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Canidae (pronounced /ˈkænɨdiː/[2]) is the biological family of carnivorous and omnivorous mammals that includes the wolves, foxes, jackals, coyotes, and the domestic dog; a member of this family is called a canid (/ˈkeɪnɨd/). The Canidae family is divided into the "wolf-like" and "dog-like" animals of the tribe Canini and the "foxes" of the tribe Vulpini. The two species of the basal Caninae are more primitive and do not fit into either tribe.
[edit] Classification and relationshipThe 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).[3] 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.[1] 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 of the Canids -65 — – -60 — – -55 — – -50 — – -45 — – -40 — – -35 — – -30 — – -25 — – -20 — – -15 — – -10 — – -5 — – 0 — ← K-T mass extinction ← First Hesperocyoninae ← First Borophaginae ← ← Modern-looking dogs[verification needed] ← Canine radiation [edit] Evolution[edit] Eocene epochCarnivorans evolved from miacoids about 55 million years ago during the late Paleocene.[4] 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.[5] The Canidae family soon subdivided into three subfamilies, each of which diverged during the Eocene: Hesperocyoninae (~39.74-15 Mya), Borophaginae (~36-2 Mya), and the Caninae 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.[6]:Fig. 1 Only the Caninae lineage, commonly referred to as "canines," survived to the present day. [edit] Oligocene epochThe earliest 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 became extinct except for the Nothocyon and Leptocyon branches. These branches led to the borophagine and canine radiations.[7] [edit] Miocene epochAround 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. [edit] Early PlioceneDuring 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.[8] 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. [edit] Middle PlioceneAround 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. [edit] Late PlioceneAt 0.3 Mya Canis lupus (the gray wolf) was fully developed and had spread throughout Europe and northern Asia. Berengia offered a way to North America.[9] 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 8000 years ago the dire wolf became extinct. [edit] CharacteristicsWild 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 24 cm long, to the Gray Wolf, which may be up to 2 m long, and can weigh up to 80 kg. With the exceptions of the Bush Dog and Raccoon Dog, 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 a dewclaw on the front feet; the only exception being the African Wild Dog(Lycaon pictus). 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. [10]  [edit] Social behaviorAlmost 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.[11] 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.[12] [edit] Dentition Most canids have 42 teeth, with a dental formula of: [edit] Canids and humans One canid, the domestic dog, 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. Most experts believe the domestic dog is descended from an Asian subspecies of the Gray Wolf. Among canids, only the gray wolf has been known to prey on humans.[13] There are at least two records of a coyotes killing humans,[14] and two of golden jackals killing children.[15] 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.[16] [edit] Species and taxonomy FAMILY CANIDAE [edit] Subfamily Caninae
 [edit] Fossil CanidaeClassification of Hesperocyoninae from Wang (1994)[17] and Borophaginae from Wang et al. (1999),[18] except where noted. [edit] Prehistoric Caninae[edit] Genus Canis
[edit] Genus Vulpini[edit] Basal Canids
[edit] First Caninae[edit] BorophaginaeBorophaginae : † (Ma = million years ago) (million years = in existence)
[edit] HesperocyoninaeHesperocyoninae : † (Ma = million years ago)
[edit] See also
[edit] References
[edit] General referencesXiaoming 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 [edit] External links
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