45-496: Tahrs ( / t ɑːr z / TARZ , / t ɛər z / TAIRZ ) or tehrs ( / t ɛər z / TAIRZ ) are large artiodactyl ungulates related to goats and sheep . There are three species, all native to Asia. Previously thought to be closely related to each other and placed in a single genus , Hemitragus , genetic studies have since proven that they are not so closely related and they are now considered as members of three separate monotypic genera: Hemitragus
90-419: A few bumps. In contrast, camels and ruminants have bumps that are crescent-shaped cusps ( selenodont ). Hippopotamidae † Trilobophorus Geze, 1985 Hippopotamidae is a family of stout, naked-skinned , and semiaquatic artiodactyl mammals, possessing three-chambered stomachs and walking on four toes on each foot. While they resemble pigs physiologically, their closest living relatives are
135-662: A population exists on Table Mountain in South Africa , descended from a pair of tahrs that escaped from a zoo in 1936, but most of these have been culled. As for the Nilgiri tahr, research indicates its presence to be in the mountain ranges of southern India. Totalling ~1400 individuals in 1998, its largest remaining population appears to survive between the Indian states of Tamil Nadu and Kerala, where it may be vulnerable to poachers and illegal hunting. A routine of feeding during
180-576: A similar aquatic lifestyle. Hippopotamuses appeared in the late Miocene and occupied Africa and Asia—they never got to the Americas. The camels ( Tylopoda ) were, during large parts of the Cenozoic , limited to North America; early forms like Cainotheriidae occupied Europe. Among the North American camels were groups like the stocky, short-legged Merycoidodontidae . They first appeared in
225-477: A simple stomach that digests food. Thus, they were grouped together as non-ruminants (Porcine). All other even-toed ungulates have molars with a selenodont construction (crescent-shaped cusps) and have the ability to ruminate , which requires regurgitating food and re-chewing it. Differences in stomach construction indicated that rumination evolved independently between tylopods and ruminants ; therefore, tylopods were excluded from Ruminantia . The taxonomy that
270-474: A slim build, lanky legs, and a long tail. Their hind legs were much longer than their front legs. The early to middle Eocene saw the emergence of the ancestors of most of today's mammals. Two formerly widespread, but now extinct, families of even-toed ungulates were Entelodontidae and Anthracotheriidae . Entelodonts existed from the middle Eocene to the early Miocene in Eurasia and North America. They had
315-473: A stocky body with short legs and a massive head, which was characterized by two humps on the lower jaw bone. Anthracotheres had a large, porcine ( pig -like) build, with short legs and an elongated muzzle . This group appeared in the middle Eocene up until the Pliocene , and spread throughout Eurasia, Africa, and North America. Anthracotheres are thought to be the ancestors of hippos, and, likewise, probably led
360-424: A very flexible body, contributing to their speed by increasing their stride length. Many even-toed ungulates have a relatively large head. The skull is elongated and rather narrow; the frontal bone is enlarged near the back and displaces the parietal bone , which forms only part of the side of the cranium (especially in ruminants). Four families of even-toed ungulates have cranial appendages. These Pecora (with
405-536: Is a stub . You can help Misplaced Pages by expanding it . Artiodactyl Cetartiodactyla Montgelard et al. 1997 Artiodactyls are placental mammals belonging to the order Artiodactyla ( / ˌ ɑːr t i oʊ ˈ d æ k t ɪ l ə / AR -tee-oh- DAK -tih-lə , from Ancient Greek ἄρτιος , ártios 'even' and δάκτυλος , dáktylos 'finger, toe'). Typically, they are ungulates which bear weight equally on two (an even number) of their five toes (the third and fourth, often in
450-560: Is given in the table below: The hippopotamids are descended from the anthracotheres , a family of semiaquatic and terrestrial artiodactyls that appeared in the late Eocene , and are thought to have resembled small- or narrow-headed hippos. The hippos split off from the anthracotheres some time during the Miocene . The oldest records of Hippopotamidae are from Afro-Arabia and date to the late Miocene, approximately 7.4 million years ago, expanding into Eurasia around 6 million years ago. After
495-475: Is more adapted to a squeezing mastication , which is characteristic of omnivores . Camels and ruminants have fewer teeth; there is often a yawning diastema , a designated gap in the teeth where the molars are aligned for crushing plant matter. The incisors are often reduced in ruminants, and are completely absent in the upper jaw . The canines are enlarged and tusk-like in the Suina, and are used for digging in
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#1732786796331540-822: Is now reserved for the Himalayan tahr , Nilgiritragus for the Nilgiri tahr , and Arabitragus for the Arabian tahr . While the Arabian tahr of Oman and the Nilgiri tahr of South India both have small ranges and are considered endangered , the Himalayan tahr remains relatively widespread in the Himalayas , and has been introduced to the Southern Alps of New Zealand , where it is hunted recreationally. Also,
585-411: Is relatively thin, so hippos dehydrate rapidly in dry environments. Both the incisors and canines are large and tusk-like, although the canine tusks are by far the larger. The tusks grow throughout life. The postcanine teeth are large and complex, suited for chewing the plant matter that comprises their diets. The number of incisors varies even within the same species, but the general dental formula
630-708: Is therefore focused on anthracotheres (family Anthracotheriidae); one dating from the Eocene to Miocene was declared to be "hippo-like" upon discovery in the 19th century. A study from 2005 showed that the anthracotheres and hippopotamuses had very similar skulls , but differed in the adaptations of their teeth. It was nevertheless believed that cetaceans and anthracothereres descended from a common ancestor, and that hippopotamuses developed from anthracotheres. A study published in 2015 confirmed this, but also revealed that hippopotamuses were derived from older anthracotherians. The newly introduced genus Epirigenys from Eastern Africa
675-525: Is thus the sister group of hippos. Linnaeus postulated a close relationship between camels and ruminants as early as the mid-1700s. Henri de Blainville recognized the similar anatomy of the limbs of pigs and hippos, and British zoologist Richard Owen coined the term "even-toed ungulates" and the scientific name "Artiodactyla" in 1848. Internal morphology (mainly the stomach and the molars) were used for classification. Suines (including pigs ) and hippopotamuses have molars with well-developed roots and
720-694: The Old World , exist today only in the Americas . South America was settled by even-toed ungulates only in the Pliocene, after the land bridge at the Isthmus of Panama formed some three million years ago. With only the peccaries, lamoids (or llamas ), and various species of capreoline deer , South America has comparatively fewer artiodactyl families than other continents, except Australia, which has no native species. The classification of artiodactyls
765-563: The cetaceans . They are sometimes referred to as hippopotamids . There are two living species of hippopotamid in two genera; the pygmy hippo, Choeropsis liberiensis of the forests of west Africa, and the common hippo, Hippopotamus amphibius . The term hippopotamus can also be applied to hippopotamids in general, although it is most frequently used for the common hippo and its respective genus . Hippopotamids are large mammals, with short, stumpy legs, and barrel-shaped bodies. They have large heads, with broad mouths, and nostrils placed at
810-507: The hind legs have a reduction in the number of toes to three. The central axis of the leg is between the third and fourth toe. The first toe is missing in modern artiodactyls, and can only be found in now-extinct genera. The second and fifth toes are adapted differently between species: When camels have only two toes present, the claws are transformed into nails (while both are made of keratin , claws are curved and pointed while nails are flat and dull). These claws consist of three parts:
855-412: The ruminants as the sister group of cetaceans. Subsequent studies established the close relationship between hippopotamuses and cetaceans; these studies were based on casein genes , SINEs , fibrinogen sequences, cytochrome and rRNA sequences, IRBP (and vWF ) gene sequences, adrenergic receptors , and apolipoproteins . In 2001, the fossil limbs of a Pakicetus (amphibioid cetacean
900-400: The appearance of the hippopotamids, the remaining anthracotheres went into a decline brought about by a combination of climatic change and competition with their descendants, until the last genus, Merycopotamus , died out in the early Pliocene of India. There were once many species of hippopotamid, but only two survive today: Hippopotamus amphibius , and Choeropsis liberiensis . They are
945-462: The early Eocene (about 53 million years ago). Since these findings almost simultaneously appeared in Europe , Asia , and North America , it is very difficult to accurately determine the origin of artiodactyls. The fossils are classified as belonging to the family Diacodexeidae ; their best-known and best-preserved member is Diacodexis . These were small animals, some as small as a hare , with
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#1732786796331990-609: The early Cenozoic ( Paleocene and Eocene ), which had hooves instead of claws on their feet. Their molars were adapted to a carnivorous diet, resembling the teeth in modern toothed whales , and, unlike other mammals, had a uniform construction. The suspected relations can be shown as follows: Artiodactyla [REDACTED] Mesonychia † [REDACTED] Cetacea [REDACTED] Molecular findings and morphological indications suggest that artiodactyls, as traditionally defined, are paraphyletic with respect to cetaceans. Cetaceans are deeply nested within
1035-419: The exception of the musk deer ), have one of four types of cranial appendages: true horns, antlers , ossicones , or pronghorns . True horns have a bone core that is covered in a permanent sheath of keratin, and are found only in the bovids . Antlers are bony structures that are shed and replaced each year; they are found in deer (members of the family Cervidae ). They grow from a permanent outgrowth of
1080-633: The form of a hoof ). The other three toes are either present, absent, vestigial , or pointing posteriorly. By contrast, most perissodactyls bear weight on an odd number of the five toes. Another difference between the two orders is that many artiodactyls (except for Suina ) digest plant cellulose in one or more stomach chambers rather than in their intestine (as perissodactyls do). Molecular biology, along with new fossil discoveries, has found that cetaceans ( whales , dolphins , and porpoises ) fall within this taxonomic branch, being most closely related to hippopotamuses . Some modern taxonomists thus apply
1125-1021: The former; the two groups together form a monophyletic taxon, for which the name Cetartiodactyla is sometimes used. Modern nomenclature divides Artiodactyla (or Cetartiodactyla) in four subordinate taxa: camelids (Tylopoda), pigs and peccaries (Suina), ruminants (Ruminantia), and hippos plus cetaceans (Whippomorpha). The presumed lineages within Artiodactyla can be represented in the following cladogram : Tylopoda (camels) [REDACTED] Suina (pigs) [REDACTED] Tragulidae (mouse deer) [REDACTED] Pecora (horn bearers) [REDACTED] Hippopotamidae (hippopotamuses) [REDACTED] Cetacea (whales) [REDACTED] The four summarized Artiodactyla taxa are divided into ten extant families: Although deer, musk deer, and pronghorns have traditionally been summarized as cervids (Cervioidea), molecular studies provide different—and inconsistent—results, so
1170-674: The frontal bone called the pedicle and can be branched, as in the white-tailed deer ( Odocoileus virginianus ), or palmate , as in the moose ( Alces alces ). Ossicones are permanent bone structures that fuse to the frontal or parietal bones during an animal's life and are found only in the Giraffidae . Pronghorns , while similar to horns in that they have keratinous sheaths covering permanent bone cores, are deciduous. All these cranial appendages can serve for posturing, battling for mating privilege, and for defense. In almost all cases, they are sexually dimorphic, and are often found only on
1215-689: The genus Hexaprotodon , which is now largely restricted to South Asia and Southeast Asia, formerly included many fossil hippopotamuses that are now thought to be unrelated. Hippopotamidae's placement within Artiodactyla can be represented in the following cladogram : Tylopoda (camels and kin) [REDACTED] Suina (pigs and kin) [REDACTED] Ruminantia (ruminants) [REDACTED] Hippopotamidae (hippopotamids) [REDACTED] Cetacea (whales) [REDACTED] The lower canine teeth of hippopotamids are similar in function and structure to
1260-401: The ground and for defense. In ruminants, the males' upper canines are enlarged and used as a weapon in certain species (mouse deer, musk deer, water deer ); species with frontal weapons are usually missing the upper canines. The lower canines of ruminants resemble the incisors, so that these animals have eight uniform teeth in the frontal part of the lower jaw . The molars of porcine have only
1305-432: The last survivors of two major evolutionary lineages, the hippos proper and the pygmy hippos, respectively; these lineages could arguably be considered subfamilies , but their relationship to each other – apart from being fairly distant relatives – is not well resolved. The enigmatic Miocene Kenyapotamus is insufficiently known to be assigned a place in the hippo phylogeny with any degree of certainty. In addition,
1350-601: The late Eocene and developed a great diversity of species in North America. Only in the late Miocene or early Pliocene did they migrate from North America into Eurasia. The North American varieties became extinct around 10,000 years ago. Suina (including pigs ) have been around since the Eocene. In the late Eocene or the Oligocene , two families stayed in Eurasia and Africa; the peccaries , which became extinct in
1395-407: The limbs are predominantly localized, which ensures that artiodactyls often have very slender legs. A clavicle is never present, and the scapula is very agile and swings back and forth for added mobility when running. The special construction of the legs causes the legs to be unable to rotate, which allows for greater stability when running at high speeds. In addition, many smaller artiodactyls have
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1440-634: The males are consistently larger and heavier than the females. In deer, only the males boast antlers, and the horns of bovines are usually small or not present in females. Male Indian antelopes have a much darker coat than females. Almost all even-toed ungulates have fur, with the exception being the nearly hairless hippopotamus. Fur varies in length and coloration depending on the habitat. Species in cooler regions can shed their coat. Camouflaged coats come in colors of yellow, gray, brown, or black tones. Even-toed ungulates bear their name because they have an even number of toes (two or four)—in some peccaries,
1485-463: The males. One exception is the species Rangifer tarandus , known as reindeer in Europe or caribou in North America, where both sexes can grow antlers yearly, though the females' antlers are typically smaller and not always present. There are two trends in terms of teeth within Artiodactyla. The Suina and hippopotamuses have a relatively large number of teeth (with some pigs having 44); their dentition
1530-519: The morning followed by a long rest period, then feeding in the evening, constitutes the tahr's daily routine. Tahrs are not generally active or feed at night and can be found at the same location morning and evening. Nilgiri Tahr is the state animal of Tamil Nadu . It has references from Tamil Sangam Literature like Cilappatikaram and Cīvaka Cintāmaṇi . In 2023, Tamil nadu government has declared October 7 as Nilgiri Tahr Day in honour of E. R. C. Davidar This article about an even-toed ungulate
1575-421: The mouse deer, often reaches a body length of only 45 centimeters (18 in) and a weight of 1.5 kilograms (3.3 lb). The largest member, the hippopotamus, can grow up to 5 meters (16 ft) in length and weigh 4.5 metric tons (5 short tons), and the giraffe can grow to be 5.5 meters (18 ft) tall and 4.7 meters (15 ft) in body length. All even-toed ungulates display some form of sexual dimorphism :
1620-948: The name Cetartiodactyla ( / s ɪ ˌ t ɑːr t i oʊ ˈ d æ k t ɪ l ə / ) to this group, while others opt to include cetaceans within the existing name of Artiodactyla. Some researchers use " even-toed ungulates " to exclude cetaceans and only include terrestrial artiodactyls, making the term paraphyletic in nature. The roughly 270 land-based even-toed ungulate species include pigs , peccaries , hippopotamuses , antelopes , deer , giraffes , camels , llamas , alpacas , sheep , goats and cattle . Many are herbivores, but suids are omnivorous, whereas cetaceans are entirely carnivorous. Artiodactyls are also known by many extinct groups such as anoplotheres , cainotheriids , merycoidodonts , entelodonts , anthracotheres , basilosaurids , and palaeomerycids . Many artiodactyls are of great dietary, economic, and cultural importance to humans. The oldest fossils of even-toed ungulates date back to
1665-442: The plate (top and sides), the sole (bottom), and the bale (rear). In general, the claws of the forelegs are wider and blunter than those of the hind legs, and they are farther apart. Aside from camels, all even-toed ungulates put just the tip of the foremost phalanx on the ground. In even-toed ungulates, the bones of the stylopodium (upper arm or thigh bone) and zygopodiums (tibia and fibula) are usually elongated. The muscles of
1710-413: The question of phylogenetic systematics of infraorder Pecora (the horned ruminants) for the time being, cannot be answered. Artiodactyls are generally quadrupeds . Two major body types are known: suinids and hippopotamuses are characterized by a stocky body, short legs, and a large head; camels and ruminants, though, have a more slender build and lanky legs. Size varies considerably; the smallest member,
1755-472: The sequence with that of other living beings—the more similar they are, the more closely they are related. Comparison of even-toed ungulate and cetaceans genetic material has shown that the closest living relatives of whales and hippopotamuses is the paraphyletic group Artiodactyla. Dan Graur and Desmond Higgins were among the first to come to this conclusion, and included a paper published in 1994. However, they did not recognize hippopotamuses and classified
1800-668: The size of a wolf) and Ichthyolestes (an early whale the size of a fox) were found in Pakistan. They were both archaeocetes ("ancient whales") from about 48 million years ago (in the Eocene). These findings showed that archaeocetes were more terrestrial than previously thought, and that the special construction of the talus (ankle bone) with a double-rolled joint surface, previously thought to be unique to even-toed ungulates, were also in early cetaceans. The mesonychians , another type of ungulate, did not show this special construction of
1845-521: The talus, and thus was concluded to not have the same ancestors as cetaceans. The oldest cetaceans date back to the early Eocene (53 million years ago), whereas the oldest known hippopotamus dates back only to the Miocene (15 million years ago). The hippopotamids are descended from the anthracotheres, a family of semiaquatic and terrestrial artiodactyls that appeared in the late Eocene, and are thought to have resembled small- or narrow-headed hippos. Research
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1890-452: The top of their snouts. Like pigs, they have four toes, but unlike pigs, all of the toes are used in walking. Hippopotamids are unguligrade , although, unlike most other such animals, they have no hooves, instead using a pad of tough connective tissue on each foot. Their stomachs have three chambers, but they are not true ruminants . The living species are smooth-skinned and lack both sebaceous glands and sweat glands . The outer epidermis
1935-479: The traditional order Artiodactyla and infraorder Cetacea are sometimes subsumed into the more inclusive Cetartiodactyla taxon. An alternative approach is to include both land-dwelling even-toed ungulates and ocean-dwelling cetaceans in a revised Artiodactyla taxon. In the 1990s, biological systematics used not only morphology and fossils to classify organisms, but also molecular biology . Molecular biology involves sequencing an organism's DNA and RNA and comparing
1980-426: Was hotly debated because ocean-dwelling cetaceans evolved from land-dwelling even-toed ungulates. Some semiaquatic even-toed ungulates ( hippopotamuses ) are more closely related to ocean-dwelling cetaceans than to other even-toed ungulates. Phylogenetic classification only recognizes monophyletic taxa; that is, groups that descend from a common ancestor and include all of its descendants. To address this problem,
2025-621: Was widely accepted by the end of the 20th century was: Suidae [REDACTED] Hippopotamidae [REDACTED] Tylopoda [REDACTED] Tragulidae [REDACTED] Pecora [REDACTED] Modern cetaceans are highly adapted sea creatures which, morphologically, have little in common with land mammals; they are similar to other marine mammals , such as seals and sea cows , due to convergent evolution . However, they evolved from originally terrestrial mammals. The most likely ancestors were long thought to be mesonychians—large, carnivorous animals from
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