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Historically, predicting ursid feeding behaviour on the basis of morphometric and mechanical analyses has proven difficult. Here, we apply three‐dimensional finite element analysis to models representing five extant and one fossil species of bear. The ability to generate high bite forces, and for the skull to sustain them, is present in both the gi...
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... finite element models were assembled from computed tomography (CT) data representing five extant species (brown bear, Asian bear, black bear, polar bear and giant panda) and one fossil ursid A. africanum (SI Table S1). For extant taxa, preprocessing followed the previously published protocols Moreno et al., 2008;Wroe, 2008;Degrange et al., 2010;Wroe et al., 2010). ...
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... forces and bite force quotients [i.e. bite forces adjusted for body mass (Wroe et al., 2005)] were derived from the unscaled FEMs (see Table 1). Body masses were estimated for each specimen using an equation presented for ursids based on skull length (Van Valkenburgh, 1990). ...
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... absolute terms, bite force at the canines is greatest in A. af- ricanum (4566 N) and least in the Asian bear (1217 N). Bite force adjusted for body mass (bite force quotient, BFQ) was much higher in A. africanum and the giant panda than in any other species/specimens (Table 1). Lowest values for BFQ were for the Asian bear and the polar bear. ...
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... 4566 N, our 3D bilateral canine bite force estimate for A. africanum is the highest predicted for any mammal, being considerably greater than the equivalent for a very large male African lion (Panthera leo) (Wroe, 2008). A. africanum also had a very powerful bite for its size as indicated by a high BFQ value (Table 1). ...
Citations
... In the past 15 years, the FE method has become a ubiquitous tool in the repertoire of evolutionary biologists (Kolston, 2000;Rayfield, 2007), although it has rarely been used to model the fish (or any other vertebrates') hearing system. FE analysis is notably often used in paleontology to predict the abilities of extinct taxa to withstand loads induced by a biomechanical function, like chewing, for example, or walking (e.g., Macho et al., 2005;Oldfield et al., 2012). As the extinct specimen in focus cannot be tested in vivo, digital versions of the morphology, materials, and loads can be modelled and analysed. ...
Fishes, including elasmobranchs (sharks, rays, and skates), present an astonishing diversity in inner ear morphologies; however, the functional significance of these variations and how they confer auditory capacity is yet to be resolved. The relationship between inner ear structure and hearing performance is unclear, partly because most of the morphological and biomechanical mechanisms that underlie the hearing functions are complex and poorly known. Here, we present advanced opportunities to document discontinuities in the macroevolutionary trends of a complex biological form, like the inner ear, and test hypotheses regarding what factors may be driving morphological diversity. Three-dimensional (3D) bioimaging, geometric morphometrics, and finite element analysis are methods that can be combined to interrogate the structure-to-function links in elasmobranch fish inner ears. In addition, open-source 3D morphology datasets, advances in phylogenetic comparative methods, and methods for the analysis of highly multidimensional shape data have leveraged these opportunities. Questions that can be explored with this toolkit are identified, the different methods are justified, and remaining challenges are highlighted as avenues for future work.
... Rarely documented are its postcranial skeletons, and a complete humerus has never been reported. For an ursid reaching to a body size of 400 kg and with controversial diet (Sorkin 2006a;Oldfield et al., 2012), its limb bones contain much-needed information about its locomotion as well as predatory behaviors. ...
... The reduction of these structures is a factor that limited the effectiveness of Agriotherium for hunting and retention of large prey. These factors influenced the diet of Agriotherium that was not strictly carnivorous (Sorkin, 2006a;Hendey, 1980;Oldfield et al., 2012). ...
A complete humerus referred to Agriotherium is described, collected from early-late Hemphillian deposits from Zacatecas. Agriotherium is widely represented by isolated molars, mandibles, and maxillae in early-late Hemphillian faunas of Eurasia and North America. In the literature, postcranial elements are scarce and briefly described with little detail. The greatest diversity is known from the Langebaanweg quarry in South Africa; however, the only complete specimen is from Mexico. The proximal end is described, and the humerus shares similarities with the description of the distal end from South Africa, in which the medial epicondyle and crest of the lateral epicondyle are reduced, which can be considered as a limitation in the hunting of larger prey for food. This implies that Agriotherium was not strictly carnivorous but was a predator-scavenger with an omnivorous diet that included plants and fruits.
... As routinely employed in FE analyses (e.g. [23][24][25][26][27][28]), we reconstructed or retrodeformed some models of fossil taxa. To assure transparency, a complete description of the various reconstruction and retro-deformation steps undertaken is available in Figures S1-S9. ...
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.
... While initially common in engineering, architecture, and orthopaedic sciences, it is now widely used to assess the biomechanics of the human musculoskeletal system, and in recent years it has been a crucial tool in understanding vertebrate biomechanics and evolution (Ross, 2005;Rayfield, 2007). FEA has been used in studies of 2D (Rayfield, 2004;Rayfield, 2005a;Rayfield, 2005b;Pierce, Angielczyk & Rayfield, 2008;Pierce, Angielczyk & Rayfield, 2009;Fletcher, Janis & Rayfield, 2010;Ma et al., 2021) and 3D structures (Moreno et al., 2008;Bell, Snively & Shychoski, 2009;Oldfield et al., 2012;Cost et al., 2019;Rowe & Snively, 2021) to assess patterns and magnitudes of stresses and strain in both extant and extinct organisms, as well as suture morphology in the crania of reptiles (Rayfield, 2005a;Rayfield, 2005b;Jones et al., 2017) and mammals (Bright & Gröning, 2011;Bright, 2012). While studies involving FEA commonly focus on stress and strain occurring in the skull during feeding (Rayfield, 2007), studies may also examine the biomechanics of other vertebrate appendages (Arbour & Snively, 2009;Lautenschlager, 2014;Bishop et al., 2018). ...
Finite element analysis (FEA) is a commonly used application in biomechanical studies of both extant and fossil taxa to assess stress and strain in solid structures such as bone. FEA can be performed on 3D structures that are generated using various methods, including computed tomography (CT) scans and surface scans. While previous palaeobiological studies have used both CT scanned models and surface scanned models, little research has evaluated to what degree FE results may vary when CT scans and surface scans of the same object are compared. Surface scans do not preserve the internal geometries of 3D structures, which are typically preserved in CT scans. Here, we created 3D models from CT scans and surface scans of the same specimens (crania and mandibles of a Nile crocodile, a green sea turtle, and a monitor lizard) and performed FEA under identical loading parameters. It was found that once surface scanned models are solidified, they output stress and strain distributions and model deformations comparable to their CT scanned counterparts, though differing by notable stress and strain magnitudes in some cases, depending on morphology of the specimen and the degree of reconstruction applied. Despite similarities in overall mechanical behaviour, surface scanned models can differ in exterior shape compared to CT scanned models due to inaccuracies that can occur during scanning and reconstruction, resulting in local differences in stress distribution. Solid-fill surface scanned models generally output lower stresses compared to CT scanned models due to their compact interiors, which must be accounted for in studies that use both types of scans.
... This is a computational engineering tool that involves simulating behaviors or actions of interest on digital models rendered from scanned specimens (Richmond et al. 2005;Rayfield 2007;Panagiotopoulou 2009;Bright 2014). Relative performance metrics such as mechanical efficiency (output force/total applied muscle force), stress (force per unit area), and strain ( length/initial length) can be obtained from modeled skulls and are often attributed to known or predicted diets and feeding behaviors across the species examined (e.g., Wroe et al. 2007Wroe et al. , 2013Porro et al. 2011;Ross et al. 2011;Cox et al. 2012;Oldfield et al. 2012;Smith et al. 2015;Tseng and Flynn 2015;Godinho et al. 2018;Lautenschlager et al. 2018;Ledogar et al. 2018;Mitchell et al. 2018;Panagiotopoulou et al. 2020). In order to highlight potential biomechanical deficits introduced by soft diets in captive-reared fauna, we employ the finite element method here to test the influence that contrasting food material properties have on bone deposition, and resulting biting performance, in a single generation of animals raised from weaning. ...
The rescue and rehabilitation of young fauna is of substantial importance to conservation. However, it has been suggested that incongruous diets offered in captive environments may alter craniofacial morphology and hinder the success of reintroduced animals. Despite these claims, to what extent dietary variation throughout ontogeny impacts intrapopulation cranial biomechanics has not yet been tested. Here, finite element models were generated from the adult crania of 40 rats (n = 10 per group) that were reared on 4 different diet regimes and stress magnitudes compared during incisor bite simulations. The diets consisted of (1) exclusively hard pellets from weaning, (2) exclusively soft ground pellet meal from weaning, (3) a juvenile switch from pellets to meal, and (4) a juvenile switch from meal to pellets. We hypothesized that a diet of exclusively soft meal would result in the weakest adult skulls, represented by significantly greater stress magnitudes at the muzzle, palate, and zygomatic arch. Our hypothesis was supported at the muzzle and palate, indicating that a diet limited to soft food inhibits bone deposition throughout ontogeny. This finding presents a strong case for a more variable and challenging diet during development. However, rather than the "soft" diet group resulting in the weakest zygomatic arch as predicted, this region instead showed the highest stress among rats that switched as juveniles from hard pellets to soft meal. We attribute this to a potential reduction in number and activity of osteoblasts, as demonstrated in studies of sudden and prolonged disuse of bone. A shift to softer foods in captivity, during rehabilitation after injury in the wild for example, can therefore be detrimental to healthy development of the skull in some growing animals, potentially increasing the risk of injury and impacting the ability to access full ranges of wild foods upon release. We suggest captive diet plans consider not just nutritional requirements but also food mechanical properties when rearing wildlife to adulthood for reintroduction.
... Here, we use the 'dry-skull' method and the finite element analysis (FEA) to estimate the bite force of Z. varolai and test the bite performances of this extinct macroraptorial sperm whale. FEA has proven to be a powerful tool to investigate form and function of extinct vertebrates (Rayfield et al. 2001;Hassan et al. 2002;McHenry et al. 2007;Wroe et al. 2007;Bell et al. 2009;Oldfield et al. 2012;Foffa et al. 2014;Snively et al. 2015), but such a biomechanical approach has never been used before on a macroraptorial sperm whale. The results obtained from the FEA bite simulations provide informative clues about the palaeoecology of this top predator from the late Miocene, and open new intriguing research horizons concerning the macroraptorial physeteroids and their trophic role in the Miocene global ocean. ...
Differing from the extant physeteroids, macroraptorial sperm whales are currently regarded as apex predators of the Miocene seas based on several morphofunctional observations. Here, we estimate the bite force of Zygophyseter varolai, a macroraptorial physeteroid from lower upper Miocene strata of the Pietra leccese formation (Apulia, Italy) using the finite element analysis (FEA). To explore multiple bite scenarios, we set four different load cases on a 3D model of the cranium obtained via digital photogram-metry, considering the temporalis and masseter muscles as jaw adductors. Our FEA simulations indicate that Z. varolai exerted an anterior bite force of more than 4000 N and a posterior bite force of more than 10000 N. These values are similar to those estimated for other marine predators known for their powerful bite. This suggests that Z. varolai might have fed upon medium-sized marine vertebrates like other odontocetes. Considering the significant difference observed between the anterior and posterior bite forces, Z. varolai likely fed via 'grip-and-shear' feeding, snapping the food items with an anterior bite and then cutting them with a powerful posterior bite. Other macroraptorial sperm whales such as the roughly coeval Acrophyseter from Peru likely employed the same feeding technique. ARTICLE HISTORY
... Finite element analysis (FEA) is an in silico technique that provides an alternative to strain gauge measurements when investigating how the cranium deforms under certain loading conditions. FEA has been used to analyse cranial stresses and strains resulting from masticatory loads in a wide range of taxa [26][27][28][29][30][31][32][33][34][35] . In addition, FEA can be integrated with multi-body dynamic analysis (MDA) to inform the FEA with kinetic data associated with various forms of mastication 29,34,36,37 . ...
... A similar process was also used to determine and visualise the dominant principal strains over all bites. The FE analyses were evaluated by considering von Mises strain because it has been employed previously to assess skull biomechanics 29,31,35,54 . In addition, von Mises strain is convenient because it is a scalar function combining the three principal strains, is related to the von Mises failure criterion, and is useful for comparing the performance of complex three-dimensional geometries. ...
Although a functional relationship between bone structure and mastication has been shown in some regions of the rabbit skull, the biomechanics of the whole cranium during mastication have yet to be fully explored. In terms of cranial biomechanics, the rabbit is a particularly interesting species due to its uniquely fenestrated rostrum, the mechanical function of which is debated. In addition, the rabbit processes food through incisor and molar biting within a single bite cycle, and the potential influence of these bite modes on skull biomechanics remains unknown. This study combined the in silico methods of multi-body dynamics and finite element analysis to compute musculoskeletal forces associated with a range of incisor and molar biting, and to predict the associated strains. The results show that the majority of the cranium, including the fenestrated rostrum, transmits masticatory strains. The peak strains generated over all bites were found to be attributed to both incisor and molar biting. This could be a consequence of a skull shape adapted to promote an even strain distribution for a combination of infrequent incisor bites and cyclic molar bites. However, some regions, such as the supraorbital process, experienced low peak strain for all masticatory loads considered, suggesting such regions are not designed to resist masticatory forces.
... There are several different approaches that have been applied to analyze the results derived from mandibular mechanics. While some works analyze stress (Attard et al. 2014, Püschel & Sellers 2016, Tseng et al. 2017, other focus on strain (Gröning et al. 2013, Oldfield et al. 2012, . When using linear and elastic properties, it has been shown that both values are proportional and that the results of the distributions along the mandible are the same. ...
... Other authors (Attard et al. 2011) studied the biomechanical performance of the skull and mandible of T. cynocephalus in relation to those of two extant marsupial carnivores with known diets that occurred sympatrically -the Tasmanian devil, Sarcophilus harrisii, and the spotted-tailed quoll, Dasyurus maculatus -suggesting that T. cynocephalus is likely to have consumed smaller prey compared to its size. Oldfield et al. (2012) created several FEA models of ursids to predict the feeding behavior of the extinct Agriotherium africanum. According to these authors, the findings did not resolve whether the fossil was more likely a predator or a scavenger of large terrestrial vertebrates but showed that it was well adapted to resist the forces generated by either activity. ...
... monspessulanus (see Valenciano and Govender, 2020). Additionally, some ecological and biomechanical studies have been performed (Werdelin, 2006;Stynder, 2009;Tseng and Stynder, 2011;Oldfield et al., 2012;Stynder et al. 2012Stynder et al. , 2018Hartstone-Rose and Stynder 2013;Stynder and Kupczik, 2013;Hartstone-Rose et al., 2016). ...
We describe abundant new remains of the medium-sized mustelid Mellivora benfieldi from the early Pliocene site of Langebaanweg (South Africa). The specimens are from the Muishond Fontein Pelletal Phosphorite Member (MPPM) and the Langeberg Quartz Sand Member (LQSM). Novel dentognathic-upper dentition, alveolus for m2-and postcranial-humerus, metacarpal V, femur and calcaneus-information is provided. This sample enables us to review the taxonomic status of Mio-Pliocene African mellivorines. Mellivora benfieldi is distinguished from the middle-late Miocene 'Eomellivora' tugenensis from Ngorora Kenya by its smaller size, and a M1 protocone messially placed; from the late Miocene Howellictis valentini from Chad by greater dental size with more crowded lower premolars, and p3 with distal accessory cuspid; and from the late Miocene Erokomellivora lothagamensis from Kenya, by shorter p4 and buccolingually shorter m1 protoconid. It also differs from H. valentini and Er. lothagamensis in absence or residual presence of the m2 alveolus. We infer M. benfieldi was an opportunistic, medium-sized carnivoran with semifossorial abilities, comparable to its living relative Mellivora capensis. A cladistic analysis was performed and our phylogenetic results place M. benfieldi as the sister species of M. capensis. Mellivorini contains M. benfieldi, M. capensis, and H. valentini. Additionally, we also include Er. lothagamensis and the Indian Promellivora punjabiensis. We propose the creation of one new tribe within Mellivorinae: Eomellivorini (Eomellivora spp. + Ekorus). It shares a common ancestor with Mellivorini and is characterized by large size, a robust and sharp dentition, as well as a skeleton with cursorial adaptations.
... FEA results suggest that the presence of a sagittal crest can affect both the energy efficiency (the amount of deformation) and strength (measured by stress) of the cranium in tapirs as it does in carnivorans 36,60,69 . The tapir with the most pronounced sagittal crest (T. ...
Paleontologists and paleoanthropologists have long debated relationships between cranial morphology and diet in a broad diversity of organisms. While the presence of larger temporalis muscle attachment area (via the presence of sagittal crests) in carnivorans is correlated with durophagy (i.e. hard-object feeding), many primates with similar morphologies consume an array of tough and hard foods—complicating dietary inferences of early hominins. We posit that tapirs, large herbivorous mammals showing variable sagittal crest development across species, are ideal models for examining correlations between textural properties of food and sagittal crest morphology. Here, we integrate dietary data, dental microwear texture analysis, and finite element analysis to clarify the functional significance of the sagittal crest in tapirs. Most notably, pronounced sagittal crests are negatively correlated with hard-object feeding in extant, and several extinct, tapirs and can actually increase stress and strain energy. Collectively, these data suggest that musculature associated with pronounced sagittal crests—and accompanied increases in muscle volume—assists with the processing of tough food items in tapirs and may yield similar benefits in other mammals including early hominins.
