Artiodactyla in the context of Intestine

Sheep (pl.: sheep) or domestic sheep (Ovis aries) are a domesticated, ruminant mammal typically kept as livestock. Although the term sheep can apply to other species in the genus Ovis, in everyday usage it almost always refers to domesticated sheep. Like all ruminants, sheep are members of the order Artiodactyla, the even-toed ungulates. Numbering a little over one billion, domestic sheep are also the most numerous species of sheep. An adult female is referred to as a ewe (/juː/ yoo), an intact male as a ram, occasionally a tup, a castrated male as a wether, and a young sheep as a lamb.

Sheep are most likely descended from the wild mouflon of Europe and Asia, with Iran being a geographic envelope of the domestication center. One of the earliest animals to be domesticated for agricultural purposes, sheep are raised for fleeces, meat (lamb, hogget, or mutton), and milk. A sheep's wool is the most widely used animal fiber, and is usually harvested by shearing. In Commonwealth countries, ovine meat is called lamb when from younger animals and mutton when from older ones; in the United States, meat from both older and younger animals is usually called lamb. Sheep continue to be important for wool and meat today, and are also occasionally raised for pelts, as dairy animals, or as model organisms for science.

Cetaceans (/sɪˈteɪʃə/; from Latin cetus 'whale', from Ancient Greek κῆτος (kêtos) 'huge fish, sea monster') are aquatic mammals belonging to the infraorder Cetacea, in the order Artiodactyla. Cetaceans include whales, dolphins and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel themselves through the water with powerful up-and-down movements of their tail, which ends in a paddle-like fluke, using their flipper-shaped forelimbs to steer.

While the majority of cetaceans live in marine environments, a small number reside solely in brackish or fresh water. Having a cosmopolitan distribution, they can be found in some rivers and all of Earth's oceans, and many species migrate throughout vast ranges with the changing of the seasons.

Ungulates are members of the diverse clade Euungulata, which primarily consists of large mammals with hooves. Once part of the taxon "Ungulata" along with paenungulates and tubulidentates, as well as several extinct taxa, "Ungulata" has since been determined to be a polyphyletic grouping based on molecular data. As a result, true ungulates had since been reclassified to the newer clade Euungulata in 2001 within the clade Laurasiatheria, while Paenungulata and Tubulidentata had been reclassified to the distant clade Afrotheria. Alternatively, some authors use the name Ungulata to designate the same clade as Euungulata.

Living ungulates are divided into two orders: Perissodactyla including equines, rhinoceroses, and tapirs; and Artiodactyla including cattle, antelope, pigs, giraffes, camels, sheep, deer, and hippopotamuses, among others. Cetaceans such as whales, dolphins, and porpoises are also classified as artiodactyls, although they do not have hooves. Most terrestrial ungulates use the hoofed tips of their toes to support their body weight while standing or moving. Two other orders of ungulates, Notoungulata and Litopterna, both native to South America, became extinct at the end of the Pleistocene, around 12,000 years ago.

River dolphins are a polyphyletic group of fully aquatic mammals that reside exclusively in freshwater or brackish water. They are an informal grouping of dolphins, which itself is a paraphyletic group within the infraorder Cetacea. Extant river dolphins are placed in two superfamilies, Platanistoidea and Inioidea. They comprise the families Platanistidae (the South Asian dolphins), the possibly extinct Lipotidae (Yangtze River dolphin), Iniidae (the Amazonian dolphins) and Pontoporiidae. There are five extant species of river dolphins. River dolphins, alongside other cetaceans, belong to the clade Artiodactyla, with even-toed ungulates, and their closest living relatives the hippopotamuses, from which they diverged about 40 million years ago. Specific types of dolphins can be pink.

River dolphins are relatively small compared to other dolphins, having evolved to survive in warm, shallow water and strong river currents. They range in size from the 5-foot (1.5 m) long South Asian river dolphin to the 8-foot (2.4 m) and 220-pound (100 kg) Amazon river dolphin. Several species exhibit sexual dimorphism, in that the females are larger than the males. They have streamlined bodies and two limbs that are modified into flippers. River dolphins use their conical-shaped teeth and long beaks to capture fast-moving prey in murky water. They have well-developed hearing that is adapted for both air and water; they do not really rely on vision since their eyes are very small and the water they swim in is usually very muddy. Instead, they tend to rely on echolocation when hunting and navigating. These species are well-adapted to living in warm, shallow waters, and, unlike other cetaceans, have little to no blubber.

Peccaries (also javelinas or skunk pigs) are pig-like ungulates of the family Tayassuidae (New World pigs). They are found throughout Central and South America, Trinidad in the Caribbean, and in the southwestern area of North America. Peccaries usually measure between 90 and 130 cm (2 ft 11 in and 4 ft 3 in) in length, and a full-grown adult usually weighs about 20 to 40 kg (44 to 88 lb). They represent the closest relatives of the family Suidae, which contains pigs and relatives. Together Tayassuidae and Suidae are grouped in the suborder Suina within the order Artiodactyla (even-toed ungulates).

Peccaries are social creatures that live in herds. They are omnivores and eat roots, grubs, and a variety of other foods. They can identify each other by their strong odors. A group of peccaries that travel and live together is called a squadron. A squadron of peccaries averages between six and nine members. They give birth year-round to an average litter of two.

A cloven hoof, cleft hoof, divided hoof, or split hoof is a hoof split into two toes. Members of the mammalian order Artiodactyla that possess this type of hoof include pigs(suborder Suina), as well as cattle, deer, antelopes, gazelles, goats, and sheep (suborder Ruminantia).

The two digits of cloven-hooved animals are homologous to the third and fourth fingers of the hand. They are called claws and are named for their relative location on the foot: the outer, or lateral, claw and the inner, or medial claw. The space between the two claws is called the interdigital cleft; the area of skin is called the interdigital skin. The hard outer covering of the hoof is called the hoof wall or horn. It is a hard surface, similar to the human fingernail.

Laurasiatheria (/lɔːrˌeɪʒəˈθɪəriə, -θɛriə/; "Laurasian beasts") is a superorder of placental mammals that groups together true insectivores (eulipotyphlans), bats (chiropterans), carnivorans, pangolins (pholidotes), even-toed ungulates (artiodactyls), odd-toed ungulates (perissodactyls), and all their extinct relatives (pan-euungulates). From systematics and phylogenetic perspectives, it is subdivided into order Eulipotyphla and clade Scrotifera. It is a sister group to Euarchontoglires with which it forms the magnorder Boreoeutheria. Laurasiatheria was discovered on the basis of the similar gene sequences shared by the mammals belonging to it; no anatomical features have yet been found that unite the group, although a few have been suggested such as a small coracoid process, a simplified hindgut (reversed in artiodactyls), high intelligence, lack of grasping hands (though mimicry of grasping is observed in felines) and allantoic vessels that are large to moderate in size. The Laurasiatheria clade is based on DNA sequence analyses and retrotransposon presence/absence data. The superorder originated on the northern supercontinent of Laurasia, after it split from Gondwana when Pangaea broke up. Its last common ancestor is supposed to have lived between ca. 76 to 90 million years ago.

The Antilocapridae are a family of ruminant artiodactyls endemic to North America. Their closest extant relatives are the giraffids. Only one species, the pronghorn (Antilocapra americana), is living today; all other members of the family are extinct. The living pronghorn is a small ruminant mammal resembling an antelope.

The mountain goat (Oreamnos americanus), also known as the Rocky Mountain goat, is a cloven-footed mammal that is endemic to the remote and rugged mountainous areas of western North America. A subalpine to truly alpine species, it is a sure-footed climber commonly seen on sheer rock faces, near-vertical cliffs and icy passages. Mountain goats generally avoid venturing down into lower elevations—except during seasonal food shortages or during particularly bad weather—as the extreme elevation of their habitat is the primary defense against predators such as black and brown bears, pumas and wolves.

Despite its vernacular name and both genera being in the same subfamily (Caprinae), the mountain goat is not a member of Capra, the genus that includes all true goats (such as the wild goat (Capra aegagrus), from which the domestic goat is derived); rather, it is more closely allied with the other bovids known as "goat-antelopes", including the European chamois (Rupicapra), the gorals (Naemorhedus), the takins (Budorcas) and the serows (Capricornis), of Japan and eastern South Asia.

Ungulates are members of the diverse clade Euungulata, which primarily consists of large mammals with hooves. Once part of the taxon "Ungulata" along with paenungulates and tubulidentates, as well as several extinct taxa, "Ungulata" has since been determined to be a polyphyletic grouping based on molecular data. As a result, true ungulates have since been reclassified to the newer clade Euungulata in 2001 within the clade Laurasiatheria, while Paenungulata and Tubulidentata have been reclassified to the distant clade Afrotheria. Alternatively, some authors use the name Ungulata to designate the same clade as Euungulata.

Living ungulates are divided into two orders: Perissodactyla including equines, rhinoceroses, and tapirs; and Artiodactyla including cattle, antelope, pigs, giraffes, camels, sheep, deer, and hippopotamuses, among others. Cetaceans such as whales, dolphins, and porpoises are also classified as artiodactyls, although they do not have hooves. Most terrestrial ungulates use the hoofed tips of their toes to support their body weight while standing or moving. Two other orders of ungulates, Notoungulata and Litopterna, both native to South America, became extinct at the end of the Pleistocene, around 12,000 years ago.