1. Center for Functional Anatomy and Evolution, The Johns Hopkins University School of Medicine , Baltimore, Maryland 21205, U.S.A.
2. Division of Fossil Primates, Duke University Lemur Center , Durham, North Carolina 27705, U.S.A.,
3. Department of Paleobiology, National Museum of Natural History, Smithsonian Institution , Washington, District of Columbia 20560, U.S.A.,