1. Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 45 Carleton St., Cambridge, MA 02142, USA
2. School of Earth Sciences, University College Dublin, Dublin 4, Ireland
3. Department of Ornithology, Senckenberg Research Institute and Natural History Museum, Senckenberganlage 25, 60325 Frankfurt, Germany
4. School of Biological Sciences, University of Bristol, Life Sciences Building, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
5. School of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol BS8 1RJ, UK