Allometric shape vector projection: A new method for the identification of allometric shape characters and trajectories applied to the human astragalus (talus)

Research Department of Genetics, Evolution and Environment, Division of Biosciences, University College London, London, UK.
Journal of Theoretical Biology (Impact Factor: 2.12). 03/2011; 272(1):64-71. DOI: 10.1016/j.jtbi.2010.11.030
Source: PubMed


The surface morphology of the human astragalus (talus) is difficult to represent accurately using landmarks as it is essentially globular in shape. Advances in laser scanning technology allow fast and accurate capture of bone surface morphology. However, methodologies to utilise these new accurate 3D data have not been fully developed. The present study uses canonical sampling of whole surface morphology attained through laser scanning and for the first time applies the technique to analysis of bone morphology. We introduce a new technique for identifying allometric shape characters in whole bone surface morphology. In a sample of adult human astragalus the new technique is successful in identifying and isolating intra-specific allometric shape characters in a bone which typically lacks landmarks and has, consequently, proved difficult to analyse using traditional 3D morphometric methods.

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    • "The canonical sampling process (Douros et al. 2002; Buxton et al. 2003; Ruto et al. 2006; Ruto, 2009) gives an accurate representation of the whole talar surface morphology, and the resulting surface models were used in a PCA of whole talar shapes (following Parr et al. 2011a). The canonical sampling procedure used here is similar to the eigensurface method described by Polly & Macleod (2008) where the surface points per slice (50 slices) were obtained by projecting radii from the major axis at equally spaced angles (360 o /50). "
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    • "Non-landmark based three-dimensional methods offer a means to quantify hip joint size in fragmentary fossils that avoids the need for the preservation of a complete acetabulum or femoral head. Three-dimensional digital morphometric analysis using reconstructed surface or sectional scan data and automated design software has emerged as a tool for quantitative analysis (Tocheri et al., 2003, 2005, 2007; Harcourt-Smith et al., 2008; Parr et al., 2011; Garvin and Ruff, 2012). Due to the spherical shape of the femoral head and acetabulum, the hip joint is an excellent candidate for the application of least squares best-fit sphere-fitting techniques using automated design software to quantify joint size (Hammond et al., 2010b, 2012; Plavcan et al., 2012). "
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