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Comparison of dental measurement systems for taxonomic assignment of first molars

Authors

  • Stefano Benazzi,

    Corresponding author
    1. Department of Anthropology, University of Vienna, Vienna 1090, Austria
    2. Department of Palaeoanthropology and Messel Research, Senckenberg Research Institute, Frankfurt am Main D-60325, Germany
    • Department of Anthropology, University of Vienna, Althanstraße 14, 1090 Vienna, Austria
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  • Michael Coquerelle,

    1. Department of Anthropology, University of Vienna, Vienna 1090, Austria
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  • Luca Fiorenza,

    1. Department of Palaeoanthropology and Messel Research, Senckenberg Research Institute, Frankfurt am Main D-60325, Germany
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  • Fred Bookstein,

    1. Department of Anthropology, University of Vienna, Vienna 1090, Austria
    2. Department of Statistics, University of Washington, Seattle, WA 98195
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  • Stanislav Katina,

    1. Department of Applied Mathematics and Statistics, Comenius University, Bratislava 842 48, Slovakia
    2. Department of Statistics, University of Glasgow, Glasgow, Scotland G12 8QQ, United Kingdom
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  • Ottmar Kullmer

    1. Department of Palaeoanthropology and Messel Research, Senckenberg Research Institute, Frankfurt am Main D-60325, Germany
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Abstract

Morphometrics of the molar crown is based traditionally on diameter measurements but is nowadays more often based on 2D image analysis of crown outlines. An alternative approach involves measurements at the level of the cervical line. We compare the information content of the two options in a three-dimensional (3D) digital sample of lower and upper first molars (M1 and M1) of modern human and Neanderthal teeth. The cervical outline for each tooth was created by digitizing the cervical line and then sectioning the tooth with a best fit plane. The crown outline was projected onto this same plane. The curves were analyzed by direct extraction of diameters, diagonals, and area and also by principal component analysis either of the residuals obtained by regressing out these measurements from the radii (shape information) or directly by the radii (size and shape information). For M1, the crown and cervical outline radii allow us to discriminate between Neanderthals and modern humans with 90% and 95% accuracy, respectively. Fairly good discrimination between the groups (80–82.5%) was also obtained using cervical measurements. With respect to M1, general overlap of the two groups was obtained by both crown and cervical measurements; however, the two taxa were differentiable by crown outline residuals (90–97%). Accordingly, while crown diameters or crown radii should be used for taxonomic analysis of unworn or slightly worn M1s, the crown outline, after regressing out size information, could be promising for taxonomic assignment of lower M1s. Am J Phys Anthropol, 2011. © 2010 Wiley-Liss, Inc.

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