Precision and accuracy of acetabular size measures in fragmentary hominin pelves obtained using sphere-fitting techniques
Article first published online: 7 FEB 2013
Copyright © 2013 Wiley Periodicals, Inc.
American Journal of Physical Anthropology
Volume 150, Issue 4, pages 565–578, April 2013
How to Cite
Hammond, A. S., Plavcan, J. M. and Ward, C. V. (2013), Precision and accuracy of acetabular size measures in fragmentary hominin pelves obtained using sphere-fitting techniques. Am. J. Phys. Anthropol., 150: 565–578. doi: 10.1002/ajpa.22228
- Issue published online: 18 MAR 2013
- Article first published online: 7 FEB 2013
- Manuscript Accepted: 20 DEC 2012
- Manuscript Received: 11 JUL 2012
- National Science Foundation. Grant Number: BSC 0647557
- Wenner-Gren Foundation and LSB Leakey Foundation.
- hominin pelves;
- error study;
- laser scans
Hip joint diameter is highly correlated with body size in primates and so can potentially provide important information about the biology of fossil hominins. However, quantifying hip joint size has been difficult or impossible for many important but fragmentary specimens. New three-dimensional technologies can be used to digitally fit spheres to the acetabular lunate surface, potentially allowing hip joint diameter estimates for incomplete joint surfaces. Here we evaluate the reliability of sphere-fitting to incomplete lunate surfaces in silico using three-dimensional polygonal models of extant anthropoid hipbones. Measurement error in lunate sphere-fitting was assessed at the individual observer level, as well as between observers. Prediction error was also established for acetabular sphere size estimates for smaller divisions of the lunate surface. Sphere-fitting techniques were then applied to undistorted regions of lunate surface in Plio-Pleistocene hominin pelves, with a range of diameters constructed from extant error estimates. The results of this study indicate that digital sphere-fitting techniques are precise and that the lunate does not need to be completely preserved to accurately infer hip dimensions, although some aspects of joint size and morphology can influence sphere size estimates. Joint diameter is strongly predicted by spheres fit to the cranial and caudal halves of the lunate in all anthropoids. We present new hip joint size estimates for a number of fossil hominins, and outline additional applications for digital sphere-fitting as a morphometric technique. Am J Phys Anthropol 150:565–578, 2013. © 2013 Wiley Periodicals, Inc.