Caniformia is a suborder within the order Carnivora consisting of "dog-like" carnivorans. They include dogs (wolves, foxes, etc.), bears, raccoons, and mustelids.[1] The Pinnipedia (seals, walruses and sea lions) are also assigned to this group. The center of diversification for the Caniformia is North America and northern Eurasia. Caniformia stands in contrast to the other suborder of Carnivora, the Feliformia ("cat-like" carnivorans), the center of diversification of which was in Africa and southern Asia.
Most members of this group have nonretractile claws (the fisher,[2]marten,[3]sea otter (forepaws only),[4]red panda,[5] and ringtail, and some foxes have retractile or semi-retractile claws[6]) and tend to be plantigrade (with the exception of the Canidae). Other traits that separate the Caniformia from the Feliformia is that caniforms have longer jaws and more teeth, with less specialized carnassial teeth. They also tend more towards omnivory and opportunistic feeding, while the feliforms, other than the viverrids, are more specialized for eating meat. Caniforms have single-chambered or partially divided auditory bullae, composed of a single bone, while in feliforms, the auditory bullae are double-chambered, composed of two bones joined by a septum.[7] In the Caniformia, the bulbourethral glands and vesicula seminalis are always absent. Relative to body size, the baculum is usually longer in the Caniformia than in the Feliformia.[7]
Caniformia consists of nine extant families, with three extinct families also recognized. The extant families are monophyletic according to phylogenetic molecular analysis.[8] Terrestrial caniforms in the wild are found on all continents with the exception of Antarctica, while pinnipeds are distributed throughout the world's oceans.
Family Canidae (dogs and other canids) includes wolves, dogs, coyotes, and foxes, as well as a number of less familiar animals. The family is currently divided into two major groups, the true dogs (tribe Canini), which includes nine genera, and the true foxes (tribe Vulpini) with two genera. In addition, two basal genera are described. About 35 species of extant canids are currently recognized. Canids are the most social of all caniforms, sometimes living in packs. The dog is the most diverse of all mammals in terms of body structure variants.[citation needed]
Family Ursidae (bears) is the largest of all the land caniforms. Eight species are recognized, divided into five genera. They range from the large polar bear (350–680 kilograms (770–1,500lb) in males) to the small sun bear (30–60 kilograms (66–132lb) in males) and from the endangered giant panda to the very common black bear. Common characteristics of modern bears include a large body with stocky legs, a long snout, shaggy hair, plantigrade paws with five nonretractile claws, and a short tail. Most bears are omnivorous, with largely varied diets that include both plants and animals. The polar bear is the most carnivorous of bears due to the arctic climate in which it lives, and shows a preference for eating seals. The giant panda is the most herbivorous bear and has evolved a number of adaptations, including a sixth "toe", specialized teeth, and strong jaw muscles, to allow it to feed nearly exclusively on bamboo, a tough member of the grass family. The sloth bear has some adaptations for ant and termite eating, with a long snout, powerful claws, and missing upper front teeth, though it also eats honey and fruit.
Family Ailuridae consists today of a single species, the red panda, which was once thought to be included in the Procyonidae or Ursidae lineages, but is now placed in its own family along with a number of extinct species. It is found in the Himalayas, including southern China, Nepal, Bhutan, India, and Pakistan. Fossil species of the family are also found in North America.[9]
Family Mephitidae (skunks and stink badgers) was once classified as mustelids, but are now recognized as a lineage in their own right. The 12 species of skunks are divided into four genera: Mephitis (hooded and striped skunks, two species), Spilogale (spotted skunks, four species), Mydaus (stink badgers, two species) and Conepatus (hog-nosed skunks, four species). The two skunk species in the genus Mydaus inhabit Indonesia and the Philippines; all other skunks inhabit the Americas from Canada to central South America.
Family Mustelidae (badgers, weasels and otters) is the largest family of carnivora, with 22 extant genera and roughly 57 extant species. While highly variable in shape, size, and behavior, most mustelids are smaller animals with short legs, short, round ears, and thick fur. Mustelids are predominantly carnivorous. While not all share identical dentition, they all possess teeth adapted for eating flesh, including the presence of shearing carnassials.
Members of Family Procyonidae (raccoons, coatis) are smallish animals, with generally slender bodies and long tails. Nineteen extant species in six genera are currently recognized. Except for the kinkajou, all procyonids have banded tails and distinct facial markings, and like bears, are plantigrade, walking on the soles of their feet. Most species have nonretractile claws. Early procyonids may have been an offshoot of the canids that adapted to more omnivorous diets.[10]
Pinnipedia (seals, sea lions, and walruses clade) is a widely distributed and diverse group of semiaquatic marine mammals which is closely related to an extinct group of pinnipeds, Enaliarctos. While support for the monophyly of pinnipeds is strong, the relationship of pinnipeds to terrestrial mammals is still unclear. Some studies support the hypothesis that the bears are their closest relatives,[11][12][13] while others support a closer relationship to the mustelids.[14][15][16][17]
Pinnipeds split from other caniforms 50 million years ago (Mya) during the Eocene.[16]
The clade is currently divided into three families:
Family Phocidae (true or earless seals) consists of around 19 species of highly aquatic, barrel-shaped animals ranging from 45kg (100lb) and 1.2m (4ft) in length (the ringed seal), to 2,400kg (5,300lb) and 5m (16ft) (southern elephant seal). Phocids are found throughout the world's oceans.
Family Otariidae (eared seals, sea lions, fur seals) is distributed throughout the world's oceans with the exception of the North Atlantic. The 15 species (divided into seven genera) of otariids are distinguished from phocids by visible external ears (pinnae), more dog-like faces, and the ability to turn their rear flippers forward.
Miacis is the earliest known member of the order Carnivora.
Evolution
Caniforms first appeared as tree-climbing, superficially marten-like carnivores in the Eocene around 42 Mya. Miacis cognitus was probably an early caniform. Like many other early carnivorans it was well suited for tree climbing with needle-sharp claws, and had limbs and joints that resemble those of modern carnivorans. M. cognitus was probably a very agile forest dweller that preyed on smaller animals, such as small mammals, reptiles, and birds.
Debate continues on the origin of pinnipeds. Recent molecular evidence suggests pinnipeds evolved from a bear-like ancestor about 23 Mya during the lateOligocene or early Miocene epochs, a transitional period between the warmer Paleogene and cooler Neogeneperiods.[15] However, discovery of the fossil Puijila darwini in early Miocene deposits in Nunavut suggests a different scenario. Like a modern otter, Puijila had a long tail, short limbs, and webbed feet instead of flippers. However, its limbs and shoulders were more robust, and Puijila likely had been a quadrupedal swimmer–retaining a form of aquatic locomotion that give rise to the major swimming types employed by modern pinnipeds. Puijila has been assigned to a clade of mustelids.
The cladogram is based on molecular phylogeny of six genes in Flynn (2005),[15] with the musteloids updated following the multigene analysis of Law et al. (2018).[18]
Bears are carnivoran mammals of the family Ursidae. They are classified as caniforms, or doglike carnivorans. Although only eight species of bears are extant, they are widespread, appearing in a wide variety of habitats throughout most of the Northern Hemisphere and partially in the Southern Hemisphere. Bears are found on the continents of North America, South America, and Eurasia. Common characteristics of modern bears include large bodies with stocky legs, long snouts, small rounded ears, shaggy hair, plantigrade paws with five nonretractile claws, and short tails.
Carnivora is an order of placental mammals that have specialized in primarily eating flesh, whose members are formally referred to as carnivorans. The order Carnivora is the fifth largest order of mammals, comprising at least 279 species.
The earless seals, phocids, or true seals are one of the three main groups of mammals within the seal lineage, Pinnipedia. All true seals are members of the family Phocidae. They are sometimes called crawling seals to distinguish them from the fur seals and sea lions of the family Otariidae. Seals live in the oceans of both hemispheres and, with the exception of the more tropical monk seals, are mostly confined to polar, subpolar, and temperate climates. The Baikal seal is the only species of exclusively freshwater seal.
The Mustelidae are a diverse family of carnivorous mammals, including weasels, stoats, badgers, otters, martens, grisons, and wolverines. Otherwise known as mustelids, they form the largest family in the suborder Caniformia of the order Carnivora with about 66 to 70 species in nine subfamilies.
Pinnipeds, commonly known as seals, are a widely distributed and diverse clade of carnivorous, fin-footed, semiaquatic, mostly marine mammals. They comprise the extant families Odobenidae, Otariidae, and Phocidae, with 34 extant species and more than 50 extinct species described from fossils. While seals were historically thought to have descended from two ancestral lines, molecular evidence supports them as a monophyletic lineage. Pinnipeds belong to the suborder Caniformia of the order Carnivora; their closest living relatives are musteloids, having diverged about 50 million years ago.
Fissipedia is a former suborder of placental mammals comprising the largely land-based families of the order Carnivora. In some former taxonomic classifications, Pinnipedia is treated as an suborder in order Carnivora along side Fissipedia and Creodonta,. rather than as a subgroup of "dog-like" carnivorans.
Ailuridae is a family in the mammal order Carnivora. The family consists of the red panda and its extinct relatives.
Potamotherium an extinct genus of caniform carnivoran from the Miocene epoch of France and Germany. It has historically been assigned to the family Mustelidae, but more recent studies suggest that it represents a primitive relative of pinnipeds
Enaliarctos is an extinct genus of pinnipedimorph, and may represent the ancestor to all pinnipeds. Prior to the discovery of Puijila, the five species in the genus Enaliarctos represented the oldest known pinnipedimorph fossils, having been recovered from late Oligocene and early Miocene strata of California and Oregon.
Feliformia is a suborder within the order Carnivora consisting of "cat-like" carnivorans, including cats, hyenas, mongooses, viverrids, and related taxa. Feliformia stands in contrast to the other suborder of Carnivora, Caniformia.
Ursoidea is a superfamily of arctoid carnivoran mammals that includes the families Subparictidae, Amphicynodontidae, and Ursidae. The last family includes the extant lineages of bears, as well as the extinct Hemicyoninae and Ursavinae.
Musteloidea is a superfamily of carnivoran mammals united by shared characteristics of the skull and teeth. Musteloids are the sister group of pinnipeds, the group which includes seals.
Arctoidea is a clade of mostly carnivorous mammals which include the extinct Hemicyonidae (dog-bears), and the extant Musteloidea, Pinnipedia, and Ursidae (bears), found in all continents from the Eocene, 46 million years ago, to the present. The oldest group of the clade is the bears, as their CMAH gene is still intact. The gene became non-functional in the common ancestor of the Mustelida. Arctoids are caniforms, along with dogs (canids) and extinct bear dogs (Amphicyonidae). The earliest caniforms were superficially similar to martens, which are tree-dwelling mustelids. Together with feliforms, caniforms compose the order Carnivora; sometimes Arctoidea can be considered a separate suborder from Caniformia and a sister taxon to Feliformia.
Amphicynodontidae is a probable clade of extinct arctoids. While some researchers consider this group to be an extinct subfamily of bears, a variety of morphological evidence links amphicynodontines with pinnipeds, as the group were semi-aquatic otter-like mammals. In addition to the support of the pinniped–amphicynodontine clade, other morphological and some molecular analyses support bears being the closest living relatives to pinnipeds. According to McKenna and Bell (1997) Amphicynodontinae are classified as stem-pinnipeds in the superfamily Phocoidea. Fossils of these mammals have been found in Europe, North America and Asia. Amphicynodontines should not be confused with Amphicyonids (bear-dogs), a separate family of Carnivora which is a sister clade to arctoids within the caniforms, but which may be listed as a clade of extinct arctoids in older publications.
Pinnipedimorpha is a clade of arctoid carnivorans that is defined to include the last common ancestor of Phoca and Enaliarctos, and all descendants of that ancestor. Scientists still debate on which lineage of arctoid carnivorans are the closest relatives to the pinnipedimorphs, being more closely related to musteloids.
Simocyoninae is an extinct subfamily of Ailuridae. The taxonomic history of this group was complicated, as researchers placed various fossil caniform genera into the subfamily. In addition to Simocyon, there was also Oligobunis, Cephalogale, and Enhydrocyon. This subfamily was initially classified within the Canidae or dog family. This idea went even further in 1910 when American paleontologist Henry Fairfield Osborn considered dholes, African wild dogs, and bush dogs to be the only extant representation left of the simocyonines. This was in large part to the overall similarity in the morphology of their molars, which suggested a shared ancestry of hypercarnivory. This view point was not supported by European paleontologists who believed that Simocyon was more closely related to musteloids. Soon the Simocyoninae were found as extinct subfamily of procyonids, or members of the raccoon-family, due to similarity of the basicranium of these animals. This was supported by subsequent researchers. It was not until a more completed skull of a Simocyon found in north Shaanxi, China was described by Wang (1997) who found that Simocyoninae is closely related Ailurinae on the basis of cranial and dental characteristics.
Subparictidae is an extinct family of early Paleogene arctoid carnivorans endemic to North America that closely related to bears. They were small, raccoon-like mammals that lived from the Eocene to the early Miocene. This family includes a handful of genera such as Subparictis, Parictis, Nothocyon, and Eoarctos.
↑ Rhines, C (2003). "Martes pennanti". Animal Diversity Web. Retrieved March 12, 2011.
↑ "American Marten". New York State Department of Environmental Conservation. Retrieved March 12, 2011.
↑ Silverstein, Alvin; Silverstein, Virginia and Robert (1995). The Sea Otter. Brookfield, Connecticut: The Millbrook Press, Inc. ISBN978-1-56294-418-6. OCLC 30436543. p11.
↑ Lento, G. M.; Hickson, R. E.; Chambers, G. K.; Penny, D. (1995). "Use of spectral analysis to test hypotheses on the origin of pinnipeds". Molecular Biology and Evolution. 12 (1): 28–52. doi:10.1093/oxfordjournals.molbev.a040189. PMID7877495.
↑ Sato, J. J.; Wolsan, M.; Suzuki, H.; Hosoda, T.; Yamaguchi, Y.; Hiyama, K.; Kobayashi, M.; Minami, S. (2006). "Evidence from nuclear DNA sequences sheds light on the phylogenetic relationships of Pinnipedia: Single origin with affinity to Musteloidea". Zoological Science. 23 (2): 125–46. doi:10.2108/zsj.23.125. hdl:2115/13508. PMID16603806. S2CID25795496.
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