The even-toed ungulates are ungulates—hoofed animals—which bear weight equally on two of their five toes: the third and fourth. The other three toes are either present, absent, vestigial, or pointing posteriorly. By contrast, odd-toed ungulates bear weight on an odd number of the five toes. Another difference between the two is that many other even-toed ungulates digest plant cellulose in one or more stomach chambers rather than in their intestine as the odd-toed ungulates do.
Chevrotains, or mouse-deer, are small even-toed ungulates that make up the family Tragulidae, the only extant members of the infraorder Tragulina. The 10 extant species are placed in three genera, but several species also are known only from fossils. The extant species are found in forests in South and Southeast Asia, with a single species, the water chevrotain, in the rainforests of Central and West Africa. They are solitary or live in pairs, and feed almost exclusively on plant material. Chevrotains are the smallest hoofed mammals in the world. The Asian species weigh between 0.7 and 8.0 kg, while the African chevrotain is considerably larger at 7–16 kg (15–35 lb). With an average length of 45 cm (18 in) and an average height of 30 cm (12 in), the Java mouse-deer is the smallest extant (living) ungulate or hoofed mammal, as well as the smallest extant even-toed ungulate.
Tragelaphus is a genus of medium- to large-sized spiral-horned antelopes. It contains several species of bovine, all of which are relatively antelope-like. Species in this genus tend to be large sized, lightly built, have long necks and considerable sexual dimorphism. Elands, including the common eland, are embedded within this genus meaning that Taurotragus must be subsumed into Tragelaphus to avoid paraphyly. Alternatively, Taurotragus could be maintained as a separate genus, if the nyala and the lesser kudu are relocated to their own monospecific genera: respectively, Nyala and Ammelaphus. Other generic synonyms include Strepsiceros and Boocercus. The name "Tragelaphus" comes from the mythical tragelaph.
The Indian muntjac, also called the southern red muntjac and barking deer, is a deer species native to South and Southeast Asia. It is listed as Least Concern on the IUCN Red List.
The Javan rusa or Sunda sambar is a deer native to Indonesia and East Timor. Introduced populations exist in a wide variety of locations in the Southern Hemisphere.
The Barbary sheep, also known as aoudad is a species of caprine native to rocky mountains in North Africa. Six subspecies have been described. Although it is rare in its native North Africa, it has been introduced to North America, southern Europe, and elsewhere. It is also known in the Berber language as waddan or arwi, and in former French territories as the moufflon.
Taurotragus is a genus of large antelopes of the African savanna, commonly known as elands. It contains two species: the common eland T. oryx and the giant eland T. derbianus.
Cervus is a genus of deer that primarily are native to Eurasia, although one species occurs in northern Africa and another in North America. In addition to the species presently placed in this genus, it has included a whole range of other species now commonly placed in other genera. Additionally, the species-level taxonomy is in a state of flux.
The Philippine mouse-deer, also known as the Balabac chevrotain or pilandok, is a small, nocturnal ruminant, which is endemic to Balabac and nearby smaller islands southwest of Palawan in the Philippines. The genus Tragulus means 'little goat' and the Philippine mouse-deer has been named so due to the horizontal pupils of the eyes. This position of the pupil allows for an increase in peripheral depth perception. It has traditionally been considered a subspecies of the greater mouse-deer. In 2004, though, T. nigricans was separated from T. napu as its own species due to differences in skull morphology. Contrary to its common name, the Philippine mouse-deer does not belong to the deer family Cervidae, but is a member of the chevrotain family.
Habromys is a genus of rodent in the family Cricetidae, found in Mexico and Central America. It contains these species, all but one of which are threatened or endangered, five of them critically so. H. lophurus is near threatened.
Megadontomys is a genus of rodent in the family Cricetidae, found in Mexico. It contains the following species:
The Java mouse-deer is a species of even-toed ungulate in the family Tragulidae. When it reaches maturity it is about the size of a rabbit, making it the smallest living ungulate. It is found in forests in Java and perhaps Bali, although sightings there have not been verified.
The greater mouse-deer, greater Malay chevrotain, or napu is a species of even-toed ungulate in the family Tragulidae found in Sumatra, Borneo, and smaller Malaysian and Indonesian islands, and in southern Myanmar, southern Thailand, and peninsular Malaysia. Its natural habitat is subtropical or tropical, moist, lowland forest.
Hippotragus is a genus of antelopes which includes two living and one recently extinct species, as well as some fossil relatives. The name comes from Greek ἵππος (híppos), "horse", and τράγος (trágos), "he-goat".
Moschiola, the spotted chevrotains, are a genus of small even-toed ungulates in the family Tragulidae. They are found in forests in India, Sri Lanka and perhaps Nepal, and have pale-spotted or -striped upperparts unlike the other Asian members of the family, the mouse-deer of the genus Tragulus.
The lesser mouse-deer, lesser Malay chevrotain, or kanchil is a species of even-toed ungulate in the family Tragulidae.
The Vietnam mouse-deer, also known as the silver-backed chevrotain, is an even-toed ungulate in the family Tragulidae known only from Vietnam. It was first described in 1910 by British zoologist Oldfield Thomas, who procured four specimens from Nha Trang in Annam. Little is known about its distribution and ecology. After 1910, the Vietnam mouse-deer was reported next in 1990 near Dak Rong and Buon Luoi in the Gia Lai Province. With increasing hunting pressure, habitat loss due to deforestation and no more reports of the species in the wild, the mouse-deer was feared to have gone extinct. The IUCN listed the species as Data Deficient in 2008. In 2019, a study confirmed the presence of the Vietnam mouse-deer in dry low-lying forests of southern Vietnam with camera trap evidence. The mouse-deer is characterised by a rough coat with a strange double-tone coloration unseen in other chevrotains; the front part of the body is reddish brown and contrasts strongly with the greyish posterior. It has big reddish brown ears, white and dark reddish brown marks on the throat.
Williamson's mouse-deer is a species of even-toed ungulate in the family Tragulidae. It is found in Thailand, and possibly in China. The species is named after the collector Walter James Franklin Williamson.
