1 CENIEH (National Research Center on Human Evolution), Paseo Sierra de Atapuerca 3, 09002 Burgos, Spain; Anthropology Department, University College London, 14 Taviton street, London WC1H 0BW, UK. Electronic address: maria.martinon@cenieh.es.
2 IIIPC (Instituto Internacional de Investigaciones Prehistóricas de Cantabria), Universidad de Cantabria, Avenida de los Castros 52, 39005 Santander, Spain.
3 Palaeo-Research Institute, University of Johannesburg, House 10, Bunting Road Campus, Auckland Park, Gauteng 2092, South Africa; Palaeoscience, Dept. of Archaeology and History, La Trobe University, Melbourne Campus, Corner of Plenty Road and Kingsbury Drive, Bundoora, 3086 VIC, Australia.
4 Human Origins Program, Smithsonian Institution, Washington, D.C., 20560, USA; School of Social Science, University of Queensland, St Lucia, Brisbane, Australia; Australian Research Centre for Human Evolution, Griffith University, Nathan, 4111, Brisbane, Australia.