MONKEYS

Monkey is a common name that may refer to most mammals of the infraorder Simiiformes,also known as the simians. Traditionally, all animals in the group now known as simians are counted as monkeys except the apes, a grouping known as paraphyletic,however in the broader sense based on cladistics, apes (Hominoidea) are also include, making the terms monkeys and simians synonyms in regard of their scope.Monkeys are divided into the families of New World monkeys (Platyrrhini) and Old World monkeys (Cercopithecidea in the strict sense, Catarrhini in the broad sense which again includes apes).

Simians and tarsiers, the two members of the suborder Haplorhini, emerged some 60 million years ago. Old World monkeys and apes emerge within the catarrhine monkeys some 25 million years ago. Extinct basal simians such as Aegytopithecus or Parapithecus [35-32 million years ago] are also considered monkeys by primatologists. Lemurs, lorises, and galagos are not monkeys, instead they are strepsirrhine primates (suborder Strepirrhini) The simians' sister group, the tarsiers are also haplorhine primates, however, they are also not monkeys.

Apes emerged within "monkys" as sisters of the Cercopithecidea in the Catarrhini, so cladistically they are monkeys as well.There has been resistance to directly designate apes (and thus humans)as monkeys, so "Old World monkey" may be taken to mean either the Cercopithecoidea (not including apes) or the Catarrhini (including apes. That apes are monkeys was realized by Georges-Louis Leclerc, Comte de Button in the 18th century. monkeys, including apes can be distinguished from other primates by having only two pectoral nipples, a pendulous penis, and a lack of sensory.