Acknowledgements
We would like thank NECSA (South African Nuclear Energy Corporation SOC Limited) and specifically the RADTOM-team (Kobus Hoffman & Frikkie de Beer) for dedication and time invested for the free scanning of the skulls and the Department of Science & Technology and the National Research Foundation for financing the NIKON micro-focus X-ray tomography system. For help with R scripts, we would like to thank Henning Winker. This project was funded by research grants to DSJ from the South African Research Chair Initiative of the Department of Science and Technology and administered by the National Research Foundation of South Africa (GUN 64798) and the University Research Committee of the University of Cape Town.