The genus Urocyon is a genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 that contains two (or possibly three) living Western Hemisphere foxes in the family Canidae

Canidae

Canidae is the biological family of carnivorous and omnivorous mammals that includes wolves, foxes, jackals, coyotes, and domestic dogs. A member of this family is called a canid . The Canidae family is divided into two tribes: Canini and Vulpini...

, the Gray Fox

Gray Fox

The gray fox is a mammal of the order Carnivora ranging throughout most of the southern half of North America from southern Canada to the northern part of South America...

 (Urocyon cinereoargenteus) and the closely related Island Fox

Island Fox

The island fox is a small fox that is native to six of the eight Channel Islands of California. There are six subspecies of the fox, each unique to the island it lives on, reflecting its evolutionary history...

 (Urocyon littoralis) which is a dwarf

Insular dwarfism

Insular dwarfism, a form of phyletic dwarfism, is the process and condition of the reduction in size of large animals – typically mammals – when their population's range is limited to a small environment, primarily islands. This natural process is distinct from the intentional creation of dwarf...

 cousin of the Gray Fox; as well as one fossil species, Urocyon progressus

Urocyon progressus

Urocyon progressus, also known as the Progressive Gray Fox, is an extinct carnivorous mammal of the genus Urocyon, and was most common in North America during the Blancan Stage on the geologic timescale. Fossil samples have been found in both Kansas and Texas. It may have been the ancestor of the...

.

Urocyon and the Raccoon Dog

Raccoon Dog

The raccoon dog , also known as the magnut or tanuki, is a canid indigenous to east Asia. It is the only extant species in the genus Nyctereutes...

 are the only canids able to climb trees. Urocyon is one of the oldest fox genera still in existence. A third species, apparently close to extinction or even already extinct, is (or was, until recently) found on the island of Cozumel

Cozumel

Cozumel is an island in the Caribbean Sea off the eastern coast of Mexico's Yucatan Peninsula, opposite Playa del Carmen, and close to the Yucatan Channel. Cozumel is one of the ten municipalities of the state of Quintana Roo...

, Mexico

Mexico

The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

. The Cozumel Fox

Cozumel Fox

The Cozumel Fox is an undescribed species of fox which is apparently close to extinction or even already extinct. It is found on the island of Cozumel, Mexico. The Cozumel Fox, which has not been scientifically described to date, is a dwarf form like the Island Fox but slightly larger, being up...

, which has not been scientifically described to date, is a dwarf form like the Island Fox but a bit larger, being up to three-quarters the size of the Gray Fox.