Download Three-dimensional analysis of temporal bone microstructure in P

Three-dimensional analysis of temporal bone pneumatization patterns in olive
baboons.
Cheryl A. Hill. Department of Anthropology, Pennsylvania State University.
While most cercopithecines lack paranasal sinuses, extensive pneumatization is
present in the baboon temporal bone. Since pneumatization is used as a character in
phylogenetic analysis, understanding normal patterns of morphological variation and
symmetry in temporal bone pneumatization is necessary. This study is a portion of a
larger investigation of evolutionary change in pneumatization patterns in the
cercopithecine lineage.
The study sample consists of the skulls of female (N=20) and male (N=5) adult
Papio hamadryas anubis specimens. High resolution computed tomography scans
were acquired from left and right temporal bones for each specimen with slice
thicknesses approximating 70 microns. Using Amira, surface areas and volumes of
pneumatized spaces were collected from the entire temporal bone and specific regions
within the temporal bone. Spherical volumes of interest were cropped from specific
regions using Quant3D software and analyzed for bone volume fractions and anisotropy
using the star volume distribution method.
Results indicate that bony struts within pneumatized regions of baboon temporal
bones tend towards isotropy. This pattern is unlike those recorded for extant African ape
species showing anisotropy of bony struts indicative of localized biomechanical
necessity. The tendency towards isotropy in P. h. anubis demonstrates that
biomechanical requirements in the baboon temporal are not unidirectional and suggests
biomechanical patterns for baboon temporal bones differ from those characteristic of
other African ape species . Moreover, these results suggest that patterns of
organization and structure of pneumatized spaces in the temporal bone can be used to
differentiate P. h. anubis from other primate species.
This project was supported in part by NSF (BCS-052493, BCS-0523637), the Leakey
Foundation, and Pennsylvania State University (Hill Foundation and Baker Fund).