Bashford Dean had an illustrious and curious dual career. As a young man, he assisted J. S. Newberry with studies of Devonian fishes, particularly giant armored placoderms and primitive sharks from Ohio. At the same time, Dean's interests in arms and armor led him to accumulate a magnificent collection that was eventually acquired by the Metropolitan Museum of Art. Dean published profusely on the evolution of fishes and on medieval armor, and was widely considered an authority in both subjects. He was associated with both the American Museum of Natural History and the Metropolitan Museum of Art from 1903 until his death, and at times he served as a curator in both institutions.