Computerized restoration of nonhomogeneous deformation of a fossil cranium based on bilateral symmetry

Authors

  • Naomichi Ogihara,

    Corresponding author
    1. Laboratory of Physical Anthropology, Department of Zoology, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
    • Laboratory of Physical Anthropology, Department of Zoology, Graduate School of Science, Kyoto University, Kitashirakawa-oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan
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  • Masato Nakatsukasa,

    1. Laboratory of Physical Anthropology, Department of Zoology, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
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  • Yoshihiko Nakano,

    1. Laboratory of Biological Anthropology, Graduate School of Human Sciences, Osaka University, Suita, Osaka 565-0871, Japan
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  • Hidemi Ishida

    1. School of Human Nursing, University of Shiga Prefecture, Hikone, Shiga 522-8533, Japan
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Abstract

We developed a computerized method of correcting plastic deformation of a fossil skull, based on bilateral symmetry with respect to the midsagittal plane, and applied this method to reconstruction of a fossilized Proconsul heseloni cranium (KNM-RU-7290A). A three-dimensional (3D) model of the fossil was generated using consecutive cross-sectional images retrieved from computed tomography. 3D coordinates of anatomical landmarks that should be located on the midsagittal plane and pairs of landmarks that should be symmetrical with respect to this plane were acquired. These landmarks were then repositioned so that geometrical constraints were satisfied, while translated distances of landmarks were minimized. We adopted a thin-plate spline function to mathematically describe the 3D nonlinear volumetric transformation between acquired and repositioned landmarks. Using this function, the entire fossil shape was transformed, and the effect of reversing the deformation could be visualized. The results indicated that the proposed method was effective in eliminating nonhomogeneous deformation of the fossil skull. The antemortem appearance of the skull cannot be completely restored by this method alone, due to methodological limitations. However, the presented method has a role as an adjunct in complementing conventional restoration techniques on account of its objective nature. Am J Phys Anthropol, 2006. © 2005 Wiley-Liss, Inc.

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