Vertebrate Synchrotron projects

This loan seeks to obtain high-resolution CT data from a variety of vertebrate specimens in care of the Wits-ESI to support student led research projects.

The first project, which will collect data for the PhD of Bailey Weiss (Wits ESI), seeks to non-destructively scan the limbs of a variety of early branching crocodylomorphs for palaeohistological reconstruction. These specimens represent either the best or the only postcranial material for their respective species, and by scanning them at high resolution we hope to obtain data suitable for reconstructing their growth history, and data suitable for imaging their ankle morphology. Growth history is poorly understood in extinct crocodylomorphs, and while living crocodiles have slow metabolic rates and slow growth, their common archosaurian ancestors had much more rapid growth and potentially higher metabolic rates. Understanding when the crocodylomorph line changed its growth patterns is therefore of macroevolutionary importance. Surprisingly, the earliest crocodylomorphs show evidence of having highly active, terrestrial lifestyles, with erect postures and running capability that is lacking in living members of the group. Our scans of the ankle of Orthosuchus in particular will be useful for understanding the mechanics of these postures because of the intrinsic role the ankle plays in terrestrial locomotion. These data are tightly linked to the understanding of growth and metabolism from the first objective, and we hope that by integrating locomotory data with growth history data, we can gain a better picture of what the life habits of the earliest crocodylomorphs were. The resolution necessary for palaeohistology (±.7 micron voxel size) precludes scanning at any facility in South Africa.

The second project seeks to image the skull of BP/1/8468, a potentially new sauropodomorph taxon from the lower Elliot Fomation. This skull has been scanned at the Wits Microfocus CT lab, but we were unable to penetrate the extremely dense matrix. These scans will be reconstructed to image each bone in three dimensions and to compare the anatomy to other, better-known Elliot sauropodomorph, especially Massospondylus carinatus.