''Ptilocercus'' is a genus of

treeshrew The treeshrews (or tree shrews or banxrings) are small mammals native to the tropical forests of South and Southeast Asia. They make up the entire order Scandentia, which split into two families: the Tupaiidae (19 species, "ordinary" treeshrews) ...

and the sole member of the family Ptilocercidae.

Taxonomy

Today the genus (and family) is represented by a single species, the

pen-tailed treeshrew The pen-tailed treeshrew (''Ptilocercus lowii'') is a treeshrew of the family Ptilocercidae native to southern Thailand, the Malay Peninsula, Borneo, and some Indonesian islands. It is the only living species in the genus ''Ptilocercus''. All ...

''(Ptilocercus lowii)''. However, this genus is very ancient and considered the most primitive of all the treeshrews. In 2016 a new species was described from

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

dated to the

Early Oligocene The Rupelian is, in the geologic timescale, the older of two ages or the lower of two stages of the Oligocene Epoch/Series. It spans the time between . It is preceded by the Priabonian Stage (part of the Eocene) and is followed by the Chatti ...

about 34 million years ago. This species, ''

Ptilocercus kylin ''Ptilocercus'' is a genus of treeshrew and the sole member of the family Ptilocercidae. Taxonomy Today the genus (and family) is represented by a single species, the pen-tailed treeshrew ''(Ptilocercus lowii)''. However, this genus is very anc ...

'', is so strikingly similar to the living species that it can be considered a

sister taxa In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

. This suggests that the Ptilocercidae have evolved little change over millions of years.

References

Mammal genera Mammal genera with one living species Taxa named by John Edward Gray Treeshrews {{Mammal-stub