Urocyon (from the Greek word for "tailed dog"[5]) is a genus of Canidae which includes the gray fox (Urocyon cinereoargenteus) and the island fox (Urocyon littoralis).[1] These two fox species are found in the Western Hemisphere. Whole genome sequencing indicates that Urocyon is the most basal genus of the living canids.[6] Fossils of what is believed to be the ancestor of the gray fox, Urocyon progressus, have been found in Kansas and date to the Upper Pliocene,[7] with some undescribed specimens dating even older.[8]