1. School of Earth and Environmental Sciences, James Cook University, Townsville, QLD 4811, Australia.
2. School of Geosciences, University of the Witwatersrand, Johannesburg, Private Bag 3, Wits 2050, South Africa.
3. Institute for Human Evolution, University of the Witwatersrand, Johannesburg, Private Bag 3, Wits 2050, South Africa.
4. Department of Evolutionary Anthropology, Box 90383, Duke University, Durham, NC 27708, USA.
5. Institute of Geological Sciences, University of Bern, Baltzerstrasse 3, 3012 Bern, Switzerland.
6. Department of Geology, University of Johannesburg, Auckland Park 2006, South Africa.
7. School of Earth Sciences, University of Melbourne, VIC 3010, Australia.
8. Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA.
9. Department of Earth and Planetary Sciences, University of California, Santa Cruz, Santa Cruz, CA 95064, USA.
10. School of Geography, Politics and Sociology, Newcastle University, Claremont Road, Newcastle upon Tyne NE1 7RU, UK.
11. UNSW Archaeomagnetism Laboratory, School of Medical Sciences, University of New South Wales, Sydney, NSW 2052, Australia.
12. Geomagnetism Laboratory, Oliver Lodge, Department of Earth and Ocean Science, University of Liverpool, L69 3BX, UK.
13. Laboratoire Tectonique, Institut de Physique du Globe Paris, 4 Place Jussieu, 75252 Paris, France.