Computed tomography and biomechanical analysis of fossil long bones.

Computerized transverse axial scanning (computed tomography) is a relatively new radiographic technique designed to recover precise cross-sectional images (tomograms) of 3-dimensional objects. This highly sensitive process permits tissues of similar density to be separated and displayed unambiguously. These special features are, therefore, ideal for analyzing the cross-sectional geometry of intact fossil long bones, even when they are highly mineralized and their medullary cavities are occluded by matrix. In order to demonstrate the utility of this method in assessing the complex relationship between fossil structure and probable function, geometrical and biomechanical properties of midshaft tomograms of femora and tibiae have been analyzed for a comparative primate sample consisting of Megaladapis edwardsi (an extinct giant prosimian from Madagascar), Indri indri (the largest extant prosimian), and Homo sapiens.