Prosimians are a type of primate that includes all living and extinct strepsirrhines (lemurs, lorisoids, and adapiforms), as well as the haplorhine tarsiers and their extinct relatives, the omomyiforms. They are considered to have characteristics that are more "primitive" (ancestral or plesiomorphic) than those of simians (monkeys, apes, and humans).

Prosimians are a type of primate that includes all living and extinct strepsirrhines (lemurs, lorisoids, and adapiforms), as well as the haplorhine tarsiers and their extinct relatives, the omomyiforms. They are considered to have characteristics that are more "primitive" (ancestral or plesiomorphic) than those of simians (monkeys, apes, and humans).