''Eupetaurus'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

rodent Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are n ...

in the family

Sciuridae Squirrels are members of the family Sciuridae, a family that includes small or medium-size rodents. The squirrel family includes tree squirrels, ground squirrels (including chipmunks and prairie dogs, among others), and flying squirrels. Squ ...

. Members of this genus are known as woolly flying squirrels. They are large to very large flying squirrels found in the highest rocky cliffs near the

treeline The tree line is the edge of the habitat at which trees are capable of growing. It is found at high elevations and high latitudes. Beyond the tree line, trees cannot tolerate the environmental conditions (usually cold temperatures, extreme snowp ...

of the

Himalayas The Himalayas, or Himalaya (; ; ), is a mountain range in Asia, separating the plains of the Indian subcontinent from the Tibetan Plateau. The range has some of the planet's highest peaks, including the very highest, Mount Everest. Over 10 ...

and

Tibetan Plateau The Tibetan Plateau (, also known as the Qinghai–Tibet Plateau or the Qing–Zang Plateau () or as the Himalayan Plateau in India, is a vast elevated plateau located at the intersection of Central, South and East Asia covering most of the ...

. Due to the inaccessibility of their montane habitat, they are difficult to study.

Taxonomy

Flying squirrels in the central and eastern Himalayas have been separated from those in the western Himalayas by the

Ganges The Ganges ( ) (in India: Ganga ( ); in Bangladesh: Padma ( )). "The Ganges Basin, known in India as the Ganga and in Bangladesh as the Padma, is an international river to which India, Bangladesh, Nepal and China are the riparian states." is ...

and Yarlung Tsangpo rivers, and are thought to have diverged in the Neogene, between 4.5 to 10.2 million years ago.

Species

For more than a century since its description by Oldfield Thomas, the only species in the genus was thought to be the western woolly flying squirrel (''E. cinereus''), which is found in northern

Pakistan Pakistan ( ur, ), officially the Islamic Republic of Pakistan ( ur, , label=none), is a country in South Asia. It is the world's fifth-most populous country, with a population of almost 243 million people, and has the world's second-lar ...

and northwestern

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

. However, an analysis of museum specimens found evidence of two more species in the eastern Himalayas, the Tibetan woolly flying squirrel (''E. tibetensis'') and the Yunnan woolly flying squirrel (''E. nivamons''). There are currently three known species in the genus: * Western woolly flying squirrel (''Eupetaurus cinereus'') * Tibetan woolly flying squirrel (''Eupetaurus tibetensis'') * Yunnan woolly flying squirrel (''Eupetaurus nivamons'')

Description

The cheek teeth are unique as they are both flat-crowned and high crowned (hypsodont), setting ''Eupetaurus'' apart from other squirrels and suggesting that they feed on very abrasive plant material, including pine needles.Zahler and Khan, 2003 The western woolly flying squirrel has a grizzled-grey pelage with pronounced frosting, in contrast to the more saturated brown coloration of the two other species, and has more robust cusps and cheek teeth.

Relationships

The woolly flying squirrels are unique among the flying squirrels because of their large size and unique dentition. This led a few early researchers to go so far as to create a distinct family. Some of their arguments were based on poorly drawn and labeled diagrams of the cranium and

lower jaw In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

of ''E. cinereus''. Zahler and Woods (1997) suggest instead that ''Eupetaurus'' is closely related to another genus of large flying squirrels, '' Petaurista''. A 2021 study suggested that ''Eupetaurus'' is the sister genus to a clade consisting of '' Aeromys'' and '' Biswamayopterus''.

References

{{Taxonbar, from=Q10759605 Eupetaurus Taxa named by Oldfield Thomas Rodent genera