1 Department of Earth Sciences 'Ardito Desio', University of Milan, via Mangiagalli 34, I-20133 Milan, Italy; ALP - Alpine Laboratory of Paleomagnetism, via Luigi Massa 6, I-12016 Peveragno, CN, Italy. Electronic address: giovanni.muttoni1@unimi.it.
2 Department of Earth and Planetary Sciences, Rutgers University, Piscataway, NJ 08854, USA; Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964, USA.
3 Instituto de Geociências e Ciências Exatas, Universidade Estadual Paulista, Rio Claro, SP 13506-900, Brazil.
4 Department of Biological Sciences, Murray State University, Murray, KY 42071, USA.