Bone density and long bone representation in archaeological faunas: comparing results from CT and photon densitometry

Research into animal bone density has provided the foundation for the assessment of post-depositional destruction of archaeological faunal assemblages. This paper presents bone mineral density values for caprid long bones as determined by computed tomography (CT). Unlike photon densitometry, the technique employed in previous archaeological studies of bone density, CT provides precise assessments of the cross-sectional area of scan sites. Researchers using photon densitometry have been unable to factor out the marrow cavity in their determination of cross-sectional area, thereby significantly underestimating the density of long bone shafts. The density values obtained by CT are much higher, particularly for middle shaft portions, than those presented in previous studies and are more consistent with existing data on the material properties of bone. For two archaeological faunal assemblages that have been subject to post-depositional attribution, the CT density values show a much stronger correlation with long bone portion survival than those provided by photon densitometry. Given such advantages over photon densitometry, CT is a promising method for future archaeological investigations into bone density.