Primate Classification

They have long flexible backbones, five-fingered gripping hands and feet and forward pointing eyes on a short, flexible neck. Their forearms are linked to the chest by a collar bone (clavicle) which allows them to hang without straining their shoulder muscles. Like many other tree dwelling mammals, most primates have long tails to help them balance, and some also have prehensile tails.

Prehensile Skull

Compared to their body size, primates have a bigger and more complex brain than other animals. The structure of the skull shows that the primates depend more on sight than on smell. All primates have both eyes facing forward, on the front of the face and enclosed in bony sockets, so that the view seen by one eye overlaps that of the other. Called "stereoscopic" vision, this gives a clear, three-dimensional image. Thus, primates are good at judging distances, an important ability for life in the trees.

The basic structure of the primate eye is similar to other mammals. But while most mammals have only black and white vision, colour vision is the norm in primates which are active during the day (diurnal).

Prehensile Hands

Primates have hands that grasp and not paws. Primates have a well-developed sense of touch with many sense organs on the tips of fingers and toes. Except for marmosets and tamarins, all primates have flat fingernails and toenails instead of claws. They also have two separate bones on their forearms (radius and ulna) which allows them to rotate their hands (palm up and palm down). This is important also for primates that swing from branch to branch (brachiation). All primates except humans also have opposable big toes, so they can grasp branches with their feet.

What is a prehensile tail? Prehensile tails can curl around a branch and suspend the full weight of the animal from it, like a fifth limb. The tail is able to grip so well because up to one-third of the underside at the tip of the tail consists of bare skin, which looks exactly like the palm of a dark hand. There is even a pattern of tiny ridges, like a fingerprint, on this sensitive area. This gives the monkey a very firm grip when the tail is curled round a branch. The tail also has a lot of muscles, which makes it strong.

Scent is of some importance, especially in prosimians, which still depend more on smell than higher primates. Those with colourful patterns help them to identify their own species, particularly where several different species may forage together for safety. To express their moods, primates also use facial expressions, different body postures, fluff up their fur, or hold their tail in different positions.

With the exception of man, primates walk on all fours. But limb length varies with their method of locomotion. Primates which clamber around in trees on all fours are usually relatively short-limbed. Ground-dwelling primates, which may need speed to run to safety tend to be fairly long-limbed. Highly arboreal primates, such as the gibbons, which swing from branch to branch, have very elongated forelimbs; while those which leap from branch to branch and from tree to tree have elongated hind-limbs).

Most primates are social and communicate their moods and intentions to each other in a number of distinctive ways. Sound is also very important for nocturnal species which forage in the dense forest canopy in groups. The sounds produced depends on the situation: just to keep in touch when feeding, demarcate territories and warn off potential intruding groups, alert others of danger from the air or ground. Some species like the lemurs, have developed different types of alarm calls to specify the location of the danger (in the trees, air, ground) and type of predator (snake, bird of prey, other mammals).

Primate mothers carry their young on their bodies until they are weaned; the ties between mother and baby are very strong.

Like all mammals, all primates are are covered with hair. Their hair colours and patterns allows primates to recognize their own and other species and in some to tell the difference between males and females.

 

Many primates are omnivorous, although most eat mainly plant food.

There are about 200 species of primates, including monkeys, lemurs, chimps, humans, and others. Primates are divided into three groups:

·        Tree shrews

·        Tupaiidae: Tree shrews

·        Prosimians

·        Cheirogaleidae: Dwarf lemurs

·        Lemuridae: Large lemurs

·        Megaladapidae: Sportive lemurs

·        Indridae: Leaping lemurs

·        Daubentoniidae: Aye-Aye

·        Loridae: Lorises and galagos

·        Tarsiidae: Tarsiers

·        Anthropoids

·        Callitrichidae: Marmosets and tamarins

·        Cebidae: New World Monkeys (like the Howler monkey)

·        Cercopithecidae: Old World monkeys (like the mandrill)

·        Hylobatidae: Lesser Apes (Gibbons and siamangs)

·        Hominidae: Great Apes (like gorillas, chimps, and orangutans) and humans

The prosimians or lower primates (Prosimii)
Prosimian means "before apes. They have few similarities to humans, and are mostly small and nocturnal. All found in the Old World only. The families include the lemurs (Lemuridae, Indriidae) loris, pottos, bushbabies (galagos) (Lorisidae), tarsiers (Tarsiidae), Aye Aye (Daubentoniidae). Previously, the Tupaiidae were included here, but now are assigned a separate order, Scandentia.

The Anthropoids or higher primates (Anthropoidea)
Most are larger and diurnal. Comprise apes (no tails) and monkeys (nearly all have tails).

New World: all monkeys. Fairly small and exclusively tree dwelling. Marmosets and tamarins (Callitrichidae), Cebids (Cebidae) capuchins & squirrel monkeys, spider & woolly monkeys, howler monkeys, sakis & uakaris, night monkeys, Titi monkey

Old World: comprise monkeys, apes and humans. Bigger and spend more time on the ground. Macaques, Baboons, Mandrills and Drills, Geladas, Mangabeys, Guenons, Leaf-eating monkeys (Langurs, leaf monkeys, colobus, proboscis) (Cercopithecidae)

Apes: Lesser Apes Gibbons and siamang; Great Apes: Orang Utans, Gorillas, Chimpanzees and Bonobos (Pongidae) and humans (Hominidae).