Extant Euarchontoglires


Order: Primates
Family: 11
Species: 356

Primates are traditionally divided into three groups; apes, monkeys and prosimians. However, they have been recently re-divided into two Suborders: Strepsirhini (comprising lemurs, galagos, lorises and pottos) and Haplorhini (comprising tariers, apes and monkeys). There is debate as to the phylogeny of tarsiers, but are currently considered as members of the Haplorhini. Apes are distinguished most easily from the mokneys and prosimians due to their lack of tail.



The Ape family are divided into the lesser apes (the gibbons) and the great apes (gorillas, orang-utans, chimpanzees, bonobos and humans). Apes have a very upright posture in comparison to other primates. This is facilitated by a shortened spine and a relatively short and broad pelvis. Combined, these anatomical features allow for a lower centre of gravity and a more bipedal tendency of locomotion. Apes' shoulder blades are positioned at the back, allowing for a wide range of movement in the shoulder joints. The orang-utan is the largest arboreal mammal, weighing up to 80 kg.

Lesser apes form monogamous pairs that mark treetop territories with loud musical songs. A young male or female without a mate will sing alone until a bond is formed, and a joint territory can be established. In contrast, great apes are polyonous with the dominant male being able to mate with any female. Orang-utans are the only solitary great ape, but have the 'right' to mate with any female that enters his territory. Bonobos, chimpanzees and gorillas live in well defined social groups with complex hierarchical systems. Chimpanzees form troops of between 40 and 100 with a dominant male, hunting parties and grooming rituals to forge bonds. Gorillas have much smaller troops of between 5 and 10, but still have a dominant male (a silverback) with possible only one or two other males (young sons or younger brothers of the silverback).


Example species

Western lowland gorilla
Gorilla gorilla

Length: 1.3-1.9 m
Weight: 68-200 kg
Social unit: Group
Region: Central Africa
Status: Endangered

Female Western lowland gorilla and infant (Gorilla gorilla)
Bristol Zoo and Gardens, UK

(Click on image for a larger picture)


Bornean orang-utan
Pongo pygmaeus

Length: 1.1-1.4 m
Weight: 40-80 kg
Social unit: Individual
Region: South-East Asia
Status: Endangered

Male and female Bornean Orang-utans (Pongo pygmaeus)
Phoenix Zoo, Arizona, USA


Homo sapien sapien

Length: 1.7 m
Weight: 80 kg
Social unit: Group
Region: Worldwide
Status: Dangerously common



Monkeys are subdivided into New World Monkeys (smaller species such as marmosets and spider monkeys) and Old World Monkeys (the larger species such as baboons, colobus monkeys and langurs). These two groups are relatively separate geographically and are distinguished morphologically by nose shape. Monkeys are separated form apes and prosimians by a flattened chest, a large brain, sharp canine teeth, a hairy nose and a deep lower jaw. They are fundamentally quadrapedal but can stand on their hind legs to free their dextrous hands for fruit picking, etc. Old World monkeys are more closely to apes and as such are larger, and have hard sitting pads on their rumps, which New World monkeys do not have. New Worlds also have downwards or forwards pointing nostrils and a broad nasal septum.

The social groupings within New World monkeys vary greatly. Marmosets have a small group comprising a dominant monogamous pair plus several adolescent offspring that help in rearing younger siblings. In contrast squirrel monkeys live in large mainly female groups of around 100. Spider monkeys also have large social groups, but they split into several smaller groups when foraging. Old World Monkeys normally display just one of two organisations. The baboons and macaques for example live in large multi-male troops. Monkeys such as mandrills, gelada and langurs live in harems, where a single adult dominant male has a group of mostly females. No matter what the social group arrangement though, grooming is extremely important in forging bonds and expressing dominance.


Example species:

Black spider monkey
Ateles chamek

Length: 40-52 cm
Weight: 9.5 kg
Social unit: Group
Region: West South America
Status: Lower risk

Male black spider monkey (Ateles chamek)
Dudley Zoological Gardens, UK


Squirrel monkey
Saimiri boliviensis

Length: 27-32 cm
Weight: 950 g
Social unit: Group
Region: West to Central South America
Status: Lower risk

Squirrel monkey (Saimiri boliviensis)
Bristol Zoo and Gardens, UK

(Click on image for a larger picture)


Eastern black and white colobus
Colobus guerez

Length: 52-57 cm
Weight: 8-13.5 kg
Social unit: Group
Region: Central and East Africa
Status: Lower risk

Eastern black and white colobus monkey (Colobus guerez)
Woburn Safari Park, UK


Mandrillus sphinx

Length: 63-81 cm
Weight: 11-37 kg
Social unit: Group
Region: West Central Africa
Status: Vulnerable

Male and female mandrills (Mandrillus sphinx)
Phoenix Zoo, Arizona, USA



The prosimians are the most primitive of the primates. They comprise the lemurs from Madagascar, the galagos and pottos from Africa and the lorises of Asia. The lemurs (including the sifakas, indri and the aye-aye) are the largest of the Prosimians, and have large bodies, elongated limbs, a long tail and large ears. The smaller lorises, pottos and galagos have larger eyes and shorter tails. Most Prosimians are nocturnal such as the aye-aye of Madagascar, who is so nocturnal that they were thought to be extinct until rediscovered in 1957. A few lemurs however, are diurnal such as the ring-tailed lemur who spends a lot of time sunbathing. Prosimians have a more acute sense of smell than other primates and are mostly arboreal. Their hands and feet are specially adapted for grasping branches and run or leap between branches in a quadrapedal gait.

Black and white ruffed lemur (Varecia variegata variegata)
Dudley zoological gardens, UK


Example species:

Daubentonia madagascariensis

Length: 40 cm
Weight: 2.5-3 kg
Social unit: Variable
Region: North-West and East Madagascar
Status: Endangered

Aye-aye skeleton (left) and Natural History Collection (right)
(Daubentonia madagascariensis)
Bristol City Museum


Ring-tailed lemur
Lemur catta

Length: 39-46 cm
Weight: 2.5-3.5 kg
Social unit: Group
Region: South and South-West Madagascar
Status: Vulnerable


Ring-tailed lemur (Lemur catta)
Dudley Zoological Gardens, UK



Author: Emma-Louise Nicholls
Last updated: 20th November 2005
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Websites produced by students on the MSc Palaeobiology programme in the Department of Earth Sciences at the University of Bristol for academic year 2005-6