Squirrels are members of the family Sciuridae, a family that includes small or medium-sized rodents. The squirrel family includes tree squirrels, ground squirrels, and flying squirrels. Squirrels are indigenous to the Americas, Eurasia, and Africa, and were introduced by humans to Australia. The earliest known fossilized squirrels date from the Eocene epoch, and among other living rodent families, the squirrels are most closely related to the mountain beaver and dormice.
Sciurinae is a subfamily of squirrels, uniting the flying squirrels with certain related tree squirrels. Older sources place the flying squirrels in a separate subfamily (Pteromyinae) and unite all remaining sciurids into the subfamily Sciurinae, but this has been strongly refuted by genetic studies.
The Neotropical pygmy squirrel is a South American species of tree squirrel, being the only living species in the genus Sciurillus and the subfamily Sciurillinae. Genetic analysis has shown it to be the sister group to all other squirrels.
The Philippine pygmy squirrel is a species of rodent in the family Sciuridae. It is endemic to the Philippines.
The least pygmy squirrel, also known as the plain pygmy squirrel, is a species of rodent in the family Sciuridae. This plain olive-brown squirrel is endemic to forests, mostly below an altitude of 750 m (2,500 ft) but locally significantly higher, on the Southeast Asian islands of Borneo, Sumatra and Banggi. Together with the African pygmy squirrel, the least pygmy squirrel is the smallest squirrel in the world, having a total length of 10–14 cm (3.9–5.5 in) and a weight of 12–26 g (0.42–0.92 oz).
The tufted pygmy squirrel is a species of rodent in the family Sciuridae. It is endemic to highland forest in Borneo. The common name of this tiny squirrel refers to its distinctive ear-tufts. Its diet consists mainly of the lichens and mosses which cover the trees it inhabits.
The sculptor squirrel or Bornean pygmy squirrel is a species of rodent in the family Sciuridae. It was described by Michael Rogers Oldfield Thomas in 1898. It is monotypic within the genus Glyphotes. It is endemic to northern Borneo in Sabah and Sarawak (Malaysia) and inhabits areas elevated at 285–1,800 metres (935–5,906 ft).
The Central American dwarf squirrel, also known as Alfaro's pygmy squirrel, is a small tree squirrel in the genus Microsciurus and tribe Sciurini found in Colombia, Costa Rica, Nicaragua, and Panama. No species of squirrel within this genus are listed as endangered, however they are rarely seen because they are extremely elusive. This suggests that their population numbers may be larger than documented.
The African pygmy squirrel is a species of rodent in the family Sciuridae. It is monotypic within the genus Myosciurus. It is found in tropical rainforests in Cameroon, the Republic of the Congo, Equatorial Guinea, and Gabon. It is not considered threatened, but likely declines locally due to habitat loss. Together with the least pygmy squirrel of Asia, the African pygmy squirrel is the world's smallest squirrel measuring about 12–14 cm (4.7–5.5 in) in total length and just 15–18 g (0.53–0.63 oz) in weight, which is less than a typical house mouse.
The black-eared squirrel is a species of rodent in the family Sciuridae. It is monotypic within the genus Nannosciurus. This tiny squirrel is found in forests in Borneo, Sumatra and Java. Except for its striking whitish and black facial markings, the black-eared squirrel resembles the least pygmy squirrel.
The Mindanao squirrel is a species of rodent in the family Sciuridae. It is endemic to the Philippines.
Swinhoe's striped squirrel is a small species of rodent in the family Sciuridae. This species is found mostly in China and Southeast Asia. Their diet consists of mostly seeds, fruits, nuts and ginger nectar. Like most squirrels they live in forest areas with mountains, usually in groups. They have litters that average in size of 3.25 offspring.
The Protoxerini comprise a tribe of squirrels found in Africa. The 30 species in six genera are:
The Callosciurinae are an Asiatic subfamily of squirrels containing over 60 species named after the genus Callosciurus, which means "beautiful squirrels".
Lawrence Richard Heaney is an American mammalogist, ecologist and biogeographer. His research focus is the mammals of the Philippines.
Callosciurini is a tribe of tree squirrels mainly found in southern Asia.
