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1.6 describe primate characteristics in: prosimians new and old world monkeys apes humans
describe primate characteristics in
- prosimians
- new and old world monkeys
- apes
- humans
- Prosimians (before apes). Prosimians are a group of lower primates including lemurs, tarsiers, lorises and bushbabies. Their faces are often pointed and they have grasping hands and feet. They occur in small isolated groups and are generally endangered. They are small usually nocturnal, arboreal (active at night, live in trees) animals with forward facing eyes. Prosimians have a wet nose, called a rhinarium, which is an adaptation for the sense of smell.
Summary of prosimian features:
- small nocturnal arboreal primates
- at least one digit with a claw instead of a nail
- less opposable thumb than other primates
- grooming claw as well as nails
- more acute sense of smell than other primates
- long snout with a rhinarium
- eyes more on the side of the head than other primates
- seasonal breeding.
Prosimians have many characteristics that differ from other primates. The primate characteristics of this group include:
- arboreal
- presence of nails on at least one digit
- opposable thumb but less than other primates
- forward facing eyes but less than other primates
- New and old world monkeys. Monkeys are divided into new and old world monkeys. New world monkeys live in the Americas and old world monkeys come from Asia and Africa. They are usually larger than prosimians and are diurnal (active during the day). They are generally tree dwellers have a larger brain than prosimians and have full binocular vision. They do not have a rhinarium. Differences between new and old world monkeys are summarised in the table below:
Feature |
Old world monkey |
New world monkey |
prehensile tail (able to grasp objects)
|
absent
|
present
|
nostrils
|
pointing forward, shaped like tear drops, close together
|
pointing sideways, nostrils round and wide apart
|
nose partition
|
narrow
|
wide
|
cheek pouches
|
present
|
absent
|
callosities (coloured area on the rump)
|
common
|
absent
|
Examples of New World monkeys include tamarins, squirrel monkeys, spider monkeys, capuchins and howler monkeys. Examples of old world monkeys include baboons, macaques, mandrills and proboscis monkeys.
- Apes. Apes have no tails. Most are larger than monkeys and they have a larger brain relative to their body size. They rely on sight rather than smell and live in organised social groups. Apes include gibbons, orangutans, gorillas and chimpanzees.
Summary of ape features:
- forward facing eyes
- more opposable digits
- nails
- good colour and stereoscopic vision
- menstrual cycle
- no tail
- shoulders adapted for brachiation (swinging arm over arm)
- large size.
- Humans. Humans are the only living members of the hominin group. They are large primates with an upright stance and bipedal locomotion. The big toe is not opposable and the knees are locking. The pelvis of humans is broad and barrel-shaped. The legs are longer than the arms and the thighbone angles inwards. Human feet are flat and humans live on the ground. The dental arch in gorillas is U-shaped while in humans it is parabolic.