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 (related to wolves) and Vulpini (related to foxes). The two species of the basal Caninae are more primitive and do not fit into either tribe.

Classification and relationship

The subdivision of Canidae into "foxes" and "true dogs" may not be in accordance with the actual relations; also the taxonomic classification of several canines is disputed. Recent DNA analysis shows that Canini (dogs) and Vulpini (foxes) are valid clades. (See phylogeny below). Molecular data implies a North American origin of living Canidae and an African origin of wolf-like canines (''Canis'', ''Cuon'', and ''Lycaon'').

Currently, the domestic dog is listed as a subspecies of ''Canis lupus'', ''C. l. familiaris'', and the dingo (also considered a domestic dog) as ''C. l. dingo'', provisionally a separate subspecies from ''C. l. familiaris''; the red wolf, eastern Canadian wolf, and Indian wolf are recognized as subspecies. Many sources list the domestic dog as ''Canis familiaris'', but others, including the Smithsonian Institution and the American Society of Mammalogists, more precisely list it as a subspecies of ''C. l. familiaris''; the red wolf, eastern Canadian wolf, and Indian wolf may or may not be separate species; the dingo has been in the past variously classified as ''Canis dingo'', ''Canis familiaris dingo'' and ''Canis lupus familiaris dingo''.

Evolution

Eocene epoch

Carnivorans evolved from miacoids about 55 million years ago during the late Paleocene. Then, about 50 million years ago, the carnivorans split into two main divisions: caniforms (dog-like) and feliforms (cat-like). By 40 million years ago the first clearly identifiable member of the dog family Canidae had arisen. It was called ''Prohesperocyon wilsoni'' and was found in what is now southwestern Texas. This fossil species bears a combination of features that definitively mark it as a canid: teeth that include the loss of the upper third molar (a general trend toward a more shearing bite), and the characteristically enlarged bony bulla (the rounded covering over the middle ear). Based on what we know about its descendants, ''Prohesperocyon'' likely had slightly more elongated limbs than its predecessors, along with toes that were parallel and closely touching, rather than splayed, as in bears.

The Canidae family soon subdivided into three subfamilies, each of which diverged during the Eocene: Hesperocyoninae (~39.74-15 Mya), Borophaginae (~34-2 Mya), and the Caninae (~34-0 Mya) lineage that led to present-day canids (wolves, foxes, coyotes, jackals, and domestic dogs). Each of these groups showed an increase in body mass with time, and sometimes exhibited a specialised hypercarnivorous diet that made them prone to extinction. Only the Caninae lineage, commonly referred to as "canines", survived to the present day.

Oligocene epoch

By the Oligocene, all three subfamilies of canids (Hesperocyoninae, Borophaginae, and Caninae) had appeared in the fossil records of North America. The earliest and most primitive branch of the Canidae was the Hesperocyoninae lineage, which included the coyote-sized ''Mesocyon'' of the Oligocene (38-24 Mya). These early canids probably evolved for fast pursuit of prey in a grassland habitat, and resembled modern civets in appearance. Hesperocyonines eventually became extinct in the middle Miocene. One of the early member of the Hesperocyonines, the genus ''Hesperocyon'', gave rise to ''Archaeocyon'' and ''Leptocyon''. These branches led to the borophagine and canine radiations.

Miocene epoch

Around 9-10 Mya during the Late Miocene, ''Canis'', ''Urocyon'', and ''Vulpes'' genera expanded from southwestern North America. This was the point where the canine radiation began. The success of these canines was related to the development of lower carnassials that were capable of both mastication and shearing. Around 8 Mya, Beringia offered the canines a way to enter Eurasia.

Pliocene epoch

During the Pliocene around (4-5 Mya) ''Canis lepophagus'' appeared in North America. This was small and sometimes coyote-like. Others were wolf-like in characteristics. It is theorized that ''Canis latrans'' (the coyote) descended from ''Canis lepophagus''.

The formation of the Isthmus of Panama about 3 Mya joined South America to North America, allowing canids to invade the former, where they diversified.

Pleistocene epoch

Around 1.5 to 1.8 Mya, a variety of wolves were present in Europe. Also, the North American wolf line appeared with ''Canis edwardii'', clearly identifiable as a wolf. ''Canis rufus'' appeared, possibly a direct descendent of ''Canis edwardii''. Around 0.8 Mya, ''Canis ambrusteri'' emerged in North America. A large wolf, it was found all over the continent. It is thought that this species migrated to South America where it became the ancestor of ''Canis dirus'', the dire wolf.

At 0.3 Mya ''Canis lupus'' (the gray wolf) was fully developed and had spread throughout Europe and northern Asia. Beringia offered a way to North America. At around 100,000 years ago, the dire wolf, one of the largest members of the dog family, had spread from South America to southern Canada and from coast to coast. The dire wolf shared its habitat with the gray wolf. Around 8,000 years ago the dire wolf became extinct.

Characteristics

Wild canids are found on every continent except Antarctica, and inhabit a wide range of different habitats, including deserts, mountains, forests, and grassland. They vary in size from the fennec fox at long, to the gray wolf, which may be up to long, and can weigh up to .

With the exceptions of the bush dog, raccoon dog and some domestic breeds, canids have relatively long legs and lithe bodies, adapted for chasing prey. All canids are digitigrade, meaning that they walk on their toes. They possess bushy tails, non-retractile claws, and, excepting the African wild dog (''Lycaon pictus''), a dewclaw on the front feet. They possess a baculum, which together with a cavernous body helps to create a copulatory tie during mating, locking the animals together for up to an hour. Young canids are born blind, with their eyes opening a few weeks after birth. [[File:Canis lupus pack surrounding Bison.jpg|thumb|Gray wolf pack hunting an American bison in Yellowstone National Park. Only a few species are arboreal - the North American gray fox, the closely related Channel Island fox, and the raccoon dog habitually climb trees.

Social behavior

Almost all canids are social animals and live together in groups. In most foxes and in many of the true dogs, a male and female pair work together to hunt and to raise their young. Gray wolves and some of the other larger canids live in larger groups called packs. African wild dogs have the largest packs, which can number as many as 90 animals. Some species form packs or live in small family groups depending on the circumstances, including the type of available food. In most species, there are also some individuals who live on their own. Within a canid pack, there is a system of dominance so that the strongest, most experienced animals lead the pack. In most cases, the dominant male and female are the only pack members to breed.

Canids communicate with each other by scent signals, by visual clues and gestures, and by vocalizations such as growls, barks, and howls. In most cases, groups have a home territory from which they drive out others. The territory is marked by leaving urine scent marks, which warn trespassing individuals.

Most canids bear young once a year, from 1 to 16 or more (in the case of the African wild dog) at a time. The young are born small and helpless and require a long period of care. They are kept in a den, most often dug into the ground, for warmth and protection. When they begin eating solid food, both parents, and often other pack members, bring food back for them from the hunt. This is most often vomited up from the adult's stomach. Young canids may take a year to mature and learn the skills they need to survive.

Dentition

thumb|right|Italian wolf skull Most canids have 42 teeth, with a dental formula of: . As in other members of Carnivora, the upper fourth premolar and lower first molar are adapted as carnassial teeth for slicing flesh. The molar teeth are strong in most species, allowing the animals to crack open bone to reach the marrow. The deciduous or baby teeth formula in canids is 3 1 3; molars are completely absent.

Species and taxonomy

FAMILY CANIDAE

Subfamily Caninae

True dogs - Tribe Canini

* ''Genus Canis''

** Gray wolf, ''Canis lupus'' (2.723 Ma to present)

*** Domestic dog, ''Canis lupus familiaris''

*** Dingo, most often classified as ''Canis lupus dingo'' (sometimes considered a separate taxon)

*** many other subspecies

** Coyote, ''Canis latrans'' (also called Prairie Wolf)

** 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'' or ''Canis 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 Cerdocyon''

** Crab-eating fox, ''Cerdocyon thous''

* ''Genus Dusicyon'' †

** Falklands wolf, ''Dusicyon australis'' †

* ''Genus Lycalopex (Pseudalopex)''

** Culpeo, ''Lycalopex culpaeus''

** Darwin's fox, ''Lycalopex fulvipes''

** South American gray fox, ''Lycalopex griseus''

** Pampas fox, ''Lycalopex gymnocercus''

** Sechura fox, ''Lycalopex sechurae''

** Hoary fox, ''Lycalopex vetulus''

* ''Genus Chrysocyon''

** Maned wolf, ''Chrysocyon brachyurus''

* ''Genus Speothos''

** Bush dog, ''Speothos venaticus''

True foxes - Tribe Vulpini

* ''Genus Vulpes''

** Arctic fox, ''Vulpes lagopus''

** Red fox, ''Vulpes vulpes'' (1 Ma to present)

** Swift fox, ''Vulpes velox''

** Kit fox, ''Vulpes macrotis''

** Corsac fox, ''Vulpes corsac''

** Cape fox, ''Vulpes chama''

** Pale fox, ''Vulpes pallida''

** Bengal fox, ''Vulpes bengalensis''

** Tibetan sand fox, ''Vulpes ferrilata''

** Blanford's fox, ''Vulpes cana''

** Rüppell's fox, ''Vulpes rueppelli''

** Fennec fox, ''Vulpes zerda''

* ''Genus Urocyon'' (2 Ma to present)

** Gray fox, ''Urocyon cinereoargenteus''

** Island fox, ''Urocyon littoralis''

** Cozumel fox, ''Urocyon sp.''

Basal Caninae

* ''Genus Otocyon'' (probably a vulpine close to ''Urocyon'')

** Bat-eared fox, ''Otocyon megalotis''

* ''Genus Nyctereutes''

** Raccoon dog, ''Nyctereutes procyonoides''

Prehistoric Canidae

Classification of Hesperocyoninae from Wang (1994) and Borophaginae from Wang, Tedford, Taylor (1999), and Caninae from Tedford, Wang, Taylor (2009) except where noted.

Caninae

Tribe Canini

* ''Genus Canis''

** ''Canis adoxus'' †

** ''Canis ameghinoi'' †

*''Canis apolloniensis'' () †

*''Canis armbrusteri'' () †

** ''Canis arnensis'' (3.4 Ma, †)

** ''Canis cautleyi '' †

* ''Canis cedazoensis'' () †

* ''Canis dirus'' (Dire wolf), () †

** ''Canis donnezani'' (4.0-3.1 Ma †, probably ancestor of wolves)

* ''Canis edwardii'' () †, first species of wolf in North America)

** ''Canis (Eucyon) cipio'' (8.2 Ma †, probably first species of ''Canis'' genus)

** ''Canis etruscus'' (3.4 Ma †)

* ''Canis ferox'' () †

** ''Canis gezi'' †

* ''Canis lepophagus'' ()†

** ''Canis michauxi '' †

** ''Canis mosbachensis'' (0.787 Ma †)

** ''Canis nehringi'' †

* ''Genus Cynotherium'' †

** Sardinian dhole, ''Cynotherium sardous'' †

''Genus Theriodictis'' ()†

** ''Theriodictis platensis'' (1.8 Ma †)

** ''Theriodictis tarijensis'' (1.8 Ma †)

** ''Theriodictis (Canis) proplatensis'' (2.1 Ma † )

* ''Genus Protocyon'' †

** ''Protocyon orcesi'' †

** ''Protocyon scagliarum'' †

** ''Protocyon troglodytes'' †

* ''Genus Dusicyon'' †

** ''Dusicyon avus'' †

* ''Genus Cerdocyon''

** ''Cerdocyon avius'' †

** ''Cerdocyon ensenadensis'' †

* ''Genus Speothos''

** ''Speothos pacivorus'' †

* ''Genus Nurocyon'' †

** ''Nurocyon chonokhariensis'' †

* ''Genus Xenocyon'' †

** ''Xenocyon falconeri'' (2.6 Ma †)

* ''Xenocyon lycaonoides'' () †

Tribe Vulpini

* ''Genus Vulpes'' (7 Ma to present)

** ''Vulpes alopecoides'' (2.6 Ma †)

** ''Vulpes cf. alopecoides'' (2.6 Ma †)

** ''Vulpes cf. vulpes'' (0.1275 Ma †)

** ''Vulpes galaticus'' (4.2 Ma †)

** ''Vulpes riffautae'' (7 Ma †)

Basal Caninae

* ''Genus Nyctereutes'' (7.1 Ma to present)

** ''Nyctereutes cf. donnezani'' (7.1 Ma †)

** ''Nyctereutes cf. megamastoides'' (3.158 Ma †)

** ''Nyctereutes donnezani'' (3.4 Ma †)

** ''Nyctereutes megamostoides'' (2.6 Ma †)

** ''Nyctereutes sinensis'' (3.4 Ma †)

First Caninae

* ''Genus Eucyon'' (8 Ma †)

** ''Eucyon davisi'' (8.3 Ma †, probably ancestor of ''Canis'')

** ''Eucyon minor'' (8 Ma †)

** ''Eucyon zhoui'' (8 Ma †)

** ''Eucyon monticinensis''(8 Ma †)

** ''Eucyon odessanus'' †

* ''Genus Leptocyon'' (24-16 Ma †)

** ''Leptocyon vafer'' (16 Ma †)

** ''Leptocyon vulpinus'' (24 Ma †)

Borophaginae

† (Ma = million years ago) (million years = in existence)

''Genus Archaeocyon'' () †

* ''Archaeocyon falkenbachi'' () †

* ''Archaeocyon leptodus'' () †

* ''Archaeocyon pavidus'' () †

''Genus Otarocyon'' () †

* ''Otarocyon cooki'' () †

* ''Otarocyon macdonaldi'' () †

''Genus Oxetocyon'' () †

* ''Oxetocyon cuspidatus'' () †

* ''Genus Rhizocyon'' (30 Ma)

** ''Rhizocyon oregonensis'' (30 Ma)

Tribe Phlaocyonini () †

''Genus Cynarctoides'' () †

* ''Cynarctoides acridens'' () †

* ''Cynarctoides emryi'' () †

* ''Cynarctoides gawnae'' () †

* ''Cynarctoides harlowi'' () †

** ''Cynarctoides lemur'' (30 Ma) †

* ''Cynarctoides luskensis'' () †

* ''Cynarctoides roii'' () †

* ''Genus Phlaocyon'' (30-19 Ma)

** ''Phlaocyon achoros''

** ''Phlaocyon annectens'' (22 Ma)

** ''Phlaocyon latidens'' (30 Ma)

** ''Phlaocyon leucosteus'' (22 Ma)

** ''Phlaocyon mariae''

** ''Phlaocyon marslandensis'' (19 Ma)

** ''Phlaocyon minor'' (30 Ma)

** ''Phlaocyon multicuspus''

* ''Phlaocyon taylori''

** ''Phlaocyon yakolai'' (19 Ma)

Tribe Borophagini () †

''Genus Cormocyon'' () †

* ''Cormocyon copei'' () †

* ''Cormocyon haydeni'' () †

''Genus Desmocyon'' () †

* ''Desmocyon matthewi'' () †

** ''Desmocyon thompsoni'' †

''Genus Metatomarctus'' () †

* ''Metatomarctus canavus'' () †

** ''Metatomarctus sp. A'' (16 Ma)

** ''Metatomarctus sp. B'' (16 Ma)

* ''Genus Eulopocyon'' (18-16 Ma)

** ''Eulopocyon brachygnathus'' (16 Ma)

** ''Eulopocyon spissidens'' (18 Ma)

* ''Genus Psalidocyon'' (16 Ma)

** ''Psalidocyon marianae'' (16 Ma)

''Genus Microtomarctus'' () †

* ''Microtomarctus conferta'' () †

* ''Genus Protomarctus'' (18 Ma)

** ''Protomarctus optatus'' (18 Ma)

* ''Genus Tephrocyon'' (16 Ma)

** ''Tephrocyon rurestris'' (16 Ma)

*Subtribe Cynarctina †

* ''Genus Paracynarctus'' () †

** ''Paracynarctus kelloggi'' () †

** ''Paracynarctus sinclairi'' () †

* ''Genus Cynarctus'' () †

** ''Cynarctus crucidens'' () †

** ''Cynarctus galushai'' () †

** ''Cynarctus marylandica'' () †

** ''Cynarctus saxatilis'' () †

** ''Cynarctus voorhiesi'' () †

Subtribe Aelurodontina () †

*''Genus Tomarctus'' () †

** ''Tomarctus brevirostris'' () †

** ''Tomarctus hippophaga'' () †

* ''Genus Aelurodon'' () †

** ''Aelurodon asthenostylus'' () †

** ''Aelurodon ferox'' () †

** ''Aelurodon mcgrewi'' () †

** ''Aelurodon montanensis'' () †

** ''Aelurodon stirtoni'' () †

** ''Aelurodon taxoides'' () †

Subtribe Borophagina () †

* ''Genus Paratomarctus'' () †

*** ''Paratomarctus euthos'' (13 Ma)

*** ''Paratomarctus temerarius'' (16 Ma)

* ''Genus Carpocyon'' () †

** ''Carpocyon compressus'' () †

** ''Carpocyon limosus'' () †

** ''Carpocyon robustus'' () †

** ''Carpocyon webbi'' () †

** ''Genus Protepicyon'' (16 Ma)

*** ''Protepicyon raki'' (16 Ma)

* ''Genus Epicyon'' () †

** ''Epicyon aelurodontoides'' () †

** ''Epicyon haydeni'' () †

** ''Epicyon saevus'' () †

* ''Genus Borophagus'' () †

*** ''Borophagus diversidens'' (5 Ma) †

** ''Borophagus dudleyi'' () †

** ''Borophagus hilli'' () †

** ''Borophagus littoralis'' () †

** ''Borophagus orc'' () †

** ''Borophagus parvus'' () †

** ''Borophagus pugnator'' () †

** ''Borophagus secundus'' () †

Hesperocyoninae

† (Ma = million years ago)

* ''Genus Cynodesmus'' (32-29 Ma)

** ''Cynodesmus martini'' (29 Ma)

** ''Cynodesmus thooides'' (32 Ma)

* ''?Genus Caedocyon''

** ''Caedocyon tedfordi''

* ''Genus Ectopocynus'' (32-19 Ma)

** ''Ectopocynus antiquus'' (32 Ma)

** ''Ectopocynus intermedius'' (29 Ma)

** ''Ectopocynus siplicidens'' (19 Ma)

* ''Genus Enhydrocyon'' (29-25 Ma)

** ''Enhydrocyon basilatus'' (25 Ma)

** ''Enhydrocyon crassidens'' (25 Ma)

** ''Enhydrocyon pahinsintewkpa'' (29 Ma)

** ''Enhydrocyon stenocephalus'' (29 Ma)

* ''Genus Hesperocyon'' (39.74-34 Ma)

** ''Hesperocyon coloradensis''

** ''Hesperocyon gregarius'' (37 Ma)

* ''Genus Mesocyon'' (34-29 Ma)

** ''Mesocyon brachyops'' (29 Ma)

** ''Mesocyon coryphaeus'' (29 Ma)

** ''Mesocyn temnodon''

* ''Genus Osbornodon'' (32-18 Ma)

** ''Osbornodon brachypus''

** ''Osbornodon fricki'' (18 Ma)

** ''Osbornodon iamonensis'' (21 Ma)

** ''Osbornodon renjiei'' (33 Ma)

* ''Osbornodon scitulus''

** ''Osbornodon sesnoni'' (32 Ma)

* ''Osbornodon wangi''

* ''Genus Paraenhydrocyon'' (30-25 Ma)

** ''Paraenhydrocyon josephi'' (30 Ma)

** ''Paraenhydrocyon robustus'' (25 Ma)

* ''Genus Philotrox'' (29 Ma)

** ''Philotrox condoni'' (29 Ma)

* ''Genus Prohesperocyon'' (36 Ma)

** ''Prohesperocyon wilsoni'' (36 Ma)

* ''Genus Sunkahetanka'' (29 Ma)

** ''Sunkahetanka geringensis'' (29 Ma)

Canids and humans

One canid, the domestic dog, a subspecies of the gray wolf, long ago entered into a partnership with humans and today remains one of the most widely kept domestic animals in the world and serves humanity in a great many important ways.

Among canids, only the gray wolf has been known to prey on humans. There are at least two records of coyotes killing humans, and two of golden jackals killing children. Some canid species have also been trapped and hunted for their fur and, especially the gray wolf and the red fox, for sport. Some canids are now endangered in the wild due to hunting, habitat loss, and the introduction of diseases from domestic dogs.

See also

Canine reproduction

==References==

General references

Xiaoming Wang, Richard H. Tedford, Mauricio Antón, ''Dogs: Their Fossil Relatives and Evolutionary History'', New York : Columbia University Press, 2008; ISBN 978-0-231-13528-3

External links

African Wild Dog Conservancy

Category:Mammal families

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