His research is focused on the systematics and morphometrics of late Mesozoic and Cenozoic bryozoans found in deposits located in the Caribbean, especially the Dominican Republic, Panama, Costa Rica, and Venezuela, and the Gulf coast of the United States, particularly Florida, Alabama, and Mississippi.
During his tenure at Columbia he trained a number of students who later became prominent paleontologists, including Stephen Jay Gould, Niles Eldredge, Steven M. Stanley, Alan Cheetham, Alfred Fischer, and Don Boyd.
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