B.S., Geology, Michigan State University, 1962.
Ph.D., Paleozoology, University of Chicago, 1968.

Chair, Department of Geology, Field Museum of Natural History, 1981-1990.
Treasurer, Society of Vertebrate Paleontology, 1993-present.

Early diversification of tetrapods, particularly amphibians, of Mississippian, Pennsylvanian, and Early Permian age (ca. 360 to 270 million years before present) / systematics / comparative and functional morphology / biogeography.

Current studies are focused on: i) Relationships and morphology of primitive amphibians (as well as fish) from a Mississippian (ca. 335 million years before present) locality in southeastern Iowa. The locality has produced hundreds of specimens of the oldest tetrapods known from continental North America. ii) Continuing development of an interactive World Wide Web site for systematic data, which was implemented in 1995 with two colleagues, from the United States and the United Kingdom iii) Fossil evidence for the origin and early evolution of the tetrapod auditory system, and its implications for otic evolution as well as tetrapod relationships. iv) Origin and early evolution of the living amphibians (lissamphibians). I am interested in supervising student research on systematics, morphology, and biogeography of Paleozoic reptiles and amphibians.