Monkeys are a diverse group of animals, ranging in size from the 3.5-ounce pygmy marmoset to the colorful mandrill, which can reach up to 82 pounds. To help understand the common traits and DNA links between the approximately 265 different species of monkeys, taxonomists have separated them into different sub-, infra-, and parvorders.
All monkeys are part of the Primate order. In addition to monkeys, this order includes humans, apes and prosimians. Primates generally have upright upper bodies, a natural tendency to walk on only two legs, and five fingers and toes on the hands and feet, including an opposable thumb. Some primates have prehensile tails, while others have no tails. This order of mammals is also known for having a high level of intelligence, but an inability to run, hear or see as well as many other animals.
Sub- and Infra-Orders
The Primate order contains two suborders: Strepsirrhini, which includes moist-nosed primates and is comprised mainly of lemurs; and Haplorrhini, or dry-nosed primates. Monkeys belong to the Haplorrhini suborder, along with humans and apes. Within Haplorrhini are two infra-orders, the Tarsiformes and the Simiformes. The Simiformes, formerly known as anthropoids, include the monkeys. Within the Simiformes infra-order, monkeys are further divided into two groups according to the part of the world in which they originated.
The Platyrrhini parvorder is one of the two divisions of Simiformes, and contains the species commonly referred to as New World monkeys. These are monkeys found in the Americas, mainly South American rain forests. This grouping includes the Callitricidae and Cebidae families. The Callitricidae family includes tamarins and marmosets, while well-known members of the Cebidae family include the squirrel, spider, howler, sakis, capuchin and titi monkeys. The marmosets and tamarins found within the New World grouping are among the smallest monkeys. These small monkeys are less likely to use their thumb to grip limbs and objects, and the spider monkey does not have a thumb at all.
The other parvorder within Simiformes is Catarrhini, the Old World monkeys, which are found in Africa. This parvorder includes humans, apes and monkeys, but is divided into superfamilies that separate the humans and apes from the monkeys. The human and ape superfamily is known as Hominoidea, while the monkey superfamily is Cercopithecoidea. Well-known Old World monkeys include proboscis, macaques, langurs, baboons, vervets and guenons. These monkeys are less likely to have tails, and the ones that do are less likely to use them in a prehensile manner.