Protocyon was a hypercarnivore, suggested by its dental adaptations. Like many other large canids, it was most likely a pack hunter. It hunted the medium-sized grazers and browsers, and bite marks on fossils suggest that it may have hunted Glyptotherium. The find of a molar tooth found in Santa Vitória do Palmar in Brazil suggests a weight of between 25 to 37 kilograms for this particular specimen. Protocyon was named by Giebel in 1855 and assigned to Canidae by Carroll in 1988. A member of the Cerdocyonina lineage, its closest living relative might be the bush dog.