The term lemur is generically used for the members of the four lemuriform families: Cheirogaleidae, Lemuridae, Lepilemuridae, and Indriidae.
The term also is used in a more restrictive sense to refer only to the members of the family Lemuridae.
Lemurs are endemic (found naturally) only on the island of Madagascar and some smaller surrounding islands, including the Comoros (where it is likely they were introduced by humans).
Lemurs have opposable thumbs and long grasping toes, but their tails are not prehensile.
The two so-called flying lemur species are not lemurs, nor are they even primates.
All lemur species have a tapetum, the reflective layer over the retina (Strier 2000).
Within the Strepsirrhini there are different infraorders, one of which is the infraorder Lemuriformes, the lemurs.
Lemurs have nails rather than claws on their fingers and toes; these nails are flat with the exception of the stout, clawlike nail on the second toes of the feet.
The remainder of the lemurs, the lemuroids (superfamily Lemuroidea) are primarily herbivores, although some species supplement their diet with insects.
Lemurs depend quite heavily on the sense of smell and have large nasal cavities and moist noses (Strier).
All lemurs are endangered species or threatened species and many species of lemur became extinct in recent centuries, due mainly to habitat destruction (deforestation) and hunting.
Lemurs are native to Madagascar and adjacent islands.
The Cheirogaleidae have a pedal structure, similar to the other strepsirrhine families and the haplorrhines, suggesting they split off from the other lemurs first.
Lemurs are thought to have limited color vision (Strier).
The term "lemur" is derived from the Latin word lemures, meaning "spirits of the night," or "ghost(s)" and likely refers to the large, reflective eyes that many of the nocturnal lemur species have.