Squirrel monkey

Squirrel monkeys are New World monkeys of the genus Saimiri. Saimiri is the only genus in the subfamily Saimirinae. The name of the genus is of Tupi origin (sai-mirim or gai-mbirin < sai 'monkey' and mirim 'small') and was also used as an English name by early researchers. Squirrel monkeys live in the tropical forests of Central and South America in the canopy layer. Most species have parapatric or allopatric ranges in the Amazon, while S. oerstedii is found disjunctly in Costa Rica and Panama. The common squirrel monkey is captured for the pet trade and for medical research but it is not threatened. Two squirrel monkey species are threatened: the Central American squirrel monkey and the black squirrel monkey are listed as vulnerable by the IUCN. Until 1984, all South American squirrel monkeys were considered part of a single widespread species, and many zoologists considered the Central American squirrel monkey to be a member of that single species as well. The two main groups currently recognized can be separated by the white above the eyes; it is shaped as a Gothic ('pointed') arch in the S. sciureus group, while it is shaped as a Roman ('rounded') arch in the S. boliviensis group. Mammal Species of the World (2005) recognized the following 5 species: Subsequent taxonomic research has recognized Saimiri sciureus cassiquiarensis as a separate species Saimiri cassiquiarensis, and also recognized an additional species, Collins' squirrel monkey Saimiri collinsi that had previously been considered to be within S. sciureus. Some more recent taxonomies also recognize Saimiri sciureus macrodon as a separate species Saimiri macrodon, but others recognize S. macrodon to be a synonym of Saimiri cassiquiarensis. The crown lineage of the extant squirrel monkeys appears to have diverged around 1.5 million years ago. S. boliviensis appears to be the first diverging species in the group. S. oerstedii and S. s. sciureus, are sister species. S. s. macrodon is the sister species to the S. oerstedii / S. s. sciureus clade. Squirrel monkey fur is short and close, coloured black at the shoulders and yellowish orange on its back and extremities. The upper parts of their heads are hairy. This black-and-white face gives them the name 'death's head monkey' in several Germanic languages (e.g., German Totenkopfaffen, Swedish dödskalleapor, Dutch doodshoofdaapjes) and Slovenian (smrtoglavka). Squirrel monkeys grow from 25 to 35 centimetres (9.8 to 13.8 in) long, plus a 35 to 42 centimetres (14 to 17 in) tail. Male squirrel monkeys weigh 750 to 1,100 grams (26 to 39 oz). Females weigh 500 to 750 grams (18 to 26 oz). Both males and females are equipped with long and hairy tails, flat nails, and pointed claws.