|Family:|| Tragulidae |
H. Milne-Edwards, 1864
| Tragulus |
Chevrotains, or mouse-deer, are diminutive, even-toed ungulates that make up the family Tragulidae, and are the only living 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; a single species, the water chevrotain, is found in the rainforests of Central and West Africa.  They are solitary, or live in loose groupings or 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 (1+1⁄2 and 17+3⁄4 lb), 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 surviving ungulate (hoofed) mammal, as well as the smallest artiodactyl (even-toed ungulate).  Despite their common name of "mouse deer", they are actually not true deer at all (Cervidae), but form a unique family of bovids closer in lineage to cattle or antelope.
In November 2019, conservation scientists announced that they had photographed silver-backed chevrotains (Tragulus versicolor) in a Vietnamese forest for the first time since the last confirmed sightings in 1990.   
The word "chevrotain" comes from the Middle French word chevrot (kid or fawn), derived from chèvre (goat). 
The single African species is consistently known as "chevrotain".    The names "chevrotain" and "mouse-deer" have been used interchangeably among the Asian species,     though recent authorities typically have preferred chevrotain for the species in the genus Moschiola and mouse-deer for the species in the genus Tragulus .  Consequently, all species with pale-spotted or -striped upper parts are known as "chevrotain" and without are known as "mouse-deer".
The Telugu name for the Indian spotted chevrotain is jarini pandi, which literally means "a deer and a pig".[ citation needed ] In Kannada, it is called barka (ಬರ್ಕ), in Malayalam, it is called കൂരമാൻkūramān, and the Konkani name for it is barinka. The Tamil term is சருகு மான்sarukumāṉ "leaf-pile deer". The Sinhala name meeminna roughly translates to "mouse-like deer". This was used in the scientific name of the Sri Lankan spotted chevrotain, M. meminna.
The family was widespread and successful from the Oligocene (34 million years ago) through the Miocene (about 5 million years ago), but has remained almost unchanged over that time and remains as an example of primitive ruminant form. They have four-chambered stomachs to ferment tough plant foods, but the third chamber is poorly developed. Though most species feed exclusively on plant material, the water chevrotain occasionally takes insects and crabs or scavenges meat and fish.  Like other ruminants, they lack upper incisors. They give birth to only a single young.
In other respects, however, they have primitive features, closer to nonruminants such as pigs. All species in the family lack antlers and horns, but both sexes have elongated canine teeth. These are especially prominent in males, where they project out on either side of the lower jaw, and are used in fights.  Their legs are short and thin, which leave them lacking in agility, but also helps to maintain a smaller profile to aid in running through the dense foliage of their environments. Other pig-like features include the presence of four toes on each foot, the absence of facial scent glands, premolars with sharp crowns,  and the form of their sexual behaviour and copulation.  
They are solitary or live in pairs.  The young are weaned at three months of age, and reach sexual maturity between 5 and 10 months, depending on species. Parental care is relatively limited. Although they lack the types of scent glands found in most other ruminants, they do possess a chin gland for marking each other as mates or antagonists, and, in the case of the water chevrotain, anal and preputial glands for marking territory. Their territories are relatively small, on the order of 13–24 hectares (32–59 acres), but neighbors generally ignore each other, rather than compete aggressively. 
Some of the species show a remarkable affinity with water, often remaining submerged for prolonged periods to evade predators or other unwelcome intrusions. This has also lent support to the idea that whales evolved from water-loving creatures that looked like small deer.  
Tragulidae's placement within Artiodactyla can be represented in the following cladogram:     
Traditionally, only four extant species were recognized in the family Tragulidae.  In 2004, T. nigricans and T. versicolor were split from T. napu, and T. kanchil and T. williamsoni were split from T. javanicus.  In 2005, M. indica and M. kathygre were split from M. meminna.  With these changes, the 10 extant species are:
The Hypertragulidae were closely related to the Tragulidae.
The six extinct chevrotain genera  include:
The extinct chevrotains might also include  
Ungulates are members of the diverse clade Ungulata which primarily consists of large mammals with hooves. Living ungulates are divided into two orders: the odd-toed ungulates (Perissodactyla) including horses, rhinoceroses, and tapirs; and even-toed ungulates (Artiodactyla) such as cattle, pigs, giraffes, camels, sheep, deer, and hippopotamuses. Cetaceans such as whales, dolphins, and porpoises are also classified as even-toed ungulates, 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, native to South America, became extinct at the end of the Pleistocene, around 12,000 years ago.
Ruminants are hoofed herbivorous grazing or browsing mammals that are able to acquire nutrients from plant-based food by fermenting it in a specialized stomach prior to digestion, principally through microbial actions. The process, which takes place in the front part of the digestive system and therefore is called foregut fermentation, typically requires the fermented ingesta to be regurgitated and chewed again. The process of rechewing the cud to further break down plant matter and stimulate digestion is called rumination. The word "ruminant" comes from the Latin ruminare, which means "to chew over again".
The water chevrotain, also known as the fanged deer, is a small ruminant found in tropical Africa. This is the only species in the genus Hyemoschus. It is the largest of the 10 species of chevrotains, basal even-toed ungulates which are similar to deer, but are barely larger than small dogs.
Pecora is an infraorder of even-toed hoofed mammals with ruminant digestion. Most members of Pecora have cranial appendages projecting from their frontal bones; only two extant genera lack them, Hydropotes and Moschus. The name “Pecora” comes from the Latin word pecus, which means “horned livestock”. Although most pecorans have cranial appendages, only some of these are properly called “horns”, and many scientists agree that these appendages did not arise from a common ancestor, but instead evolved independently on at least two occasions. Likewise, while Pecora as a group is supported by both molecular and morphological studies, morphological support for interrelationships between pecoran families is disputed.
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 true deer family (Cervidae), but is rather more closely connected to antelope and antelope-like bovids; it is a member of the chevrotain family, a grouping of some of the world's smallest hoofed mammals.
The Cetruminantia are a clade made up of the Cetancodontamorpha and their closest living relatives, the Ruminantia.
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.
Tragulus is a genus of even-toed ungulates in the family Tragulidae that are known as mouse-deer. In Ancient Greek τράγος (tragos) means a male goat, while the Latin diminutive –ulus means 'tiny'. With a weight of 0.7–8.0 kg (1.5–17.6 lb) and a length of 40–75 cm (16–30 in), they are the smallest ungulates in the world, though the largest species of mouse-deer surpass some species of Neotragus antelopes in size. The mouse-deer are restricted to Southeast Asia from far southern China to the Philippines (Balabac) and Java.
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.
The Indian spotted chevrotain is a species of even-toed ungulate in the family Tragulidae. It is native to India and possibly Nepal. It lives in rainforests and is nocturnal. It has a body length of 57.5 cm (22.6 in) with a 2.5 cm (0.98 in) long tail length and weighs around 3 kg (6.6 lb). This was earlier included under the name of Tragulus meminna, but studies on the systematics of the group have led to that name being restricted to the Sri Lankan spotted chevrotain.
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.
Moschiola meminna is a species of even-toed ungulate in the chevrotain family (Tragulidae). Particularly in the old literature, M. meminna often refers to the spotted chevrotains as a whole. Today, the name is increasingly restricted to the Sri Lankan spotted chevrotain or white-spotted chevrotain, with the Indian spotted chevrotain M. indica and/or the yellow-striped chevrotain M. kathygre treated as distinct species.
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.
Artiofabula is a clade made up of the Suina and the Cetruminantia. The clade was found in molecular phylogenetic analyses and contradicted traditional relationships based on morphological analyses.
Tragulina is an infraorder of even-toed ungulates. Only the chevrotains survive to the present, including the genera Tragulus and Hyemoschus, all within the family Tragulidae.
Afrotragulus is an extinct genus of tragulid ruminant which existed in Kenya during the early Miocene period. It contains the species Afrotragulus moruorotensis and Afrotragulus parvus, formerly classified in genus Dorcatherium, as well as A. akhtari, A. megalomilos, and A. moralesi.