''Urocyon'' (Greek: "tailed dog") is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of Canidae which includes the

gray fox The gray fox (''Urocyon cinereoargenteus''), or grey fox, is an omnivorous mammal of the family Canidae, widespread throughout North America and Central America. This species and its only congener, the diminutive island fox (''Urocyon littor ...

(''Urocyon cinereoargenteus'') and the

island fox The island fox (''Urocyon littoralis'') is a small fox that is endemic to six of the eight Channel Islands of California. There are six subspecies, each unique to the island it lives on, reflecting its evolutionary history. They are generally d ...

(''Urocyon littoralis''). These two fox species are found in the Western Hemisphere.

Whole genome sequencing Whole genome sequencing (WGS), also known as full genome sequencing, complete genome sequencing, or entire genome sequencing, is the process of determining the entirety, or nearly the entirety, of the DNA sequence of an organism's genome at a ...

indicates that ''Urocyon'' is the most basal genus of the living canids. Fossils of what is believed to be the ancestor of the gray fox, ''

Urocyon progressus ''Urocyon'' (Greek: "tailed dog") is a genus of Canidae which includes the gray fox (''Urocyon cinereoargenteus'') and the island fox (''Urocyon littoralis''). These two fox species are found in the Western Hemisphere. Whole genome sequencing i ...

'', have been found in Kansas and date to the Upper

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Cozumel Cozumel (; yua, Kùutsmil) is an island and municipality in the Caribbean Sea off the eastern coast of Mexico's Yucatán Peninsula, opposite Playa del Carmen. It is separated from the mainland by the Cozumel Channel and is close to the Yucat� ...

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

. The last reported sighting was in 2001, but surveys focusing on this species have not yet been carried out. The Cozumel fox has not been scientifically described, but is a

dwarf Dwarf or dwarves may refer to: Common uses *Dwarf (folklore), a being from Germanic mythology and folklore * Dwarf, a person or animal with dwarfism Arts, entertainment, and media Fictional entities * Dwarf (''Dungeons & Dragons''), a humanoid ...

form as is the island fox, but slightly larger being up to three-quarters the size of the gray fox. No skins or complete skulls of the Cozumel fox exist in any museum exhibitions, so scientists have mainly examined sub-fossils collected during archaeological excavations of Mayan civilizations who inhabited the island about 1,500–500 years ago. Upon evaluating bones from about 12 adult individuals, scientists have concluded that the Cozumel fox is extremely small – approximately 60-80% the body size of other mainland specimens. The fox had been isolated on the Island of Cozumel for at least 5,000 years, and probably far longer. This would indicate that ''Urocyon'' had colonized the island before the first arrival of humans there.

Extinct species

References

Foxes Mammal genera Taxa named by Spencer Fullerton Baird {{canid-stub