Treeshrew

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Tree shrew
)

Treeshrews
Middle Eocene
– Recent
Tupaia
 sp.
CITES Appendix II (CITES)[2]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Grandorder: Euarchonta
Order: Scandentia
Wagner, 1855
Families
Red:
Ptilocercidae
The distribution and density of treeshrew species.

The treeshrews (also called tree shrews or banxrings

Ptilocercidae (one species, the pen-tailed treeshrew
).

Though called 'treeshrews', and despite having previously been classified in Insectivora, they are not true shrews, and not all species live in trees. They are omnivores; among other things, treeshrews eat fruit.

Treeshrews have a higher

brain to body mass ratio than any other mammal, including humans,[4]
but high ratios are not uncommon for animals weighing less than 1 kg (2 lb).

Among orders of mammals, treeshrews are closely related to

primates, and have been used as an alternative to primates in experimental studies of myopia, psychosocial stress, and hepatitis.[5]

Name

The name

Tupaia is derived from tupai, the Malay word for squirrel,[6] and was provided by Sir Stamford Raffles.[7]

Description

Dentition of Tupaia
Madras treeshrew (Anathana ellioti)
Northern smooth-tailed treeshrew (Dendrogale murina)
Northern treeshrew (Tupaia belangeri)
Common treeshrew (T. glis)
Horsfield's treeshrew (T. javanica)
Pygmy treeshrew (T. minor)
Pen-tailed treeshrew (1850 depiction of Ptilocercus lowii)

Treeshrews are slender animals with long tails and soft, greyish to reddish-brown fur. The terrestrial species tend to be larger than the arboreal forms, and to have larger claws, which they use for digging up insect prey. They have poorly developed canine teeth and unspecialised molars, with an overall dental formula of 2.1.3.33.1.3.3[8]

Treeshrews have good vision, which is binocular in the case of the more arboreal species.

Reproduction

Female treeshrews have a gestation period of 45–50 days and give birth to up to three young in nests lined with dry leaves inside tree hollows. The young are born blind and hairless, but are able to leave the nest after about a month. During this period, the mother provides relatively little maternal care, visiting her young only for a few minutes every other day to suckle them.

Treeshrews reach sexual maturity after around four months, and breed for much of the year, with no clear breeding season in most species.[8]

Behavior

Treeshrews live in small family groups, which defend their

nocturnal
.

They

mark their territories using various scent glands or urine
, depending on the particular species.

Diet

Treeshrews are omnivorous, feeding on insects, small vertebrates, fruit, and seeds. Among other things, treeshrews eat Rafflesia fruit.

The pen-tailed treeshrew in Malaysia is able to consume large amounts of naturally fermented nectar from flower buds of the bertam palm

Eugeissona tristis (with up to 3.8% alcohol content) the entire year without it having any effects on behaviour.[9][10]

Treeshrews have also been observed intentionally eating foods high in capsaicin, a behavior unique among mammals other than humans. A single TRPV1 mutation reduces their pain response to capsaicinoids, which scientists believe is an evolutionary adaptation to be able to consume spicy foods in their natural habitats.[11]

Taxonomy

They make up the entire

Ptilocercidae, the pen-tailed treeshrew. The 20 species are placed in five genera
.

Treeshrews were moved from the order

Primates because of certain internal similarities to primates (for example, similarities in the brain anatomy, highlighted by Sir Wilfrid Le Gros Clark), and classified as a "primitive prosimian", however they were soon split from the primates and moved into their own clade
. Taxonomists continue to refine the treeshrews' relations to primates and to other closely related clades.

superorder Euarchontoglires.[12] However, the alternative placement of treeshrews as sister to both Glires and Primatomorpha cannot be ruled out.[13] Some studies place Scandentia as sister of the Glires, which would invalidate Euarchonta: It is this organization that is shown in the tree diagram below.[14][13]

Euarchontoglires

Scandentia (treeshrews)

Glires

Lagomorpha (rabbits, hares, pikas)

Rodentia (rodents)

Primatomorpha

Several other arrangements of these orders have been proposed in the past, and the above tree is only a well-favored proposal.

short interspersed nuclear elements (SINEs) offer strong evidence for scandentia belonging to the euarchonta group:[19]

Euarchontoglires
Glires

Lagomorpha (rabbits, hares, pikas)

Rodentia (rodents)

Euarchonta

Scandentia (treeshrews)

Primatomorpha

Dermoptera (colugos)

Haplorrhini
)

Order Scandentia

Main article: List of scandentians

The 23 

Urogale was disbanded in 2011 when the Mindanao treeshrew was moved to Tupaia based on a molecular phylogeny.[20]

Family Tupaiidae
Family
Ptilocercidae

Fossil record

The fossil record of treeshrews is poor. The oldest putative treeshrew,

Middle Eocene of Henan, China, but the identity of this animal is uncertain. Other fossils have come from the Miocene of Thailand, Pakistan, India, and Yunnan, China, as well as the Pliocene of India. Most belong to the family Tupaiidae; one fossil species described from the Oligocene of Yunnan is thought to be closer to the pen-tailed treeshrew.[21]

Named fossil species include Prodendrogale yunnanica, Prodendrogale engesseri, and Tupaia storchi from Yunnan, Tupaia miocenica from Thailand, Palaeotupaia sivalicus from India[22] and Ptilocercus kylin from Yunnan.[21]

References

  1. OCLC 62265494
    .
  2. ^ "Appendices | CITES". cites.org. Retrieved 2022-01-14.
  3. ^ Rines, George Edwin, ed. (1920). "Tree-shrew" . Encyclopedia Americana.
  4. ^ "an article on Tupaia belangeri". The Genome Institute. Washington University. Archived from the original on 1 June 2010.
  5. S2CID 16910445
    . Retrieved 1 January 2012.
  6. ISBN 978-0-8018-5789-8
    .
  7. ^ Craig, John (1849). A new universal etymological technological, and pronouncing dictionary of the English Language.
  8. ^
    ISBN 978-0-87196-871-5
    .
  9. ^ Moscowicz, Clara (2008). "Tiny tree shrew can drink you under the table". NBC News.
  10. PMID 18663222.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  11. ^ "See Why Tree Shrews Are Only the Second Known Mammal to Seek Spicy Food". nationalgeographic.com. Archived from the original on August 27, 2018. Retrieved 2018-08-26.
  12. S2CID 12251814
    .
  13. ^
    PMID 25311886
    .
  14. S2CID 38120449
    .
  15. PMID 2575767
    .
  16. PMID 24333622
    .
  17. PMID 27325836
    .
  18. PMID 23560065
    .
  19. PMID 17307271
    .
  20. ^ a b Roberts, T.E.; Lanier, H.C.; Sargis, E.J.; Olson, L.E. (2011). "Molecular phylogeny of treeshrews (Mammalia: Scandentia) and the timescale of diversification in Southeast Asia". Molecular Phylogenetics and Evolution. 60 (3): 358–372.
    PMID 21565274
    .
  21. ^
    PMID 26766238
    .
  22. S2CID 85271080
    .
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