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==Taxonomy==
The Java mouse-deer’sdeer's common scientific name is ''Tragulus javanicus'', although other classification names for it exist, including ''Tragulus javanica'', ''Cervus javanicus'', and the [[heterotypic synonym]] ''Tragulus fuscatus''.<ref name=iucn /><ref name=meijaard>{{cite journal | last1 = Meijaard | first1 = I. | last2 = Groves | first2 = C. P. | year = 2004 | title = A taxonomic revision of the Tragulus mouse-deer. | url = | journal = Zoological Journal of the Linnean Society | volume = 140 | issue = | pages = 63–102 | doi=10.1111/j.1096-3642.2004.00091.x}}</ref><ref name=ARKive4>Javan mouse-deer (Tragulus javanicus). (2013). ARKive - Discover the world's most endangered species. Retrieved from http://www.arkive.org/javan-mouse-deer/tragulus-javanicus</ref><ref>Facts about Lesser Mouse Deer (Tragulus javanicus) - Encyclopedia of Life. (n.d.). Encyclopedia of Life - Animals - Plants - Pictures & Information. Retrieved from http://eol.org/pages/328339/names/synonyms</ref> The Java mouse-deer is also known by many common names, including Javan chevrotain, Javan mousdeer, or Java Mousedeer.<ref name=eof5>Facts about Lesser Mouse Deer (Tragulus javanicus) - Encyclopedia of Life. (n.d.). Encyclopedia of Life - Animals - Plants - Pictures & Information. Retrieved from http://eol.org/pages/328339/</ref> The taxonomic status of the Java mouse-deer is questionable, but recent craniometric analyses have begun to shed light on the taxonomic discrepancies. Previously, the Java mouse-deer, ''Tragulus javanicus'', was commonly thought to represent the wider class of large [[chevrotain]]s, but it was found that these, unlike the Java mouse-deer, do not likely reside on [[Java]]. Three species groups of ''Tragulus'' have been identified based on craniometric skull analyses and coat coloration patterns. These three species groups are ''Tragulus javanicus'', ''[[Tragulus napu]]'', and ''[[Tragulus versicolor]]''. Based upon these craniometric analyses, ''Tragulus javanicus'' was then further separated based on the organisms’ known geographic locations: ''[[Tragulus williamsoni]]'' (found in northern Thailand and possibly southern China), ''[[Tragulus kanchil]]'' (found in Borneo, Sumatra, the Thai–Malay Peninsula, islands within the Greater Sunda region, and continental Southeast Asia), and ''Tragulus javanicus'' (found in Java).<ref name=meijaard6>{{cite journal | last1 = Meijaard | first1 = E. | last2 = Groves | first2 = C. P. | year = 2004 | title = A Taxonomic Revision Of The Tragulus Mouse-deer (Artiodactyla) | url = http://onlinelibrary.wiley.com/doi/10.1111/j.1096-3642.2004.00091.x/abstract | journal = Zoological Journal of the Linnean Society | volume = 140 | issue = 1| pages = 63–102 | doi=10.1111/j.1096-3642.2004.00091.x}}</ref> Thus, because of its uniqueness to the island of Java, the Java mouse-deer is now considered a distinct species, although this fact has not significantly affected its current classification.<ref name=redorbit7>Java Mouse Deer, ''Tragulus javanicus'' - Mammals Reference Library - redOrbit. (n.d.). redOrbit - Science, Space, Technology, Health News and Information. Retrieved from http://www.redorbit.com/education/reference_library/science_1/mammalia/1112721404/java-mouse-deer-tragulus-javanicus/</ref>
==Appearance and biology==
Mouse-deer possess a triangular-shaped head, arched back, and round body with elevated rear quarters. The thin, short legs which support the mouse-deer are about the diameter of an average pencil. Although Java mouse-deer do not possess antlers or horns like regular deer, male Java mouse-deer have elongated, tusk-like upper canines which protrude downward from the upper jaw along the sides of their mouth. Males use these “tusks” to defend themselves and their mates against rivals.<ref name=superhero8>Nowak, R., J. Paradiso. 1983. Walker's Mammals of the World. Chicago: Johns Hopkins University Press.</ref> Females can be distinguished from males because they lack these prominent canines, and they are slightly smaller than the males.<ref name=eof5/> Java mouse-deer can furthermore be distinguished by their lack of upper incisors. The coat coloration of the Java mouse-deer is reddish-brown with a white underside. Pale white spots or vertical markings are also present on the animal’sanimal's neck.<ref name=eof5/>
With an average length of {{Convert|45|cm|abbr=on}} and an average height of {{Convert|30|cm|abbr=on}}, the Java mouse-deer is the smallest [[Neontology|extant]] (living) ungulate or hoofed mammal, as well as the smallest extant even-toed ungulate.<ref name=eof5/><ref name=erythrocytes9>{{cite journal|last1=Fukuta|first1=K.|last2=Kudo|first2=H|last3=Jalaludin|first3=S.|year=1996|title=Unique pits on the erythrocytes of the lesser mouse-deer, Tragulus javanicus|journal=Journal of Anatomy|volume=189|issue=1|pages=211–213|pmc=1167845|pmid=8771414}}</ref><ref name=JoB/> The weight of the Java mouse-deer ranges from {{Convert|1|to|2|kg}}, with males being heavier than females. It has an average tail length of about {{Convert|5|cm|abbr=on}}. Mouse-deer are thought to be the most primitive [[ruminant]]s based on their behaviour and the [[fossil]] record, thus they are the living link between ruminants and non-ruminants.<ref name=animalrecs10>Carwardine, M., & London, E. (2007). Animal records. New York: Sterling</ref><ref name=JoB>{{Cite journal|last=Matsubayashi|first=Hisashi|last2=Bosi|first2=Edwin|last3=Kohshima|first3=Shiro|date=28 February 2003|title=Activity and Habitat Use of Lesser Mouse-Deer (Tragalus javanicus)|url=https://academic.oup.com/jmammal/article/84/1/234/2373235|journal=Journal of Mammalogy|language=en|volume=84|issue=1|pages=234–242|doi=10.1644/1545-1542(2003)084<0234:AAHUOL>2.0.CO;2|issn=0022-2372}}</ref>
The Java mouse-deer is [[endotherm|endothermic]]ic and [[homoeothermic]], and has an average basal metabolic rate of about 4.883 [[watt]]s.<ref name=eof5/> It also has the smallest [[red blood cell]]s (erythrocytes) of any mammal, and about 12.8% of the cells have pits on them. The pits range in diameter from 68 to 390 [[nanometre]]s. Red blood cells with pits are unique and have not been reported before either physiologically or pathologically.<ref name=erythrocytes9/>
==Ecology==
==Reproduction==
Java mouse-deer are capable of breeding at any time during the year, and this has been observed during captivity.<ref name=eof5/><ref name=adw12 /> However, some sources have observed that the breeding season for the Java mouse-deer in nature occurs from November to December.<ref name=hayssen15>Hayssen, V., & Tienhoven, A. v. (1993). Asdell's patterns of mammalian reproduction: a compendium of species-specific data. Ithaca: Cornell University Press</ref> Additionally, female mouse-deer have the potential to be pregnant throughout most of their adult life, and they are capable of conceiving 85–155 minutes after giving birth.<ref name=adw12/> The Java mouse-deer’sdeer's gestation period usually lasts 4.5 months, or 144 days.<ref name=eof5/><ref name=adw12 /> Typical litters consist of a single fawn, which resembles a miniature adult, although the tusk-like incisors prevalent in males are not visible in the young mouse-deer.<ref name=eof5/> The average mass of a newborn fawn is {{Convert|370|g}}, and these precocial young are capable of standing within 30 minutes after birth. Fawns are capable of eating solid food within two weeks, yet it takes around 12 weeks to completely wean the fawns.<ref name=superhero8/> On average, it takes the young, both male and female, 167 days (~5 months) to reach sexual maturity.<ref name=kingdon16>Kingdon, J. (1989). East African mammals : an atlas of evolution in Africa. London: Academic Press</ref> Mouse-deer have been observed to live up to 14 years in captivity, but their lifespan in nature is still an open question.<ref name=eof5/>
==Predators==
==Conservation status==
Java mouse-deer is currently categorized as “Data Deficient” on the International Union for Conservation of Nature’sNature's [[Red List]].<ref name=iucn /> This data deficiency is due to the inconclusiveness regarding the distinct separation of ''Tragulus'' species, in addition to the lack of information on ''Tragulus javanicus''. Even comparison of past observed numbers of Java mouse-deer with those presently observed does not greatly aid researchers because of the high likelihood of inaccuracy in past observations. Although listed as “Data Deficient,” it is highly probable that a decline in the numbers of Java mouse-deer is occurring, and upon further investigation of this issue, the Red List status of ''Tragulus javanicus'' could easily change to “Vulnerable”.<ref name=iucn /> Some conservation actions which have been implemented include legally protecting the species, which, although it has been in effect since 1931, makes no significant difference since hunting of Java mouse-deer still occurs.{{Citation needed|date = June 2015}} Additionally, some areas of Java which the Java mouse-deer frequents have been protected, yet enforcement of these regulations is still needed. One of the greatest conservation efforts needed is simply more information about the species: a more complete definition of its taxonomy, as well as more information on its habitat and behavior.
==Indonesian folklore==
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