What is the advantage of CT?

1) The resolution possible from CT scanners currently available is significantly finer than the degree of accuracy obtainable from direct measurements of the original specimen using calipers.  Combined with 3D visualization software currently available, it is possible to take any linear measurement from the CT scans themselves that one can make on the actual specimen.  This means that for a large number of research questions, specimens never have to be touched again, thereby minimizing the likelihood that they will be damaged (some of the bones of the skull are extremely thin and easily broken even when handled with care).  It also means that, given the appropriate hardware and software, research on these specimens can be done anywhere. For many research questions, it would not be necessary for the researcher to actually physically visit the museum housing the specimens.

2) Using CT scans it is possible to reconstruct internal structures that are not easily studied (or are impossible to study) externally.  Studies of the evolution of bipedalism have included analyses of the orientation of the inner ear, for example.  Without CT, this would not be possible without damaging specimens.

3) Recent advances in 3D image analysis for clinical research allow for new and more powerful studies of complex geometry of the skull.  For example, algorithms that allow several brains to be transformed (morphed) into a common coordinate system have been developed for use in functional brain imaging, to allow more accurate comparison of brain activation across individuals with brains of different sizes and shapes.  We have begun applying these algorithms to create high resolution 3D maps of individual variability in morphology.  This information (routinely discarded in functional imaging studies once individual functional scans are morphed into the same brain space) is an extremely rich source of information that can be used to study shape in much more sophisticated ways than has been possible previously.