Chevrotains, also known as mouse-deer, are small ungulates that make up the family Tragulidae, the only members of the infraorder Tragulina. The 10 extant species are in three genera, but several species also are only known from fossils. The extant species are found in forests in South and Southeast Asia, with a single species in the rainforests of Central and West Africa. They are solitary or live in pairs, and feed almost exclusively on plant material. Depending on exact species, the Asian species weigh between 0.7 and 8.0 kilograms (1.5 and 18 lb), and the smallest species are also the smallest ungulates in the world. The African chevrotain is considerably larger at 7–16 kilograms (15–35 lb).
The word 'chevrotain' itself is French, and can be translated as 'little 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 upperparts are known as chevrotains, and all the species 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". In Kannada, it is called barka (ಬರ್ಕ), in Malayalam, it is called “khooran", and the Konkani name for it is barinka.
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 a four-chambered stomach 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, and 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 horns, but both genders 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 environment. 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 five and ten 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, 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 intrusion. This has also lent support to the idea that whales evolved from water-loving creatures that looked like small deer.
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 was split from T. javanicus. In 2005, M. indica and M. kathygre were split from M. meminna. With these changes, the 10 extant species are:
- SUBORDER Ruminantia
- Family Tragulidae
- Genus Hyemoschus
- Genus Moschiola
- Genus Tragulus
- Family Moschidae: musk deer
- Family Cervidae: deer
- Family Giraffidae: giraffe and okapi
- Family Antilocapridae: pronghorn
- Family Bovidae: cattle, goats, sheep, and antelope
- Family Tragulidae
The six extinct chevrotains genera include:
- Genus Dorcatherium
- Genus Dorcabune
- Genus Afrotragulus Sánchez, Quiralte, Morales and Pickford, 2010 
- Genus Siamotragulus
- Genus Yunnanotherium
- Genus Archaeotragulus
- Genus Krabitherium
- Wilson, D. E.; Reeder, D. M., eds. (2005). Mammal Species of the World (3rd ed.). Johns Hopkins University Press. ISBN 978-0-8018-8221-0. OCLC 62265494. http://www.bucknell.edu/msw3/browse.asp?id=14200123.
- Groves, C., and E. Meijaard (2005). Intraspecific variation in Moschiola, the Indian Chevrotain. The Raffles Bulletin of Zoology. Supplement 12: 413-421
- Farooq, U., Khan, M.A., Akhtar, M. and Khan, A.M. 2008. Lower dentition of Dorcatherium majus (Tragulidae, Mammalia) in the Lower and Middle Siwaliks (Miocene) of Pakistan. Tur. J. Zool., 32: 91-98. http://journals.tubitak.gov.tr/zoology/issues/zoo-08-32-1/zoo-32-1-14-0612-5.pdf
- Nowak, R. M. (eds) (1999). Walker's Mammals of the World. 6th edition. Johns Hopkins University Press.
- UltimateUngulate: Hyemoschus aquaticus. Accessed 12 October 2010.
- IUCN SSC Antelope Specialist Group (2008). Hyemoschus aquaticus. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on 12 October 2010..
- IUCN SSC Antelope Specialist Group (2008). Moschiola indica. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on 12 October 2010..
- IUCN SSC Antelope Specialist Group (2008). Moschiola kathygre. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on 12 October 2010..
- IUCN SSC Antelope Specialist Group (2008). Moschiola meminna. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on 12 October 2010..
- Kingdon, J. (1997). The Kingdon Field Guide to African Mammals. Academic Press. ISB 0-12-408355-2
- Dubost, G. (1984). Macdonald, D.. ed. The Encyclopedia of Mammals. New York: Facts on File. pp. 516–517. ISBN 0-87196-871-1.
- "Aquatic deer and ancient whales". BBC News. 2009-07-07. http://news.bbc.co.uk/earth/hi/earth_news/newsid_8137000/8137922.stm. Retrieved 2010-03-26.
- Meijaard, I., and C. P. Groves (2004). A taxonomic revision of the Tragulus mouse-deer. Zoological Journal of the Linnean Society 140: 63-102.
- E. Thenius 1950. Über die Sichtung und Bearbeitung der jungtertiären Säugetierreste aus dem Hausruck und Kobernaußerwald (O.Ö.) in Verh. Geol. B.-A. 51/2, pp 56
- Israel M. Sánchez; Victoria Quiralte; Jorge Morales; Martin Pickford (2010). "A new genus of tragulid ruminant from the early Miocene of Kenya". Acta Palaeontologica Polonica 55 (2): 177–187. doi:10.4202/app.2009.0087. http://www.app.pan.pl/archive/published/app55/app20090087.pdf.
- Métais, G., Chaimanee, Y., Jaeger, J.-J. & Ducrocq S. 2001. New remains of primitive ruminants from Thailand: evidence of the early evolution of the Ruminantia in Asia. Zoologica Scripta. 30, 231-248. http://www.thaiscience.info/Article%20for%20ThaiScience/Article/5/Ts-5%20new%20remains%20of%20primitive%20ruminants%20from%20thailand%20evidence%20of%20the%20early%20evolution%20of%20the%20ruminantia%20in%20asia.pdf
- Terry A. Vaughan,James M. Ryan,Nicholas J. Czaplewski. Mammalogy (5th ed.). ISBN 9780-7637-6299-5. http://books.google.com.vn/books?id=LD1nDlzXYicC&pg=PA347&lpg=PA347&dq=Krabitherium&source=bl&ots=fyJgWhXyc-&sig=50YUsWHSv77nucYQ1h77STR7R-E&hl=vi&sa=X&ei=FR58T-eIFoGiiAeym4CeCQ&ved=0CFoQ6AEwBDgK#v=onepage&q=Krabitherium&f=false. Retrieved April 4, 2012.