1. Integrative Research Center, Field Museum of Natural History, 1400 South Lake Shore Drive, Chicago, Illinois 60605, U.S.A.,
2. Burke Museum and Department of Biology, University of Washington, Seattle, Washington 98195, U.S.A.,
3. Evolutionary Studies Institute, School for Geosciences, University of the Witwatersrand, Johannesburg, Private Bag 3 Wits 2050, South Africa,
4. Karoo Palaeontology, Iziko South African Museum, P.O. Box 61, Cape Town 8000, South Africa