He was previously head curator of herpetology at the American Museum of Natural History, as well as president of both the Society for the Study of Amphibians and Reptiles (1998) and the American Society of Ichthyologists and Herpetologists (2006).
Korábban az Amerikai Természetrajzi Múzeum (American Museum of Natural History) kurátora volt, emellett igazgatója volt a Society for the Study of Amphibians and Reptiles társaságnak (1998) és az American Society of Ichthyologists and Herpetologists társaságnak (2006).