1. School of Geography, Earth and Environmental Sciences; University of Birmingham; Edgbaston Birmingham B15 2TT UK
2. Department of Organismal Biology and Anatomy; University of Chicago; Chicago IL 60637-1508 USA
3. School of Dentistry; College of Medical and Dental Sciences; University of Birmingham; St Chad's Queensway Birmingham B4 6NN UK
4. Oxford University Museum of Natural History; Parks Road Oxford OX1 3PW UK