1 Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), Burgos, Spain; Australian Nuclear Science and Technology Organisation (ANSTO), Sydney, Australia. Electronic address: toshiyuki.fujioka@cenieh.es.
2 Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), Burgos, Spain.
3 Facultat de Lletres, Universitat Autonoma de Barcelona, 08193 Bellaterra, Spain.
4 Department of Geosciences, University of Wisconsin-Milwaukee, 3209 N. Maryland Ave, Milwaukee, WI, 53217, USA.
5 Department of Earth and Atmospheric Sciences, Indiana University, 1001 E 10th Street, Bloomington, IN 47405, USA; The Stone Age Institute, 1392 W. Dittemore Rd, Bloomington, IN 47407, USA.
6 Instituto de Historia, CSIC-National Research Council, Albasanz 26-28, 28037 Madrid, Spain. Electronic address: ignacio.delatorre@csic.es.