Morphometric estimation of torsional stiffness and strength in primate mandibles

Daegling, David J.

doi:10.1002/ajpa.20508

Cited by 25 publications

(15 citation statements)

References 30 publications

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“…A deep corpus represents an efficient means by which to resist parasagittal bending, whereas a transversely thick corpus is usually represented in the comparative literature as an effective means to resist torsional loads. The wisdom of this latter premise has been called into question (Daegling and Hylander, 1998), and within narrow allometric ranges (such as in the samples examined here) it may not reflect torsional stiffness and strength in predictable ways (Daegling, 2007). It is more certain, however, that increases in cross-sectional area represent effective strategies for countering torsional loads.…”

Section: Discussionmentioning

confidence: 86%

Functional morphology of the mangabey mandibular corpus: Relationship to dental specializations and feeding behavior

Daegling

McGraw

2007

American J Phys Anthropol

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Recent molecular and morphological surveys suggest that mangabeys do not represent a monophyletic group. Specifically, Cercocebus is the sister taxon of Mandrillus, whereas Lophocebus forms an unresolved trichotomy with Papio and Theropithecus. The Cercocebus-Mandrillus clade is characterized by skeletal and dental adaptations related to acquisition and processing of hard-object foods that resist decomposition for months on the forest floor. Although species of both mangabey genera can be described as frugivorous seed predators with a strong reliance on hard-object foods, a growing body of evidence indicates that Cercocebus (terrestrial) and Lophocebus (arboreal) mangabeys differ in the hardness of the seeds they consume and the manner in which seeds are processed. The taxa are also distinguished on the basis of dental morphology. Given the purported differences in feeding behaviors of the two mangabey genera, we consider whether there are predictable biomechanical consequences of these behaviors that are reflected in mandibular corpus dimensions. In addition, we present metric data summarizing functional aspects of mangabey mandibular corpus morphology. Mangabey genera are generally not distinguished by differences in relative corpus size, either in postcanine or symphyseal regions. Distinct symphyseal scaling patterns characterize the Papio-Lophocebus clade and the Mandrillus-Cercocebus clade, while the postcanine corpus scales similarly between them. The hypothesis that preferential use of the incisors vs. premolars to initially process these foods results in distinct stress environments is weakly supported, given circumstantial evidence that the relative importance of bending vs. torsion may differ between Cercocebus and Lophocebus.

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Section: Discussionmentioning

confidence: 86%

Functional morphology of the mangabey mandibular corpus: Relationship to dental specializations and feeding behavior

Daegling

McGraw

2007

American J Phys Anthropol

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Section: Hypothesesmentioning

confidence: 99%

“…The simple torsion formula cannot be applied to noncircular, hollow cross sections, such as mandibles, and other methods must be used (Daegling,1989,2002,2007a,b; Daegling and Hylander,1998). Various formulae can be used to account for eccentricity of the ellipse and wall thickness (Roark and Young,1975), but all these formulae are approximations (Daegling and Hylander,1998; Daegling,2007a; Ameen,2008). Indeed, the applicability of elliptical models is not supported by empirical observation (Daegling,1989) and even elliptical models with nonuniform wall thicknesses (Biknevicius and Ruff,1992) “impose a geometric regularity to (mandibular) corpus shape that is rarely observed in nature” (Daegling and Hylander,1998).…”

Section: Hypothesesmentioning

confidence: 99%

Free body analysis, beam mechanics, and finite element modeling of the mandible of Alligator mississippiensis

Porro

Holliday

Anapol

et al. 2011

Journal of Morphology

140

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The mechanical behavior of mammalian mandibles is well-studied, but a comprehensive biomechanical analysis (incorporating detailed muscle architecture, accurate material properties, and three-dimensional mechanical behavior) of an extant archosaur mandible has never been carried out. This makes it unclear how closely models of extant and extinct archosaur mandibles reflect reality and prevents comparisons of structure-function relationships in mammalian and archosaur mandibles. We tested hypotheses regarding the mechanical behavior of the mandible of Alligator mississippiensis by analyzing reaction forces and bending, shear, and torsional stress regimes in six models of varying complexity. Models included free body analysis using basic lever arm mechanics, 2D and 3D beam models, and three high-resolution finite element models of the Alligator mandible, incorporating, respectively, isotropic bone without sutures, anisotropic bone with sutures, and anisotropic bone with sutures and contact between the mandible and the pterygoid flange. Compared with the beam models, the Alligator finite element models exhibited less spatial variability in dorsoventral bending and sagittal shear stress, as well as lower peak values for these stresses, suggesting that Alligator mandibular morphology is in part designed to reduce these stresses during biting. However, the Alligator models exhibited greater variability in the distribution of mediolateral and torsional stresses than the beam models. Incorporating anisotropic bone material properties and sutures into the model reduced dorsoventral and torsional stresses within the mandible, but led to elevated mediolateral stresses. These mediolateral stresses were mitigated by the addition of a pterygoid-mandibular contact, suggesting important contributions from, and trade-offs between, material properties and external constraints in Alligator mandible design. Our results suggest that beam modeling does not accurately represent the mechanical behavior of the Alligator mandible, including important performance metrics such as magnitude and orientation of reaction forces, and mediolateral bending and torsional stress distributions. J.Morphol. 2011. © 2011 Wiley-Liss, Inc.

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“…Beecher, 1979;Hylander, 1985Hylander, , 1988Bouvier, 1986;Daegling, 1992Daegling, , 2007Anton, 1996;Ravosa, 1996Ravosa, , 2000Daegling and Hylander, 1998;Vinyard and Ravosa, 1998;Taylor, 2006a, b;Daegling and Grine, 2007). However, the results of these studies did not always conform to the expected patterns of covariance between mandibular morphology and masticatory loads, and it has been suggested that biomechanical factors alone cannot explain variation in corpus dimensions and proportions (e.g.…”

Section: Introductionmentioning

confidence: 99%

Influence of size and placement of developing teeth in determining anterior corpus height in prehistoric Jomon and modern Japanese mandibles

Fukase

Suwa

2010

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The juvenile mandible of the modern Japanese has a lower symphysis than that of the prehistoric Jomon, while the adult symphysis is conversely higher in the modern Japanese. This cannot be explained from population differences in masticatory environments. As an alternative factor that may influence symphyseal height, we examined tooth crypt size and placement patterns in the skeletal growth series of the two populations. Results showed that although the Jomon mandible had larger bicanine breadth than in the modern Japanese during growth, the modern Japanese has faster growing anterior teeth that became larger than those of the Jomon by the time of eruption, necessitating greater space. This is expressed as the faster growth rate of anterior alveolar height in the modern Japanese, measured as corpus height above the mandibular canal. Canine eruption distance and root length were greater in the modern Japanese than in the Jomon, corresponding to the increased difference of anterior corpus height between the two populations after canine eruption. However, the influence of tooth root length on anterior corpus height during later growth cannot be evaluated by this study. The present study suggests that the size and spatial dispositions of the developing anterior teeth have significant effects on symphyseal dimensions of the mandible until the time of tooth eruption.

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Morphometric estimation of torsional stiffness and strength in primate mandibles

Cited by 25 publications

References 30 publications

Functional morphology of the mangabey mandibular corpus: Relationship to dental specializations and feeding behavior

Functional morphology of the mangabey mandibular corpus: Relationship to dental specializations and feeding behavior

Free body analysis, beam mechanics, and finite element modeling of the mandible of Alligator mississippiensis

Influence of size and placement of developing teeth in determining anterior corpus height in prehistoric Jomon and modern Japanese mandibles

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