Material properties of mandibular cortical bone in the American alligator, Alligator mississippiensis

Zapata, Uriel; Metzger, Keith A.; Wang, Qian; Elsey, Ruth M.; Ross, Callum F.; Dechow, Paul C.

doi:10.1016/j.bone.2009.11.010

Cited by 41 publications

(39 citation statements)

References 48 publications

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“…This cross section was assumed to be constant along the length of the beam. Young's modulus was set at 15 GPa, the approximate mean elastic modulus of Alligator mandibular cortical bone from Zapata et al (2010).…”

Section: Methodsmentioning

confidence: 99%

“…The beam FEM is 189 mm in length, is composed of 64,071 solid hexahedral elements, and was given the same elastic modulus (15 GPa) as the Beam 2D model. Values for density (1772.6 kg/m 3 ) and Poisson's ratio (0.29) corresponding to the averages obtained for Alligator mandibular cortical bone (Zapata et al,2010) were applied. Material properties were assumed to be isotropic.…”

Section: Methodsmentioning

confidence: 99%

“…Suture reflects our current best estimate of the material properties of all the components of the Alligator mandible (Table 6). Anisotropic bone material properties are from an individual of similar size to the specimen used to construct the FEM (Zapata et al,2010). There is no published information on the material properties of crocodilian teeth, sutures, or PDL, so the teeth were assigned the material properties of bovine dentine (Gilmore et al,1969), which has been applied to other archosaur FEMs (Rayfield et al,2001).…”

Section: Methodsmentioning

confidence: 99%

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

Porro

Holliday

Anapol

et al. 2011

Journal of Morphology

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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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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

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

Porro

Holliday

Anapol

et al. 2011

Journal of Morphology

Self Cite

140

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“…A single node at the tip of the caudal tooth and a single node in the middle of the articular surface of each quadrate bone were constrained in all three translational and all three rotational degrees of freedom. Material properties of alligator mandibular cortical bone were assigned to all elements of the FEM following Zapata et al (2010). The scope of this project prohibited the inclusion of cranial sutures in the models; further, the material properties of sutures in A. mississippiensis (or indeed, the material properties of cranial sutures in any reptile) are unknown.…”

Section: Feamentioning

confidence: 99%

Ontogeny of bite force in a validated biomechanical model of the American alligator

Sellers

Middleton

Davis

et al. 2017

Journal of Experimental Biology

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Three-dimensional computational modeling offers tools with which to investigate forces experienced by the skull during feeding and other behaviors. American alligators (Alligator mississippiensis) generate some of the highest measured bite forces among extant tetrapods. A concomitant increase in bite force accompanies ontogenetic increases in body mass, which has been linked with dietary changes as animals increase in size. Because the flattened skull of crocodylians has substantial mediolaterally oriented muscles, crocodylians are an excellent model taxon in which to explore the role of mediolateral force components experienced by the feeding apparatus. Many previous modeling studies of archosaur cranial function focused on planar analysis, ignoring the mediolateral aspects of cranial forces. Here, we used three-dimensionally accurate anatomical data to resolve 3D muscle forces. Using dissection, imaging and computational techniques, we developed lever and finite element models of an ontogenetic series of alligators to test the effects of size and shape on cranial loading and compared estimated bite forces with those previously measured in vivo in A. mississippiensis. We found that modeled forces matched in vivo data well for intermediately sized individuals, and somewhat overestimated force in smaller specimens and underestimated force in larger specimens, suggesting that ontogenetically static muscular parameters and bony attachment sites alone cannot account for all the variation in bite force. Adding aponeurotic muscle attachments would likely improve force predictions, but such data are challenging to model and integrate into analyses of extant taxa and are generally unpreserved in fossils. We conclude that anatomically accurate modeling of muscles can be coupled with finite element and lever analyses to produce reliable, reasonably accurate estimate bite forces and thus both skeletal and joint loading, with known sources of error, which can be applied to extinct taxa.

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“…For the purpose of this study we have assumed that crocodilians and spinosaur theropod dinosaurs possess equivalent stiffness and shear values, and hence can be compared directly without consideration of potential differences in material properties. We will never know the exact material properties of extinct animal bone; however studies have shown that many taxonomically distinct vertebrates have similar moduli [56], and indeed there are similarities in the cranial material properties of crocodilian and mammalian bone [57].…”

Section: Discussionmentioning

confidence: 99%

Feeding Mechanics in Spinosaurid Theropods and Extant Crocodilians

Cuff

Rayfield

2013

PLoS ONE

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A number of extant and extinct archosaurs evolved an elongate, narrow rostrum. This longirostrine condition has been associated with a diet comprising a higher proportion of fish and smaller prey items compared to taxa with broader, more robust snouts. The evolution of longirostrine morphology and a bulbous anterior rosette of premaxillary teeth also occurs in the spinosaurid theropod dinosaurs, leading to suggestions that at least some members of this clade also had a diet comprising a notable proportion of fish or other small vertebrates. Here we compare the rostral biomechanics of the spinosaurs Baryonyx walkeri and Spinosaurus c.f. S. aegyptiacus to three extant crocodilians: two longistrine taxa, the African slender-snouted crocodile Mecistops cataphractus and the Indian gharial Gavialis gangeticus; and the American alligator Alligator mississippiensis.Using computed tomography (CT) data, the second moments of area and moments of inertia at successive transverse slices along the rostrum were calculated for each of the species. Size-independent results tested the biomechanical benefits of material distribution within the rostra. The two spinosaur rostra were both digitally reconstructed from CT data and compared against all three crocodilians. Results show that African slender-snouted crocodile skulls are more resistant to bending than an equivalent sized gharial. The alligator has the highest resistances to bending and torsion of the crocodiles for its size and greater than that of the spinosaurs. The spinosaur rostra possess similar resistance to bending and torsion despite their different morphologies. When size is accounted for, B. walkeri performs mechanically differently from the gharial, contradicting previous studies whereas Spinosaurus does not. Biomechanical data support known feeding ecology for both African slender-snouted crocodile and alligator, and suggest that the spinosaurs were not obligate piscivores with diet being determined by individual animal size.

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Material properties of mandibular cortical bone in the American alligator, Alligator mississippiensis

Cited by 41 publications

References 48 publications

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

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

Ontogeny of bite force in a validated biomechanical model of the American alligator

Feeding Mechanics in Spinosaurid Theropods and Extant Crocodilians

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