Morphology in biology is the study of the form and structure of organisms and their specific structural features.
82-730: Canidae ( / ˈ k æ n ɪ d iː / ; 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 ( / ˈ k eɪ n ɪ d / ). The family includes three subfamilies : the Caninae , and the extinct Borophaginae and Hesperocyoninae . The Caninae are known as canines, and include domestic dogs , wolves , coyotes , foxes , jackals and other species. Canids are found on all continents except Antarctica , having arrived independently or accompanied by human beings over extended periods of time. Canids vary in size from
164-520: A baculum and a structure called the bulbus glandis that expands during copulation , forming a copulatory tie that lasts for up to an hour. Young canids are born blind, with their eyes opening a few weeks after birth. All living canids (Caninae) have a ligament analogous to the nuchal ligament of ungulates used to maintain the posture of the head and neck with little active muscle exertion; this ligament allows them to conserve energy while running long distances following scent trails with their nose to
246-530: A dental formula of: 3.1.4.2 3.1.4.3 . The bush dog has only one upper molar with two below, the dhole has two above and two below. and the bat-eared fox has three or four upper molars and four lower ones. 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 3.1.3 , molars being completely absent. Almost all canids are social animals and live together in groups. In general, they are territorial or have
328-560: A gestation of 50 to 60 days, while larger species average 60 to 65 days. The time of year in which the breeding season occurs is related to the length of day, as has been shown for several species that have been moved across the equator and experiences a six-month shift of phase. Domestic dogs and certain small canids in captivity may come into oestrus more often, perhaps because the photoperiod stimulus breaks down under conditions of artificial lighting. Canids have an oestrus period of 1 to 20 days, lasting one week in most species. The size of
410-603: 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. The cat-like Feliformia and dog-like Caniformia emerged within the Carnivoramorpha around 45–42 Mya (million years ago). The Canidae first appeared in North America during
492-400: A diverse group of some 37 species ranging in size from the maned wolf with its long limbs to the short-legged bush dog. Modern canids inhabit forests, tundra, savannas, 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
574-457: A food resource when in heat. Outside of the breeding season their efforts were not as persistent or successful. This shows that the food-for-sex hypothesis likely plays a role in the food sharing among canids and acts as a direct benefit for the females. Another study on free-ranging dogs found that social factors played a significant role in the determination of mating pairs. The study, done in 2014, looked at social regulation of reproduction in
656-450: 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 is 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
738-485: A home range and sleep in the open, using their dens only for breeding and sometimes in bad weather. 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 packs which may consist of 20 to 40 animals and packs of fewer than about seven individuals may be incapable of successful reproduction. Hunting in packs has
820-432: A home territory from which they drive out other conspecifics . Canids use urine scent marks to mark their food caches or warn trespassing individuals. Social behavior is also mediated by secretions from glands on the upper surface of the tail near its root and from the anal glands , preputial glands , and supracaudal glands . Canids as a group exhibit several reproductive traits that are uncommon among mammals as
902-414: A large role in the determination of mating pairs in dogs. Canids also show a wide range of parental care and in 2018 a study showed that sexual conflict plays a role in the determination of intersexual parental investment . The studied looked at coyote mating pairs and found that paternal investment was increased to match or near match the maternal investment. The amount of parental care provided by
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#1732798167822984-419: A larger trigonid indicating a hypercarnivore and a larger talonid indicating a more omnivorous diet. Because of its low variability, the length of the lower carnassial is used to provide an estimate of a carnivore's body size. A study of the estimated bite force at the canine teeth of a large sample of living and fossil mammalian predators, when adjusted for their body mass, found that for placental mammals
1066-444: A litter varies, with from one to 16 or more pups being born. The young are born small, blind and helpless and require a long period of parental care. They are kept in a den, most often dug into the ground, for warmth and protection. When the young 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. Where such pack involvement in
1148-705: A longer duration for a reduced energy requirement. By doing this the mothers increasing the likelihood of their pups surviving infancy and reaching adulthood and thereby increase their own fitness. A study done in 2017 found that aggression between male and female gray wolves varied and changed with age. Males were more likely to chase away rival packs and lone individuals than females and became increasingly aggressive with age. Alternatively, females were found to be less aggressive and constant in their level of aggression throughout their life. This requires further research but suggests that intersexual aggression levels in gray wolves relates to their mating system . Tooth breakage
1230-459: A morphology more closely associated with canids from Eurasia instead of Africa. Morphology (biology) This includes aspects of the outward appearance (shape, structure, color, pattern, size), i.e. external morphology (or eidonomy ), as well as the form and structure of internal parts like bones and organs , i.e. internal morphology (or anatomy ). This is in contrast to physiology , which deals primarily with function. Morphology
1312-423: A scavenger than a hunter; its molars appear to be adapted for crushing bones and it may have gone extinct as a result of the extinction of the large herbivorous animals on whose carcasses it relied. In 2015, a study of mitochondrial genome sequences and whole-genome nuclear sequences of African and Eurasian canids indicated that extant wolf-like canids have colonized Africa from Eurasia at least five times throughout
1394-630: A separate species, Canis anthus ( African golden wolf ). According to a phylogeny derived from nuclear sequences, the Eurasian golden jackal ( Canis aureus ) diverged from the wolf/coyote lineage 1.9 Mya , but the African golden wolf separated 1.3 Mya. Mitochondrial genome sequences indicated the Ethiopian wolf diverged from the wolf/coyote lineage slightly prior to that. Wild canids are found on every continent except Antarctica, and inhabit
1476-529: A similar appearance as a result of convergent evolution or even mimicry . In addition, there can be morphological differences within a species, such as in Apoica flavissima where queens are significantly smaller than workers. A further problem with relying on morphological data is that what may appear morphologically to be two distinct species may in fact be shown by DNA analysis to be a single species. The significance of these differences can be examined through
1558-492: A whole. They are typically monogamous , provide paternal care to their offspring, have reproductive cycles with lengthy proestral and dioestral phases and have a copulatory tie during mating. They also retain adult offspring in the social group, suppressing the ability of these to breed while making use of the alloparental care they can provide to help raise the next generation. Most canid species are spontaneous ovulators, though maned wolves are induced ovulators . During
1640-402: A wide range of different habitats, including deserts , mountains , forests , and grasslands . They vary in size from the fennec fox, which may be as little as 24 cm (9.4 in) in length and weigh 0.6 kg (1.3 lb), to the gray wolf , which may be up to 160 cm (5.2 ft) long, and can weigh up to 79 kg (174 lb). Only a few species are arboreal —the gray fox ,
1722-583: A wolf, and Canis rufus appeared, possibly a direct descendant of C. edwardii . Around 0.8 Mya, Canis ambrusteri emerged in North America. A large wolf, it was found all over North and Central America and was eventually supplanted by the dire wolf, which then spread into South America during the Late Pleistocene. By 0.3 Mya, a number of subspecies of the gray wolf ( C. lupus ) had developed and had spread throughout Europe and northern Asia. The gray wolf colonized North America during
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#17327981678221804-592: A workshop hosted by the IUCN /SSC Canid Specialist Group recommends that because DNA evidence shows the side-striped jackal ( Canis adustus ) and black-backed jackal ( Canis mesomelas ) to form a monophyletic lineage that sits outside of the Canis / Cuon / Lycaon clade, that they should be placed in a distinct genus, Lupulella Hilzheimer, 1906 with the names Lupulella adusta and Lupulella mesomelas . The fossil record shows that feliforms and caniforms emerged within
1886-479: Is a branch of life science dealing with the study of the gross structure of an organism or taxon and its component parts. The etymology of the word "morphology" is from the Ancient Greek μορφή ( morphḗ ), meaning "form", and λόγος ( lógos ), meaning "word, study, research". While the concept of form in biology, opposed to function , dates back to Aristotle (see Aristotle's biology ),
1968-409: Is a frequent result of carnivores' feeding behaviour. Carnivores include both pack hunters and solitary hunters. The solitary hunter depends on a powerful bite at the canine teeth to subdue their prey, and thus exhibits a strong mandibular symphysis . In contrast, a pack hunter, which delivers many shallower bites, has a comparably weaker mandibular symphysis. Thus, researchers can use the strength of
2050-595: Is also higher when taking and consuming large prey. In comparison to extant gray wolves, the extinct Beringian wolves included many more individuals with moderately to heavily worn teeth and with a significantly greater number of broken teeth. The frequencies of fracture ranged from a minimum of 2% found in the Northern Rocky Mountain wolf (Canis lupus irremotus) up to a maximum of 11% found in Beringian wolves. The distribution of fractures across
2132-607: Is based on the DNA phylogeny of Lindblad-Toh et al . (2005), modified to incorporate recent findings on Canis species, Canis latrans (coyote) [REDACTED] Canis rufus (red wolf) [REDACTED] Canis lycaon (Algonquin wolf) [REDACTED] Canis lupus (gray wolf) [REDACTED] Canis familiaris (domestic dog) [REDACTED] Canis lupaster ( African golden wolf ) [REDACTED] Canis simensis ( Ethiopian wolf ) [REDACTED] Canis aureus ( golden jackal ) [REDACTED] In 2019,
2214-445: Is commonly referred to as the wolf event . It is associated with the formation of the mammoth steppe and continental glaciation. Canis spread to Europe in the forms of C. arnensis , C. etruscus , and C. falconeri . However, a 2021 genetic study of the dire wolf ( Aenocyon dirus ), previously considered a member of Canis , found that it represented the last member of an ancient lineage of canines originally indigenous to
2296-403: Is only used for cutting. They use their molars for grinding except for the lower first molar m1 (the lower carnassial) that has evolved for both cutting and grinding depending on the canid's dietary adaptation. On the lower carnassial, the trigonid is used for slicing and the talonid is used for grinding. The ratio between the trigonid and the talonid indicates a carnivore's dietary habits, with
2378-485: Is said to exemplify the two major deviations in biological thinking at the time – whether animal structure was due to function or evolution. Most taxa differ morphologically from other taxa. Typically, closely related taxa differ much less than more distantly related ones, but there are exceptions to this. Cryptic species are species which look very similar, or perhaps even outwardly identical, but are reproductively isolated. Conversely, sometimes unrelated taxa acquire
2460-399: Is used for slicing and the talonid is used for grinding. The ratio between the trigonid and the talonid indicates a carnivore's dietary habits, with a larger trigonid indicating a hypercarnivore and a larger talonid indicating a more omnivorous diet. Because of its low variability, the length of the lower carnassial is used to provide an estimate of a carnivore's body size. A study of
2542-555: The African wild dog . The gray wolf ranked between these two. The eating of bone increases the risk of accidental fracture due to the relatively high, unpredictable stresses that it creates. The most commonly broken teeth are the canines, followed by the premolars, carnassial molars, and incisors. Canines are the teeth most likely to break because of their shape and function, which subjects them to bending stresses that are unpredictable in direction and magnitude. The risk of tooth fracture
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2624-508: The Beringian land bridge allowed members of the genus Eucyon a means to enter Asia from North America and they continued on to colonize Europe. The Canis , Urocyon , and Vulpes genera developed from canids from North America , where the canine radiation began. The success of these canids was related to the development of lower carnassials that were capable of both mastication and shearing. Around 5 million years ago, some of
2706-663: The Ethiopian wolf ( C. simensis ), eastern wolf ( C. lycaon ), and the African golden wolf ( C. lupaster ) are four of the many Canis species referred to as "wolves". Species that are too small to attract the word "wolf" are called coyotes in the Americas and jackals elsewhere. Although these may not be more closely related to each other than they are to C. lupus , they are, as fellow Canis species, more closely related to wolves and domestic dogs than they are to foxes , maned wolves , or other canids which do not belong to
2788-832: The Late Eocene (37.8-33.9 Mya). They did not reach Eurasia until the Late Miocene or to South America until the Late Pliocene . This cladogram shows the phylogenetic position of canids within Caniformia , based on fossil finds: (bears, procyonids, pinnipeds, etc.) [REDACTED] (various † Miacis spp.) [REDACTED] ( Mesocyon , Enhydrocyon , Hesperocyon , and other basal canines, e.g. Cynodictis ) [REDACTED] ( Aelurodon , cynarctins , and others) [REDACTED] (all modern canids and extinct relatives) [REDACTED] The Canidae are
2870-576: The Middle Pleistocene and was limited in Eurasia to the small wolves of the Canis mosbachensis –Canis variabilis group and the large hypercarnivorous Canis (Xenocyon) lycaonoides . The hypercarnivore Xenocyon gave rise to the modern dhole and the African wild dog . Dentition relates to the arrangement of teeth in the mouth, with the dental notation for the upper-jaw teeth using
2952-540: The Pliocene and Pleistocene , which is consistent with fossil evidence suggesting that much of the African canid fauna diversity resulted from the immigration of Eurasian ancestors, likely coincident with Plio-Pleistocene climatic oscillations between arid and humid conditions. In 2017, the fossil remains of a new Canis species, named Canis othmanii , was discovered among remains found at Wadi Sarrat, Tunisia, from deposits that date 700,000 years ago. This canine shows
3034-659: The gray wolf and coyote , likely only arrived in the New World during the Late Pleistocene , where their dietary flexibility and/or ability to hybridize with other canids allowed them to survive the Quaternary extinction event , unlike the dire wolf. Xenocyon (strange wolf) is an extinct subgenus of Canis . The diversity of the Canis group decreased by the end of the Early Pleistocene to
3116-408: The mandible teeth . Teeth are numbered using one side of the mouth and from the front of the mouth to the back. In carnivores , the upper premolar P4 and the lower molar m1 form the carnassials that are used together in a scissor-like action to shear the muscle and tendon of prey. Canids use their premolars for cutting and crushing except for the upper fourth premolar P4 (the upper carnassial) that
3198-599: The maned wolf ( Chrysocyon brachyurus ), the short-eared dog ( Atelocynus microtis ), the bush dog ( Speothos venaticus ), the crab-eating fox ( Cerdocyon thous ), and the South American foxes ( Lycalopex spp.). The monophyly of this group has been established by molecular means. During the Pleistocene , the North American wolf line appeared, with Canis edwardii , clearly identifiable as
3280-405: 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 co-operatively. Typically, only the dominant pair in
3362-533: The African hunting dog (142), the gray wolf (136), the dhole (112), and the dingo (108). The bite force at the carnassials showed a similar trend to the canines. A predator's largest prey size is strongly influenced by its biomechanical limits. There is little variance among male and female canids. Canids tend to live as monogamous pairs. Wolves, dholes , coyotes , and jackals live in groups that include breeding pairs and their offspring. Wolves may live in extended family groups. To take prey larger than themselves,
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3444-404: The African wild dog, the dhole, and the gray wolf depend on their jaws as they cannot use their forelimbs to grapple with prey. They work together as a pack consisting of an alpha pair and their offspring from the current and previous years. Social mammal predators prey on herbivores with a body mass similar to that of the combined mass of the predator pack. The gray wolf specializes in preying on
3526-518: The ICZN's Direction 22 added Canis familiaris as the type species for genus Canis to the official list. Canis is primitive relative to Cuon , Lycaon , and Xenocyon in its relatively larger canines and lack of such dental adaptations for hypercarnivory as m1–m2 metaconid and entoconid small or absent; M1–M2 hypocone small; M1–M2 lingual cingulum weak; M2 and m2 small, may be single-rooted; m3 small or absent; and wide palate. The cladogram below
3608-557: The Late Miocene and Early Pliocene but they were not the top predators. For Canis populations in the New World, Eucyon in North America gave rise to early North American Canis which first appeared in the Miocene (6 million YBP) in south-western United States and Mexico. By 5 million YBP the larger Canis lepophagus , ancestor of wolves and coyotes, appeared in the same region. Around 5 million years ago, some of
3690-563: The New World that had diverged prior to the appearance of Canis , and that its lineage had been distinct since the Miocene with no evidence of introgression with Canis . The study hypothesized that the Neogene canids in the New World, Canis armbrusteri and Canis edwardii , were possibly members of the distinct dire wolf lineage that had convergently evolved a very similar appearance to members of Canis . True members of Canis , namely
3772-582: The Old World Eucyon evolved into the first members of Canis , In the Pliocene , around 4–5 Mya, Canis lepophagus appeared in North America. This was small and sometimes coyote-like. Others were wolf-like. C. latrans (the coyote) is theorized to descend from C. lepophagus . The formation of the Isthmus of Panama , about 3 Mya, joined South America to North America, allowing canids to invade South America , where they diversified. However,
3854-660: The Old World Eucyon evolved into the first members of Canis , and the position of the canids would change to become a dominant predator across the Palearctic . The wolf-sized C. chihliensis appeared in northern China in the Mid-Pliocene around 4-3 million YBP. This was followed by an explosion of Canis evolution across Eurasia in the Early Pleistocene around 1.8 million YBP in what
3936-506: The Pliocene and Pleistocene, which is consistent with fossil evidence suggesting that much of African canid fauna diversity resulted from the immigration of Eurasian ancestors, likely coincident with Plio-Pleistocene climatic oscillations between arid and humid conditions. When comparing the African and Eurasian golden jackals, the study concluded that the African specimens represented a distinct monophyletic lineage that should be recognized as
4018-596: The advantage that larger prey items can be tackled. Some species form packs or live in small family groups depending on the circumstances, including the type of available food. In most species, some individuals 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
4100-470: The bite force at the canines was greatest in the extinct dire wolf (163), followed among the modern canids by the four hypercarnivores that often prey on animals larger than themselves: the African wild dog (142), the gray wolf (136), the dhole (112), and the dingo (108). The bite force at the carnassials showed a similar trend to the canines. A predator's largest prey size is strongly influenced by its biomechanical limits. Most canids have 42 teeth , with
4182-646: The clade Carnivoramorpha 43 million YBP . The caniforms included the fox-like genus Leptocyon , whose various species existed from 24 million YBP before branching 11.9 million YBP into Vulpes (foxes) and Canini (canines). The jackal-sized Eucyon existed in North America from 10 million YBP and by the Early Pliocene about 6-5 million YBP the coyote-like Eucyon davisi invaded Eurasia. The canids that had emigrated from North America to Eurasia – Eucyon , Vulpes , and Nyctereutes – were small to medium-sized predators during
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#17327981678224264-434: The closely related island fox and the raccoon dog habitually climb trees. All canids have a similar basic form, as exemplified by the gray wolf, although the relative length of muzzle, limbs, ears, and tail vary considerably between species. With the exceptions of the bush dog, the raccoon dog and some domestic dog breeds , canids have relatively long legs and lithe bodies, adapted for chasing prey. The tails are bushy and
4346-507: The coyote-sized Mesocyon of the Oligocene (38–24 Mya). These early canids probably evolved for the fast pursuit of prey in a grassland habitat; they resembled modern viverrids in appearance. Hesperocyonines eventually became extinct in the middle Miocene. One of the early Hesperocyonines, the genus Hesperocyon , gave rise to Archaeocyon and Leptocyon . These branches led to the borophagine and canine radiations . Around 8 Mya,
4428-449: The dogs. They found that females in heat searched out dominant males and were more likely to mate with a dominant male who appeared to be a quality leader. The females were more likely to reject submissive males. Furthermore, cases of male-male competition were more aggressive in the presence of high ranking females. This suggests that females prefer dominant males and males prefer high ranking females meaning social cues and status play
4510-481: The ear). Prohesperocyon probably had slightly longer limbs than its predecessors, and also had parallel and closely touching toes which differ markedly from the splayed arrangements of the digits in bears . Canidae soon divided into three subfamilies, each of which diverged during the Eocene: Hesperocyoninae (about 39.74–15 Mya), Borophaginae (about 34–32 Mya), and Caninae (about 34–30 Mya;
4592-458: The estimated bite force at the canine teeth of a large sample of living and fossil mammalian predators, when adjusted for their body mass, found that for placental mammals the bite force at the canines (in Newtons /kilogram of body weight) was greatest in the extinct dire wolf (163), followed among the modern canids by the four hypercarnivores that often prey on animals larger than themselves:
4674-402: The extant subfamily Caninae. This subfamily includes all living canids and their most recent fossil relatives. 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
4756-424: The extinct dire wolf. This indicates that these are both better adapted for cracking bone than other canids. A study of nine modern carnivores indicate that one in four adults had suffered tooth breakage and that half of these breakages were of the canine teeth. The highest frequency of breakage occurred in the spotted hyena, which is known to consume all of its prey including the bone. The least breakage occurred in
4838-500: The fathers also was shown to fluctuated depending on the level of care provided by the mother. Another study on parental investment showed that in free-ranging dogs, mothers modify their energy and time investment into their pups as they age. Due to the high mortality of free-range dogs at a young age a mother's fitness can be drastically reduced. This study found that as the pups aged the mother shifted from high-energy care to lower-energy care so that they can care for their offspring for
4920-399: The feeding of the litter occurs, the breeding success rate is higher than is the case where females split from the group and rear their pups in isolation. Young canids may take a year to mature and learn the skills they need to survive. In some species, such as the African wild dog, male offspring usually remain in the natal pack, while females disperse as a group and join another small group of
5002-469: The field of morphology was developed by Johann Wolfgang von Goethe (1790) and independently by the German anatomist and physiologist Karl Friedrich Burdach (1800). Among other important theorists of morphology are Lorenz Oken , Georges Cuvier , Étienne Geoffroy Saint-Hilaire , Richard Owen , Carl Gegenbaur and Ernst Haeckel . In 1830, Cuvier and Saint-Hilaire engaged in a famous debate , which
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#17327981678225084-404: The first identifiable member of the dog family had arisen. Named Prohesperocyon wilsoni , its fossils have been found in southwest Texas. The chief features which identify it as a canid include the loss of the upper third molar (part of a trend toward a more shearing bite), and the structure of the middle ear which has an enlarged bulla (the hollow bony structure protecting the delicate parts of
5166-435: The forefeet, but the pollex (thumb) is reduced and does not reach the ground. On the hind feet are four toes, but in some domestic dogs, a fifth vestigial toe, known as a dewclaw , is sometimes present, but has no anatomical connection to the rest of the foot. In some species, slightly curved nails are non-retractile and more-or-less blunt while other species have sharper, partially-retractile claws. The canine penis contains
5248-629: The genus Canis . The word "jackal" is applied to the golden jackal ( C. aureus ), found across southwestern and south-central Asia, and the Balkans in Europe. The first record of Canis on the African continent is Canis sp. A from South Turkwel, Kenya, dated 3.58–3.2 million years ago. In 2015, a study of mitochondrial genome sequences and whole genome nuclear sequences of African and Eurasian canids indicated that extant wolf-like canids have colonised Africa from Eurasia at least 5 times throughout
5330-640: The gray wolf, the coyote and the red fox, for sport. Canids such as the dhole are now endangered in the wild because of persecution, habitat loss, a depletion of ungulate prey species and transmission of diseases from domestic dogs. Canis Extant: Extinct: Canis is a genus of the Caninae which includes multiple extant species, such as wolves , dogs , coyotes , and golden jackals . Species of this genus are distinguished by their moderate to large size, their massive, well-developed skulls and dentition, long legs, and comparatively short ears and tails. The genus Canis ( Carl Linnaeus , 1758)
5412-496: The ground. However, based on skeletal details of the neck, at least some of the Borophaginae (such as Aelurodon ) are believed to have lacked this ligament. Dentition relates to the arrangement of teeth in the mouth, with the dental notation for the upper-jaw teeth using the upper-case letters I to denote incisors , C for canines , P for premolars , and M for molars , and the lower-case letters i, c, p and m to denote
5494-614: 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. Carnivorans evolved after the extinction of the non-avian dinosaurs 66 million years ago. Around 50 million years ago, or earlier, in the Paleocene , the Carnivora split into two main divisions: caniform (dog-like) and feliform (cat-like). By 40 Mya,
5576-559: The last common ancestor of the South American canids lived in North America some 4 Mya and more than one incursion across the new land bridge is likely given the fact that more than one lineage is present in South America. Two North American lineages found in South America are the gray fox ( Urocyon cinereoargentus ) and the now-extinct dire wolf ( Aenocyon dirus ). Besides these, there are species endemic to South America:
5658-486: The late Rancholabrean era across the Bering land bridge, with at least three separate invasions, with each one consisting of one or more different Eurasian gray wolf clades. MtDNA studies have shown that there are at least four extant C. lupus lineages. The dire wolf shared its habitat with the gray wolf, but became extinct in a large-scale extinction event that occurred around 11,500 years ago. It may have been more of
5740-543: The length and quality of the pelage vary with the season. The muzzle portion of the skull is much more elongated than that of the cat family. The zygomatic arches are wide, there is a transverse lambdoidal ridge at the rear of the cranium and in some species, a sagittal crest running from front to back. The bony orbits around the eye never form a complete ring and the auditory bullae are smooth and rounded. Females have three to seven pairs of mammae . All canids are digitigrade , meaning they walk on their toes. The tip of
5822-471: The mandibular symphysis in fossil carnivore specimens to determine what kind of hunter it was – a pack hunter or a solitary hunter – and even how it consumed its prey. The mandibles of canids are buttressed behind the carnassial teeth to crack bones with their post-carnassial teeth (molars M2 and M3). A study found that the modern gray wolf and the red wolf ( C. rufus ) possess greater buttressing than all other extant canids and
5904-407: The muscle and tendon of prey. Canids use their premolars for cutting and crushing except for the upper fourth premolar P4 (the upper carnassial) that is only used for cutting. They use their molars for grinding except for the lower first molar m1 (the lower carnassial) that has evolved for both cutting and grinding depending on the candid's dietary adaptation. On the lower carnassial the trigonid
5986-487: The nose is always naked, as are the cushioned pads on the soles of the feet. These latter consist of a single pad behind the tip of each toe and a more-or-less three-lobed central pad under the roots of the digits. Hairs grow between the pads and in the Arctic fox the sole of the foot is densely covered with hair at some times of the year. With the exception of the four-toed African wild dog ( Lycaon pictus ), five toes are on
6068-534: The only surviving subfamily). Members of each subfamily showed an increase in body mass with time and some exhibited specialized hypercarnivorous diets that made them prone to extinction. By the Oligocene , all three subfamilies (Hesperocyoninae, Borophaginae, and Caninae) had appeared in the fossil record of North America. The earliest and most primitive branch of the Canidae was Hesperocyoninae, which included
6150-535: The opposite sex to form a new pack. One canid, the domestic dog , entered into a partnership with humans a long time ago. The dog was the first domesticated species. The archaeological record shows the first undisputed dog remains buried beside humans 14,700 years ago, with disputed remains occurring 36,000 years ago. These dates imply that the earliest dogs arose in the time of human hunter-gatherers and not agriculturists . The fact that wolves are pack animals with cooperative social structures may have been
6232-558: The proestral period, increased levels of estradiol make the female attractive to the male. There is a rise in progesterone during the estral phase when female is receptive. Following this, the level of estradiol fluctuates and there is a lengthy dioestrous phase during which the female is pregnant. Pseudo-pregnancy often occurs in canids that have ovulated but failed to conceive. A period of anestrus follows pregnancy or pseudo-pregnancy, there being only one oestral period during each breeding season. Small and medium-sized canids mostly have
6314-608: The reason that the relationship developed. Humans benefited from the canid's loyalty, cooperation, teamwork, alertness and tracking abilities, while the wolf may have benefited from the use of weapons to tackle larger prey and the sharing of food. Humans and dogs may have evolved together. Among canids, only the gray wolf has widely been known to prey on humans. Nonetheless, at least two records of coyotes killing humans have been published, and at least two other reports of golden jackals killing children. Human beings have trapped and hunted some canid species for their fur and some, especially
6396-400: The tooth row also differs, with Beringian wolves having much higher frequencies of fracture for incisors, carnassials, and molars. A similar pattern was observed in spotted hyenas, suggesting that increased incisor and carnassial fracture reflects habitual bone consumption because bones are gnawed with the incisors and then cracked with the carnassials and molars. The gray wolf ( C. lupus ),
6478-409: The upper-case letters I to denote incisors , C for canines , P for premolars , and M for molars , and the lower-case letters i, c, p and m to denote the mandible teeth . Teeth are numbered using one side of the mouth and from the front of the mouth to the back. In carnivores , the upper premolar P4 and the lower molar m1 form the carnassials that are used together in a scissor-like action to shear
6560-576: The use of allometric engineering in which one or both species are manipulated to phenocopy the other species. A step relevant to the evaluation of morphology between traits/features within species, includes an assessment of the terms: homology and homoplasy . Homology between features indicates that those features have been derived from a common ancestor. Alternatively, homoplasy between features describes those that can resemble each other, but derive independently via parallel or convergent evolution . The invention and development of microscopy enabled
6642-709: The vulnerable individuals of large prey, and a pack of timber wolves can bring down a 500 kg (1,100 lb) moose. The genus Canis contains many different species and has a wide range of different mating systems that varies depending on the type of canine and the species. In a study done in 2017, it was found that in some species of canids females use their sexual status to gain food resources. The study looked at wolves and dogs. Wolves are typically monogamous and form pair-bonds ; whereas dogs are promiscuous when free-range and mate with multiple individuals. The study found that in both species females tried to gain access to food more and were more successful in monopolizing
6724-627: Was published in the 10th edition of Systema Naturae and included the dog-like carnivores: the domestic dog, wolves, coyotes and jackals. All species within Canis are phylogenetically closely related with 78 chromosomes and can potentially interbreed . In 1926, the International Commission on Zoological Nomenclature (ICZN) in Opinion 91 included Genus Canis on its Official Lists and Indexes of Names in Zoology . In 1955,
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