Canidae (/ˈkænɪdiː/;[3] from Latin, canis, "dog") is a biological family of dog-like carnivorans, colloquially referred to as dogs, and constitutes a clade. A member of this family is also called a canid (/ˈkeɪnɪd/).[4] There are three subfamilies found within the canid family, which are the extinct Borophaginae and Hesperocyoninae, and the extant Caninae.[5] The Caninae are known as canines,[6] and include domestic dogs, wolves, foxes, coyotes and other extant and extinct species.
Canids are found on all continents except Antarctica, having arrived independently or accompanied human beings over extended periods of time. Canids vary in size from the 2-metre-long (6.6 ft) gray wolf to the 24-centimetre-long (9.4 in) fennec fox. The body forms of canids are similar, typically having long muzzles, upright ears, teeth adapted for cracking bones and slicing flesh, long legs, and bushy tails. They are mostly social animals, living together in family units or small groups and behaving cooperatively. Typically, only the dominant pair in a group breeds, and a litter of young are reared annually in an underground den. Canids communicate by scent signals and vocalizations. One canid, the domestic dog, originated from a symbiotic relationship with Upper Paleolithic humans and today remains one of the most widely kept domestic animals.
In the history of the carnivores, the family Canidae is represented by the two extinct subfamilies designated as Hesperocyoninae and Borophaginae, and the extant subfamily Caninae.[5] This subfamily includes all living canids and their most recent fossil relatives.[1] All living canids as a group form a dental monophyletic relationship with the extinct borophagines, with both groups having a bicuspid (two points) on the lower carnassial talonid, which gives this tooth an additional ability in mastication. This, together with the development of a distinct entoconid cusp and the broadening of the talonid of the first lower molar, and the corresponding enlargement of the talon of the upper first molar and reduction of its parastyle distinguish these late Cenozoic canids and are the essential differences that identify their clade.[1]: p6
The cat-like feliformia and dog-like caniforms emerged within the Carnivoramorpha around 45–42 Mya (million years ago).[7] The Canidae first appeared in North America during the Late Eocene (37.8-33.9 Ma). They did not reach Eurasia until the Miocene or to South America until the Late Pliocene.[1]: 7
This cladogram shows the phylogenetic position of canids within Caniformia, based on fossil finds:[1]
The Canidae today includes a diverse group of some 34 species ranging in size from the maned wolf with its long limbs to the short-legged bush dog. Modern canids inhabit forests, tundra, savannahs, and deserts throughout tropical and temperate parts of the world. The evolutionary relationships between the species have been studied in the past using morphological approaches, but more recently, molecular studies have enabled the investigation of phylogenetics relationships. In some species, genetic divergence has been suppressed by the high level of gene flow between different populations and where the species have hybridized, large hybrid zones exist.[8]