Prosimians are the suborder Strepsirhini, the most primitive extant primates; they represent forms that were ancestral to monkeys, apes and man. Prosimians are the only primates native to Madagascar, and are also found in Southeast Asia. The tarsiers are also considered prosimians, though they are not strepsirhines.

The Strepsirhini clade is composed of seven families split into two groups. The first group contains the four families of creatures typically called lemurs. The other three families include all of the lorises, plus the galagos, the Aye-aye, and the pottos. Because they are prosimians, the tarsiers were once classified in the Strepsirhini; they are now grouped in suborder Haplorhini with the monkeys and apes and are the most primitive of the extant haplorhines.

The adapids are an extinct polyphyletic grouping that were most certainly prosimians and closely related to the strepsirhines. The omomyids are another extinct group of prosmians but they are believed to be more closely related to the tarsiers.

• ORDER PRIMATES
  • Suborder Strepsirhini: non-tarsier prosimians
    • Family Cheirogaleidae: dwarf and mouse lemurs
    • Family Lemuridae: lemurs
    • Family Megaladapidae: sportive lemurs
    • Family Indriidae: wooly lemurs and allies
    • Family Daubentoniidae: Aye-aye
    • Family Loridae: lorises, pottos and allies
    • Family Galagonidae: galagos
  • Suborder Haplorhini: tarsiers, monkeys and apes