Canidae

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Canidae is the family of carnivorous and omnivorous mammals commonly known as canines. It includes dogs, wolves, foxes, coyotes, and jackals. These animals are all digitigrades, meaning they walk on their toes.

Classification

Note that the subdivision of Canidae into "foxes" and "true dogs" may not be in accordance with the actual relations, and that the taxonomic classification of several canines is disputed. Recent DNA analysis has shown, however, that Canini and Vulpini are valid clades, which exclude two genera: Nyctereutes and Otocyon. These are basal canids and are not closely related to either vulpines or canines. (Some evidence also suggests the same for Urocyon.)

Speothos and Chrysocyon are primitive members of Canini, but might be placed in their own clade. Cuon and Lycaon may in fact belong in Canis, and there is evidence that Alopex and Fennecus are not valid clades, but are both part of Vulpes.

The Domestic Dog is listed by some authorities as Canis familiaris and others (including the Smithsonian Institution and the American Society of Mammalogists) as a subspecies of the Gray Wolf (i.e., Canis lupus familiaris); the Red Wolf may or may not be a full species; and the Dingo is variously classified as Canis dingo, Canis lupus dingo, Canis familiaris dingo and Canis lupus familiaris dingo. At least one subspecies of wolf has recently been listed as a separate species - the Eastern Canadian Wolf, Canis lycaon. This is, however, still a controversial classification; the precise relationships among the Gray Wolf, Red Wolf, Eastern Canadian Wolf, and Coyote have yet to be worked out satisfactorily.

True dogs - Tribe Canini
* Genus Canis
** Coyote, Canis latrans (also called Prairie Wolf)
** Gray Wolf, Canis lupus
*** Domestic Dog, Canis lupus familiaris or Canis familiaris
*** Dingo, Canis dingo or Canis familiaris dingo or Canis lupus dingo.
*** many other proposed subspecies
** Red Wolf, Canis rufus or Canis lupus rufus
** Ethiopian Wolf, Canis simensis (also called Abyssinian Wolf, Simien Fox and Simien Jackal)
** Golden Jackal, Canis aureus
** Side-striped Jackal, Canis adustus
** Black-backed jackal, Canis mesomelas
* Genus Cuon
** Dhole, Cuon alpinus (also called Asian Wild Dog)
* Genus Lycaon
** African Wild Dog, Lycaon pictus (also called African Hunting Dog)
* Genus Atelocynus
** Short-eared Dog, Atelocynus microtis
* Genus Pseudalopex
** Culpeo, Pseudalopex culpaeus
** Darwin's Fox, Pseudalopex fulvipes
** Argentine Grey Fox, Pseudalopex griseus
** Pampas Fox, Pseudalopex gymnocercus
** Sechura Fox, Pseudalopex sechurae
** Hoary Fox, Pseudalopex vetulus
* Genus Cerdocyon
** Crab-eating Fox, Cerdocyon thous
* (Genus Dusicyon extinct)
** (Falkland Island Fox, Dusicyon australis extinct)
* Genus Speothos
** Bush Dog, Speothos venaticus
* Genus Chrysocyon
** Maned Wolf, Chrysocyon brachyurus
Foxes - Tribe Vulpini
* Genus Vulpes
** Red Fox, Vulpes vulpes
** Swift Fox, Vulpes velox
** Kit Fox, Vulpes macrotis
** Corsac Fox (or Steppe Fox), Vulpes corsac
** Cape Fox, Vulpes chama
** Pale Fox, Vulpes pallida
** Bengal Fox, Vulpes bengalensis
** Tibetan Fox, Vulpes ferrilata
** Blanford's Fox, Vulpes cana
** Rüppell's Fox, Vulpes rueppelli
** Fennec, Fennecus zerda
* Genus Alopex
** Arctic Fox, Alopex lagopus
* Genus Urocyon
** Gray Fox, Urocyon cinereoargenteus
** Island Fox, Urocyon littoralis
Basal canids
* Genus Nyctereutes
** Raccoon Dog, Nyctereutes procyonoides
* Genus Otocyon
** Bat-eared Fox, Otocyon megalotis

Dentition

Canines have 42 teeth - their dental formula is:

3.1.4.2

3.1.4.3

The deciduous or baby teeth formula is 3 1 3, where molars are completely absent.

Copulation

Further information: Non-human animal sexuality

When copulating, a male canine initially mounts the female from behind, as with most tetrapods, a position known informally as doggy style. The female will hold her tail to the side if receptive. The male will often move about as he tries to get a good purchase upon her, and whilst attempting penetration of his penis to the female's vulva. At this point, the penis is not erect, it is slender and held rigid by a small bone inside, known as the baculum, which canines (but not humans) have.

When the male achieves penetration, he will often hold tighter and thrust faster, and it is at this point when he is mating that his penis grows. Canine reproduction is different from human sexual intercourse, because human males become erect first, and then enter the female; canine males enter first, then swell and become erect.

The male dog has a bulbus glandis, a spherical area of erectile tissue at the base of the penis, which traps the penis inside the female's vagina during copulation as it becomes engorged with blood. [link]

Once the penis is locked into the vagina by the bulbus glandis, the male will usually lift a leg and swing it over the female's back while turning around. The two stand with their hind ends touching and the penis locked inside the vagina while ejaculation occurs, decreasing leakage of semen from the vagina. After some time, typically 5 - 20 minutes (but sometimes longer), the bulbus glandis disengorges, allowing the mates to separate. Virgin dogs can become quite distressed at finding themselves unable to separate during their first copulation, and may try to pull away or run.

Note that similar canine mounting behavior (sometimes with pelvic thrusting) is also used by dominant canines of both genders. Dominance mounting, with or without thrusting, should not be confused with copulatory mounting, in which the thrusting is short term until a "tie" is achieved.

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