Erratum: A proboscidean from the late Oligocene of Eritrea, a 'missing link' between early Elephantiformes and Elephantimorpha, and biogeographic implications (Proceedings of the National Academy of Sciences of the United States of America (November 14, 2006) 103, 46 (17206-17301) DOI:10.1073/pnas. 0603689103)