title: The Biomechanics of Bony Facial "Buttresses" in South African Australopiths: An Experimental Study Using Finite Element Analysis.
abstract: Australopiths exhibit a number of derived facial features that are thought to strengthen the face against high and/or repetitive loads associated with a diet that included mechanically challenging foods. Here, we use finite element analysis (FEA) to test hypotheses related to the purported strengthening role of the zygomatic root and "anterior pillar" in australopiths. We modified our previously constructed models of Sts 5 (Australopithecus africanus) and MH1 (A. sediba) to differ in the morphology of the zygomatic root, including changes to both the shape and positioning of the zygomatic root complex, in addition to creating variants of Sts 5 lacking anterior pillars. We found that both an expanded zygomatic root and the presence of "anterior pillars" reinforce the face against feeding loads. We also found that strain orientations are most compatible with the hypothesis that the pillar evolved to resist loads associated with premolar loading, and that this morphology has an ancillary effect of strengthening the face during all loading regimes. These results provide support for the functional hypotheses. However, we found that an anteriorly positioned zygomatic root increases strain magnitudes even in models with an inflated/reinforced root complex. These results suggest that an anteriorly placed zygomatic root complex evolved to enhance the efficiency of bite force production while facial reinforcement features, such as the anterior pillar and the expanded zygomatic root, may have been selected for in part to compensate for the weakening effect of this facial configuration. Anat Rec, 300:171-195, 2017. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Zoology Division, School of Environmental and Rural Science, University of New England, Armidale, NSW, 2351, Australia.|Department of Anthropology, University at Albany, Albany, New York.
authors.forename: Justin A
authors.initials: JA
authors.lastname: Ledogar
authors.affiliation: Department of Cultural Heritage, University of Bologna, Ravenna, 48121, Italy.|Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, 04103, Germany.
authors.forename: Stefano
authors.initials: S
authors.lastname: Benazzi
authors.affiliation: Department of Anthropology, University at Albany, Albany, New York.|Department of Anthropology, Washington University in St. Louis, St. Louis, Missouri.
authors.forename: Amanda L
authors.initials: AL
authors.lastname: Smith
authors.affiliation: Department of Anthropology, University of Vienna, Vienna, A-1090, Austria.
authors.forename: Gerhard W
authors.initials: GW
authors.lastname: Weber
authors.affiliation: Department of Anthropology, Texas A&M University, College Station, Texas.
authors.forename: Keely B
authors.initials: KB
authors.lastname: Carlson
authors.affiliation: School of Science and Mathematics, Abraham Baldwin Agricultural College, Tifton, Georgia 30605.
authors.forename: Paul C
authors.initials: PC
authors.lastname: Dechow
authors.affiliation: Department of Mechanical and Industrial Engineering, University of Massachusetts, Amherst, Massachusetts.
authors.forename: Ian R
authors.initials: IR
authors.lastname: Grosse
authors.affiliation: Department of Organismal Biology and Anatomy, University of Chicago, Chicago, Illinois.
authors.forename: Callum F
authors.initials: CF
authors.lastname: Ross
authors.affiliation: Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, 04103, Germany.|Division of Anthropology, American Museum of Natural History, New York, New York.
authors.forename: Brian G
authors.initials: BG
authors.lastname: Richmond
authors.affiliation: Department of Anatomy, Kansas City University of Medicine and Biosciences, Kansas City, Missouri.
authors.forename: Barth W
authors.initials: BW
authors.lastname: Wright
authors.affiliation: School of Science and Mathematics, Abraham Baldwin Agricultural College, Tifton, Georgia 30605.
authors.forename: Qian
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Department of Biology, Mercer University, Macon, Georgia.
authors.forename: Craig
authors.initials: C
authors.lastname: Byron
authors.affiliation: Department of Cell and Neurobiology, Keck School of Medicine, University of Southern California, Los Angeles, California.|Evolutionary Studies Institute, University of the Witwatersrand, Wits, 2050, South Africa.
authors.forename: Kristian J
authors.initials: KJ
authors.lastname: Carlson
authors.affiliation: Department of Anthropology, Texas A&M University, College Station, Texas.|Evolutionary Studies Institute, University of the Witwatersrand, Wits, 2050, South Africa.
authors.forename: Darryl J
authors.initials: DJ
authors.lastname: De Ruiter
authors.affiliation: School of Science and Mathematics, Abraham Baldwin Agricultural College, Tifton, Georgia 30605.
authors.forename: Leslie C
authors.initials: LC
authors.lastname: Pryor Mcintosh
authors.affiliation: Department of Anthropology, University at Albany, Albany, New York.|Department of Anthropology, Washington University in St. Louis, St. Louis, Missouri.
authors.forename: David S
authors.initials: DS
authors.lastname: Strait
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena / Q000502:physiology; D001732:Bite Force; D004032:Diet; D005247:Feeding Behavior / Q000502:physiology; D020342:Finite Element Analysis; D015186:Hominidae / Q000033:anatomy & histology* / Q000502:physiology*; D008409:Mastication / Q000502:physiology*; D008962:Models, Theoretical; D012886:Skull / Q000033:anatomy & histology / Q000502:physiology*; D015050:Zygoma / Q000033:anatomy & histology / Q000502:physiology*
keywords: evolution; function; zygoma