Colugo

Colugos[1]
Temporal range:
Eocene-Holocene, 37–0 Ma
Sunda flying lemur
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Mirorder: Primatomorpha
Order: Dermoptera
Illiger, 1811
Family: Cynocephalidae
Simpson, 1945
Type genus
Cynocephalus
Genera

Colugos (/kəˈluːɡoʊz/[2][3]) are arboreal gliding mammals found in Southeast Asia. Just two extant species[1] make up the entire family Cynocephalidae (/ˌsaɪnoʊˌsɛfəˈlaɪdiː, -ˌkɛ-/[4]) and order Dermoptera. They are the most capable gliders of all gliding mammals, using flaps of extra skin between their legs to glide from higher to lower locations. They are also known as cobegos or flying lemurs, though they are not true lemurs.

Characteristics

Colugos are fairly large for a tree-dwelling mammal: at about 35 to 40 cm (14 to 16 in) in length and 1 to 2 kg (2.2 to 4.4 lb) in weight, they are comparable to a medium-sized possum or a very large squirrel.[5] They have moderately long, slender limbs of equal length front and rear, a medium-length tail, and a relatively light build. The head is small, with large, front-focused eyes for excellent binocular vision, and small, rounded ears. When born, a colugo weighs only about 35 g (1.2 oz) and does not reach adult size for 2–3 yr.[6]

Their most distinctive feature is the membrane of skin that extends between their limbs and gives them the ability to glide long distances between trees. Of all the gliding mammals, the colugos have the most extensive adaptation to flight. Their gliding membrane, or patagium, is as large as is geometrically possible: it runs from the shoulder blades to the fore paw, from the tip of the rear-most finger to the tip of the toes, and from the hind legs to the tip of the tail;[7] unlike in other known gliding mammals, even the spaces between the fingers and toes are webbed to increase the total surface area, as in the wings of bats. As a result, colugos were traditionally considered being close to the ancestors of bats, but are now seen by some as the closest living relatives to primates.[8]

Lower jaw (Galeopterus)

They are surprisingly clumsy climbers. Lacking opposable thumbs and not being especially strong, they proceed upwards in a series of slow hops, gripping onto the bark of trees with their small, sharp claws. They are as comfortable hanging underneath a branch as sitting on top of it. In the air, however, they are very capable, and can glide as far as 70 m (230 ft) from one tree to another with minimal loss of height.[9]

Colugos are shy, nocturnal, and restricted to the tropical rainforests of Southeast Asia. In consequence, remarkably little is known about their habits, although they are believed to be generally solitary, except for mothers nursing young. They are certainly herbivores, and are thought to eat mostly leaves, shoots, flowers, and sap, and probably fruit, as well. They have well-developed stomachs and long intestines, capable of extracting nutriment from leaves.

The incisor teeth of colugos are highly distinctive; they are comb-like in shape, with up to 20 tines on each tooth. The comb-like appearance is analogous in appearance and function to the incisor suite in strepsirhine primates that use these teeth for grooming. The second upper incisors have two roots, another unique feature among mammals. [7] The dental formula of colugos is: 2.1.2.33.1.2.3

Although they are placental mammals, colugos are marsupial-like in their breeding habits. The young are born after 60 days of gestation in a tiny and undeveloped form, and spend their first six months or so of life clinging to the mother's belly. To protect them and transport them, she curls her tail up to fold the gliding membrane into a warm, secure quasi pouch. Breeding is fairly slow, as the young do not reach full size until they are two or three years old.[7]

Status

Both species are threatened by habitat destruction, and the Philippine flying lemur was classified by the IUCN as vulnerable at one time. The IUCN 1996 had declared the species vulnerable due to destruction of lowland forests and hunting. It was downlisted to least concerns in 2008, but still under the same threats as before. In addition to the ongoing clearing of its rainforest habitat, it is hunted for its meat and fur. It is also hunted by the gravely endangered Philippine eagle: some studies suggest colugos account for 90% of the eagle's diet. It is not known how the diurnal eagles catch so many of the nocturnal colugos, which are thought to spend the greater part of the day curled up in tree hollows or hanging inconspicuously underneath a branch.

Classification and evolution

The Mixodectidae appear to be fossil Dermoptera. Although other Paleogene mammals have been interpreted as related to dermopterans, the evidence for this association is uncertain and many of the fossils are no longer interpreted as being gliding mammals. At present, the fossil record of definitive dermopterans is limited to two species of the Eocene and Oligocene cynocephalid genus Dermotherium.[10]

Recent molecular phylogenetic studies have demonstrated that colugos belong to the clade Euarchonta along with the treeshrews (order Scandentia) and the primates, with the colugos more closely related to primates. In this taxonomy, the Euarchonta are sister to the Glires (lagomorphs and rodents), and the two groups are combined into the clade Euarchontoglires.[8]

Euarchontoglires
Glires

Rodentia (rodents)

Lagomorpha (rabbits, hares, pikas)



Euarchonta

Scandentia (treeshrews)


Primatomorpha

Dermoptera (colugos)

†Plesiadapiformes

Primates






Synonyms

The names Colugidae, Galeopithecidae, and Galeopteridae are synonyms for Cynocephalidae. Colugo, Dermopterus, Galeolemur, Galeopithecus, Galeopus, and Pleuropterus are synonyms for Cynocephalus.

References

  1. 1 2 Stafford, B.J. (2005). "Order Dermoptera". In Wilson, D.E.; Reeder, D.M. Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. p. 110. ISBN 978-0-8018-8221-0. OCLC 62265494.
  2. ↑ "Colugo". OxfordDictionaries.com. OUP. Retrieved 2016-01-21.
  3. ↑ "Colugo". Merriam-Webster Dictionary. Retrieved 2016-01-21.
  4. ↑ Cf. words with analogous pronunciations such as Meningoencephalitis, see "Meningoencephalitis". OxfordDictionaries.com. OUP. Retrieved 2016-01-21.
  5. ↑ Lim, Norman (2007). Colugo: The flying lemur of South-East Asia. Singapore: Draco Publishing and Distribution Pte Ltd.
  6. ↑ Macdonald (Ed), David W. (2006). The Encyclopedia of Mammals. Oxford University Press. ISBN 0-19-920608-2.
  7. 1 2 3 MacKinnon, Kathy (1984). Macdonald, D., ed. The Encyclopedia of Mammals. New York: Facts on File. pp. 446–447. ISBN 0-87196-871-1.
  8. 1 2 Jan E. Janecka, Webb Miller, Thomas H. Pringle, Frank Wiens, Annette Zitzmann, Kristofer M. Helgen, Mark S. Springer, William J. Murphy (2007). "Molecular and Genomic Data Identify the Closest Living Relative of Primates". Science 318 (5851): 792–794. Bibcode:2007Sci...318..792J. doi:10.1126/science.1147555. PMID 17975064.
  9. ↑ Dawkins, Richard (2004). The Ancestor's Tale. Phoenix. ISBN 978-0-7538-1996-8.
  10. ↑ Marivaux, L., L. Bocat, Y. Chaimanee, J.-J. Jaeger, B. Marandat, P. Srisuk, P. Tafforeau, C. Yamee, and J.-L. Welcomme (2006). "Cynocephalid dermopterans from the Palaeogene of South Asia (Thailand, Myanmar and Pakistan): systematic, evolutionary and palaeobiogeographic implications". Zoologica Scripta 35 (4): 395–420. doi:10.1111/j.1463-6409.2006.00235.x.

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