James Allen Hopson (born 1935) is an American paleontologist and professor (now retired) at the University of Chicago. His work has focused on the evolution of the synapsids (a group of amniotes that includes the mammals), and has been focused on the transition from basal synapsids to mammals, from the late Paleozoic through the Mesozoic Eras. He received his doctorate at Chicago in 1965, and worked at Yale before returning to Chicago in 1967 as a faculty member in Anatomy, and has also been a research associate at the Field Museum of Natural History since 1971.[1] He has also worked on the paleobiology of dinosaurs, and his work, along with that of Peter Dodson, has become a foundation piece for the modern understanding of duckbill crests, social behavior, and variation.[2]