''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" 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
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 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 Chattian ...
about 34 million years ago. This species, ''
Ptilocercus kylin'', 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