Prozostrodon was an advanced cynodont that was closely related to the ancestors of mammals. The remains were found in Brazil and are dated to the middle Triassic. It was originally described as a species of Thrinaxodon and was probably fairly similar to that genus in overall build. The sole find has a skull length of 6.7 cm, indicating the whole animal may have been the size of a cat, though there is some doubt as to whether the find represents an adult individual.