolution of a shorter outlever to allow stronger bites with enlarged molars. In contrast, among Canidae species, a shorter outlever to canines was associated with feeding on large prey, but this association was not found across carnivorans, suggesting that the correlated evolution of a shorter outlever at the canines and specialization for feeding on large prey depends on foraging and hunting behaviours. Combined, these findings provide some evidence that distances from the jaw joint to different points of the teeth are adapted to different feeding ecologies in carnivorans. In craniodental morphology, the distance from the jaw joint to the teeth corresponds to the outlever arm when the jaw functions as a lever to generate a bite force, with a shorter outlever converting more muscle force into bite force. We performed phylogenetic comparative analyses to show that the outlever lengths at different points of the teeth in the cranium differ according to dietary habits in the mammalian order Carnivora. This study provides evidence for adaptations of the distance from the jaw joint to the teeth to different feeding ecologies in Carnivora.
... Both traits may be important in physically attacking rivals (e.g., wrestling, biting) ( Fig. 1B and Movie S1). For example, head width is correlated with bite force across mammalian taxa (41), and bite force predicts contest success in some systems (42,43). In contrast to the number of males, the positive impact of oldest male age was not likely related to physical properties; oldest males did not also have the heaviest weights (proportion of oldest males that were also the heaviest males in their groups = 13/66 males, 19.7%) or widest heads (proportion of oldest males that were also males with widest heads in their groups = 27/67 males, 40.3%) of males in their groups. ...
Conflicts between social groups or “intergroup contests” are proposed to play a major role in the evolution of cooperation and social organization in humans and some nonhuman animal societies. In humans, success in warfare and other collective conflicts depends on both fighting group size and the presence and actions of key individuals, such as leaders or talismanic warriors. Understanding the determinants of intergroup contest success in other warlike animals may help to reveal the role of these contests in social evolution. Using 19 y of data on intergroup encounters in a particularly violent social mammal, the banded mongoose ( Mungos mungo ), we show that two factors, the number of adult males and the age of the oldest male (the “senior” male), have the strongest impacts on the probability of group victory. The advantage conferred by senior males appears to stem from their fighting experience. However, the galvanizing effect of senior males declines as they grow old until, at very advanced ages, senior males become a liability rather than an asset and can be evicted. As in human conflict, strength in numbers and the experience of key individuals combine to determine intergroup contest success in this animal society. We discuss how selection arising from intergroup contests may explain a suite of features of individual life history and social organization, including male eviction, sex-assortative alloparental care, and adult sex ratio.
... ultimately determine the 3D model data that serve as the foundation for achieving scientific discoveries in the fields of morphology, biomechanics, and medicine, it is important to examine how different segmentation procedures relate to variation in 3D models and associated quantitative data [5][6][7][8] . Huotilainen et al. 1 demonstrated that variations in the DICOM-to-STL conversion step of processing computed tomography (CT) data from the same individual significantly change the morphology of subsequent 3D anatomical models. ...
Finite element analysis is a powerful computational technique for augmenting biomedical research, prosthetics design, and preoperative surgical assessment. However, the validity of biomechanical data obtained from finite element analysis is dependent on the quality of the preceding data processing. Until now, little information was available about the effect of the segmentation process on finite element models and biomechanical data. The current investigation applied 4 segmentation approaches to 129 femur specimens, yielding a total of 516 finite element models. Biomechanical data including average displacement, pressure, stress, and strain were collected from experimental groups based on the different segmentation approaches. The results indicate that only a 5.0% variation in the segmentation process leads to statistically significant differences in all 4 biomechanical measurements. These results suggest that it is crucial for consistent segmentation procedures to be applied to all specimens within a study. This methodological advancement will help to ensure that finite element data will be more accurate and that research conclusions will have greater validity.
