Technical note: Morphometric maps of long bone shafts and dental roots for imaging topographic thickness variation

Abstract

Qualitative and quantitative characterization through functional imaging of mineralized tissues is of potential value in the study of the odontoskeletal remains. This technique, widely developed in the medical field, allows the bi-dimensional, planar representation of some local morphometric properties, i.e., topographic thickness variation, of a three-dimensional object, such as a long bone shaft. Nonetheless, the use of morphometric maps is still limited in (paleo)anthropology, and their feasibility has not been adequately tested on fossil specimens. Using high-resolution microtomographic images, here we apply bi-dimensional virtual ''unrolling'' and synthetic thickness mapping techniques to compare cortical bone topographic variation across the shaft in a modern and a fossil human adult femur (the Magdalenian from Chancelade). We also test, for the first time, the possibility to virtually unroll and assess for dentine thickness variation in modern and fossil (the Neanderthal child from Roc de Marsal) human deciduous tooth roots. The analyses demonstrate the feasibility of using two-dimensional morphometric maps for the synthetic functional imaging and comparative biomechanical interpretation of cortical bone thickness variation in extant and fossil specimens and show the interest of using this technique also for the subtle characterization of root architecture and dentine topography. More specifically, our preliminary results support the use of virtual cartography as a tool for assessing to what extent internal root morphology is capable of responding to loading and directional stresses and strains in a predictable way. Am J Phys Anthropol 142:328-334, 2010. V V C 2010 Wiley-Liss, Inc.

Three-dimensional computer-assisted craniometrics: A comparison of the uncertainty in measurement induced by surface reconstruction performed by two computer programs

“…AMIRA (Mercury computer systems, Berlin, Germany) is a 3D modelling and visualisation system widely used for observation and quantification in several scientific disciplines [23][24][25] and physical anthropology [26][27][28][29][30][31][32][33][34][35][36]. It offers two kinds of surface extraction: one using an isosurface algorithm and the other using a segmented surface algorithm.…”

Phenotypic Variation in Infants, Not Adults, Reflects Genotypic Variation among Chimpanzees and Bonobos

“…MM is a landmark-free geometric morphometric method that permits dense sampling of data from smooth surfaces. It is thus well suited to quantify even subtle morphological differences in femoral shaft form between different taxa and/or developmental stages [87], [91], [92], [93]. To correct for size differences between specimens, size is normalized by diaphyseal length and the median value of the radius of curvature.…”

Is the deciduous/permanent molar enamel thickness ratio a taxon-specific indicator in extant and extinct hominids?

“…To visualize similarities vs. differences in enamel thickness topography within an assemblage of such variably sized and shaped teeth, ad hoc imaging techniques were used to virtually unroll lateral enamel and to project it into standardized morphometric maps Bondioli et al, 2010;Macchiarelli et al, 2013; for similar imaging techniques, see also Dowdeswell et al, 2017;Morita et al, 2016Morita et al, , 2017Puymerail, 2011;Puymerail et al, 2012aPuymerail et al, , 2012bTsegai et al, 2017). Because each morphometric map (MM) is scaled according to the maximal value of the analysed tooth, the patterns expressed by the dm2s and the M1s are independent from the absolute and relative enamel thickness values.…”