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Gilbert MM, Snively E, Cotton J. The Tarsometatarsus of the Ostrich Struthio camelus: Anatomy, Bone Densities, and Structural Mechanics. PLoS One 2016; 11:e0149708. [PMID: 27015416 PMCID: PMC4807808 DOI: 10.1371/journal.pone.0149708] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 02/04/2016] [Indexed: 12/02/2022] Open
Abstract
Background The ostrich Struthio camelus reaches the highest speeds of any extant biped, and has been an extraordinary subject for studies of soft-tissue anatomy and dynamics of locomotion. An elongate tarsometatarsus in adult ostriches contributes to their speed. The internal osteology of the tarsometatarsus, and its mechanical response to forces of running, are potentially revealing about ostrich foot function. Methods/Principal Findings Computed tomography (CT) reveals anatomy and bone densities in tarsometatarsi of an adult and a young juvenile ostrich. A finite element (FE) model for the adult was constructed with properties of compact and cancellous bone where these respective tissues predominate in the original specimen. The model was subjected to a quasi-static analysis under the midstance ground reaction and muscular forces of a fast run. Anatomy–Metatarsals are divided proximally and distally and unify around a single internal cavity in most adult tarsometatarsus shafts, but the juvenile retains an internal three-part division of metatarsals throughout the element. The juvenile has a sparsely ossified hypotarsus for insertion of the m. fibularis longus, as part of a proximally separate third metatarsal. Bone is denser in all regions of the adult tarsometatarsus, with cancellous bone concentrated at proximal and distal articulations, and highly dense compact bone throughout the shaft. Biomechanics–FE simulations show stress and strain are much greater at midshaft than at force applications, suggesting that shaft bending is the most important stressor of the tarsometatarsus. Contraction of digital flexors, inducing a posterior force at the TMT distal condyles, likely reduces buildup of tensile stresses in the bone by inducing compression at these locations, and counteracts bending loads. Safety factors are high for von Mises stress, consistent with faster running speeds known for ostriches. Conclusions/Significance High safety factors suggest that bone densities and anatomy of the ostrich tarsometatarsus confer strength for selectively critical activities, such as fleeing and kicking predators. Anatomical results and FE modeling of the ostrich tarsometatarsus are a useful baseline for testing the structure’s capabilities and constraints for locomotion, through ontogeny and the full step cycle. With this foundation, future analyses can incorporate behaviorally realistic strain rates and distal joint forces, experimental validation, and proximal elements of the ostrich hind limb.
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Affiliation(s)
- Meagan M. Gilbert
- Department of Geological Sciences, University of Saskatchewan, Saskatoon, SK, Canada
- * E-mail:
| | - Eric Snively
- Department of Biology, University of Wisconsin-La Crosse, La Crosse, WI, United States of America
| | - John Cotton
- Mechanical Engineering and Biomedical Engineering, Russ College of Engineering and Technology, Ohio University, Athens, OH, United States of America
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Smith AL, Benazzi S, Ledogar JA, Tamvada K, Smith LCP, Weber GW, Spencer MA, Dechow PC, Grosse IR, Ross CF, Richmond BG, Wright BW, Wang Q, Byron C, Slice DE, Strait DS. Biomechanical implications of intraspecific shape variation in chimpanzee crania: moving toward an integration of geometric morphometrics and finite element analysis. Anat Rec (Hoboken) 2015; 298:122-44. [PMID: 25529239 PMCID: PMC4274755 DOI: 10.1002/ar.23074] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Accepted: 10/11/2014] [Indexed: 11/05/2022]
Abstract
In a broad range of evolutionary studies, an understanding of intraspecific variation is needed in order to contextualize and interpret the meaning of variation between species. However, mechanical analyses of primate crania using experimental or modeling methods typically encounter logistical constraints that force them to rely on data gathered from only one or a few individuals. This results in a lack of knowledge concerning the mechanical significance of intraspecific shape variation that limits our ability to infer the significance of interspecific differences. This study uses geometric morphometric methods (GM) and finite element analysis (FEA) to examine the biomechanical implications of shape variation in chimpanzee crania, thereby providing a comparative context in which to interpret shape-related mechanical variation between hominin species. Six finite element models (FEMs) of chimpanzee crania were constructed from CT scans following shape-space Principal Component Analysis (PCA) of a matrix of 709 Procrustes coordinates (digitized onto 21 specimens) to identify the individuals at the extremes of the first three principal components. The FEMs were assigned the material properties of bone and were loaded and constrained to simulate maximal bites on the P(3) and M(2) . Resulting strains indicate that intraspecific cranial variation in morphology is associated with quantitatively high levels of variation in strain magnitudes, but qualitatively little variation in the distribution of strain concentrations. Thus, interspecific comparisons should include considerations of the spatial patterning of strains rather than focus only on their magnitudes.
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Affiliation(s)
- Amanda L. Smith
- Department of Anthropology, University at Albany, 1400 Washington Avenue, Albany, NY, 12222, USA
| | - Stefano Benazzi
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz, 6 04103 Leipzig, Germany
- Department of Cultural Heritage, University of Bologna, Via degli Ariani 1, Ravenna 48121, Italy
| | - Justin A. Ledogar
- Department of Anthropology, University at Albany, 1400 Washington Avenue, Albany, NY, 12222, USA
| | - Kelli Tamvada
- Department of Anthropology, University at Albany, 1400 Washington Avenue, Albany, NY, 12222, USA
| | - Leslie C. Pryor Smith
- Department of Biomedical Sciences, Texas A & M University Baylor College of Dentistry, 3302 Gaston Avenue, Dallas, TX, 75246, USA
| | - Gerhard W. Weber
- Department of Anthropology, University of Vienna, Althanstr. 14, A-1090 Vienna, Austria
| | - Mark A. Spencer
- School of Human Evolution and Social Change, Arizona State University, Box 874101, Tempe, AZ, 85287-4104
- Biology, South Mountain Community College, 7050 S. 24 Street, Phoenix, AZ, 85042
| | - Paul C. Dechow
- Department of Biomedical Sciences, Texas A & M University Baylor College of Dentistry, 3302 Gaston Avenue, Dallas, TX, 75246, USA
| | - Ian R. Grosse
- Department of Mechanical & Industrial Engineering, University of Massachusetts, 160 Governor's Drive, Amherst, MA, 01003-2210
| | - Callum F. Ross
- Department of Organismal Biology & Anatomy, University of Chicago, 1027 East 57th 30 Street, Chicago, IL, 60637, USA
| | - Brian G. Richmond
- Center for the Advanced Study of Hominid Paleobiology, Department of Anthropology, The George Washington University, 2110 G St. NW, Washington, D. C., 20052, USA
- Human Origins Program, National Museum of Natural History, Smithsonian Institution, Washington, D. C., 20560, USA
- Division of Anthropology, American Museum of Natural History, Central Park West at 79 Street, New York, NY 10024-5192
| | - Barth W. Wright
- Department of Anatomy, Kansas City University of Medicine and Biosciences, 1750 Independence Avenue, Kansas City, MO, 64106-1453, USA
| | - Qian Wang
- Division of Basic Medical Sciences, Mercer University School of Medicine, 1550 College Street, Macon, GA, 31207, USA
| | - Craig Byron
- Department of Biology, Mercer University, 1400 Coleman Avenue, Macon, GA, 31207, USA
| | - Dennis E. Slice
- Department of Anthropology, University of Vienna, Althanstr. 14, A-1090 Vienna, Austria
- School of Computational Science & Department of Biological Science, Florida State University, Dirac Science Library, Tallahassee, FL, 32306-4120
| | - David S. Strait
- Department of Anthropology, University at Albany, 1400 Washington Avenue, Albany, NY, 12222, USA
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