Curator, research scientist Field Museum, Chicago, since 1983, senior vice president, head, collections and research, since 2004. Research associate American Museum Natural History, New York City, since 1984. Adjunct lecturer University Chicago, since 1986.
Adjunct professor University Illinois, since 1993. Editor Journal Vertebrate Paleontology, 2003—2006. Editorial board member Zoological Journal Linnean Society, London, 2006—2007.
Board and founding member Chicago Council of Scientific and Technology, since 2007, chairman, programming committee, since 2007. With Reserve Medical Corps United States Army, 1970-1975, Minneapolis.