This research was supported by grants from the National Research Foundation (African Origins Program), The University of Cape Town University Research Council, The Vice-Chancellor's Fund at the University of Cape Town, the U.S. National Science Foundation (BCS 1219494 and BCS 1219455), and the Department of Earth and Planetary Sciences at Johns Hopkins University. Palaeomagnetic work was supported by Australian Research Council Future Fellowship grant FT120100399 to AIRH.