Back To CourseHigh School Biology: Help and Review
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Primates is the name of the order of mammals to which we happen to belong. The name means 'first' or 'most important' and was given to the order by Carl Linnaeus. While naming it that way may have been a matter of human ego, we can't help but feel a certain fascination with the group to which we belong.
Primates typically have grasping hands and feet in addition to relatively large brains. They have flatter faces than most other mammals, lacking the muzzle of dogs, bears, deer and other mammals. They have good vision but a more limited sense of smell than most other mammals. Most are highly social.
Primates may have evolved from insectivores, or animals that live off insects. The primate family tree itself goes back at least 55 million years. We know this because fossils classified in the genus Archicebus are believed to date back to the late Cretaceous Period, just before the end of dinosaurs.
The most primitive living primates are called prosimians. They are primitive in the sense that they retain characteristics of the very first primates from millions of years ago. Prosimians include lemurs, lorises, galagos and tarsiers.
The other main group of primates, the simians, likely evolved after the prosimians. This group includes the new world monkeys, which have tails and are considered to be relatively primitive. These monkeys are native to North and South America, aka the 'New World.' Many have prehensile tails, which is an adaptation that few other primates share.
The rest of the simians, called anthropoids, include old world monkeys, apes and hominids, including humans. Old world monkeys evolved first, followed by apes and then hominids. These species are native to Europe, Africa and Asia.
This family tree shows the origin of primates, as well as the time when each major primate group split off on its own evolutionary branch.
As you can see, prosimians developed first, followed by simians. To put it differently, lemurs and lorises' ancestors branched off first, followed by tarsiers, then new world monkeys, then old world monkeys, then apes. Humans came about relatively late in the game.
There are four main groups of prosimians: galagos, lemurs, lorises and tarsiers. Prosimians' brains are not exceptionally large compared to other mammals. Most have wet, dog-like noses.
Galagos are fast, agile jumpers that live in Central Africa. They can leap very far for their size and tend to hunt insects. They are nocturnal and probably evolved in that niche to avoid competition with other primates. Galagos have good night vision, excellent hearing and long tails for balance. They tend to be far faster and more active than lorises and tarsiers. Galagos are often called bush babies.
Lemurs live exclusively in Madagascar, although their fossils are found on mainland Africa. They have wet noses like dogs and a keen sense of smell. Lemurs range greatly in size, from the tiny mouse lemur to the 20-pound indri. At present, there are about 50 recognized lemur species. Their diversification into many species within a relatively small habitat was the result of resource partitioning. This process occurs when food and habitat are limited, so animals specialize in their diet and behavior.
Lorises are slow-moving, nocturnal primates that mostly eat insects. They have large eyes and a distinct appearance, with grasping hands and feet that wrap around branches. There are about ten species living in India and Southeast Asia.
Tarsiers are also generally nocturnal. While considered prosimians, they are actually genetically closer to simians than to the other prosimians. One trait that sets them apart from other prosimians is their dry nose. Tarsiers have strong hind legs for jumping after prey. They also have very large eyes that are as large as their brains. Their eyes are so large that they cannot turn them, but they can turn their heads around like owls.
Simians include monkeys, apes and hominids. They have less of a sense of smell than prosimians but bigger brains.
New world monkeys live in North and South America. Some new world monkeys have prehensile tails that let them grasp tree branches. Most lack opposable thumbs. Their nostrils face out to the side. Most are also arboreal, living in trees. They tend to be more monogamous than old world monkeys and show more intense parental care.
New world monkeys range in size from the 6-inch pygmy marmoset to the 30-pound southern muriqui. There are five living families of new world monkey.
Anthropoids are old world simians. These include old world monkeys, apes and hominids. Anthropoids are considered to be the most advanced primates.
Old world monkeys have downward-facing nostrils. Some are arboreal, but many live on the ground. They range in size from the talapoin, which weighs about 3 pounds, to the mandrill, which can weigh more than 100 pounds. Some old world monkeys lack tails. None of them have prehensile tails, which would be used for grasping, like the tail of a possum.
Apes and humans belong to the group called hominoids, which are upright apes. Hominoids include the lesser apes, the great apes and the hominids.
Hominoids are able to lift their arms directly over their heads, an ability that is useful for brachiation - the process of swinging through the trees by one's arms. They lack tails and have more advanced brains and thinking ability.
The great apes include orangutans, gorillas, bonobos and chimps. All of the great apes have shown advanced learning abilities, problem-solving, tool use and tool construction. Some have learned an impressive amount of sign language. More importantly, they have all passed the mirror test, which means that they are able to recognize their own faces in a mirror.
The lesser apes include almost 20 species of gibbon plus the siamang. The gibbons are highly specialized for brachiation. Their arms are especially long and strong. Smaller than the great apes, they are more fully arboreal. The siamang is similar to the gibbon, but the male has a throat pouch that inflates when he does his loud mating call.
Hominids are the group to which humans belong. All upright walking hominoids are called hominids. These include the various Australopithecus species such as the famous 'Lucy' fossil, Australopithecus afarensis. Other hominids include extinct human ancestors such as Homo habilis, Homo erectus and Homo neanderthalensis.
Primates are mammals that usually have grasping hands, large brains and flat faces that set them apart from other mammals. Humans, gorillas, lemurs and tarsiers are all examples of primates. Primates evolved relatively recently, with fossil evidence pointing to an origin of about 55 million years ago.
|Primates||the name of the order of mammals to which we happen to belong, typically have grasping hands and feet in addition to relatively large brains with flatter faces than most other mammals, lacking the muzzle of dogs, bears, deer and others|
|Prosimians||most primitive of the primates and includes lemurs, lorises, galagos and tarsiers|
|Galagos||fast, agile jumpers that live in Central Africa|
|Lemurs||live exclusively in Madagascar, have wet noses like dogs and a keen sense of smell|
|Resource partitioning||occurs when food and habitat are limited, so animals specialize in their diet and behavior|
|Lorises||slow-moving, nocturnal primates that mostly eat insects|
|Tarsiers||generally nocturnal, considered prosimians, are actually genetically closer to simians than to the other prosimians|
|Simians||include monkeys, apes and hominids|
|New world monkeys||live in North and South America and some have prehensile tails that let them grasp tree branches|
|Anthropoids||advanced primates, old world simians that include old world monkeys, apes and hominids|
|Old world monkeys||have downward-facing nostrils and are arboreal, but many live on the ground|
|Hominoids||are upright apes, which include apes and humans|
|Great apes||include orangutans, gorillas, bonobos and chimps|
|Lesser apes||include almost 20 species of gibbon plus the siamang|
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Back To CourseHigh School Biology: Help and Review
36 chapters | 570 lessons