New World monkey

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Old World and New World monkeys

Know why New World monkeys evolved prehensile tails while Old World monkeysdidn't

New World monkey

mammal

Also known as: Platyrrhini, platyrrhine

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July 23, 2026

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Old World and New World monkeys — Old World and New World monkeys Old World and New World monkeys.

New World monkeys are a group of primates found in tropical forests of Central and South America. They are distinguished from Old World monkeys by their broad noses with outwardly directed nostrils and the absence of ischial callosities (sitting pads) on their buttocks. Many New World monkeys also possess prehensile tails, which can support their body weight or grasp objects.1

These monkeys are known for their intelligence and curiosity. They are primarily arboreal, moving through trees on all four limbs, and are active during the day. Their diet consists of vegetation, insects, and small animals. Examples include squirrel monkeys, capuchins, spider monkeys, and howler monkeys. Squirrel monkeys, for instance, are known for forming large social groups and communicating with a variety of calls.12

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Amazon River
Animal life
…forest are several species of monkeys. Of note are the howler monkeys, which make the selva resound with their morning and evening choruses. The small, agile squirrel monkey, the most ubiquitous of Amazonia’s monkeys, is used in laboratories, as is the larger spider monkey. Among a host of other primate…
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…forest are several species of monkeys. Of note are the howler monkeys, which make the selva resound with their morning and evening choruses. The small, agile squirrel monkey, the most ubiquitous of Amazonia’s monkeys, is used in laboratories, as is the larger spider monkey. Among a host of other primate…
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primate
The brain
…marmosets, but in the larger New World monkeys (capuchins, for instance), the cerebrum is richly convoluted. Gyri and sulci are well marked in Old World monkeys and in the apes, the complexity of the pattern closely approximating the tortuous mazelike pattern seen in humans.
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…marmosets, but in the larger New World monkeys (capuchins, for instance), the cerebrum is richly convoluted. Gyri and sulci are well marked in Old World monkeys and in the apes, the complexity of the pattern closely approximating the tortuous mazelike pattern seen in humans.
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primate
Oligocene
The earliest platyrrhine fossils were found in South America and are only about 25 million years old, so much remains to be learned about their earliest evolutionary history.
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The earliest platyrrhine fossils were found in South America and are only about 25 million years old, so much remains to be learned about their earliest evolutionary history.
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primate
Snouts, muzzles, and noses
…distinguishing Old World monkeys from New World monkeys at a glance. In New World monkeys (the Platyrrhini, meaning “flat nosed”), the nose is broad, and the nostrils are set wide apart, well separated by a broad septum, and point sideways. In the apes and Old World monkeys (the Catarrhini, meaning…
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…distinguishing Old World monkeys from New World monkeys at a glance. In New World monkeys (the Platyrrhini, meaning “flat nosed”), the nose is broad, and the nostrils are set wide apart, well separated by a broad septum, and point sideways. In the apes and Old World monkeys (the Catarrhini, meaning…
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primate
General structure
…overlooked that many lemurs and New World monkeys do enjoy a rich olfactory world, especially in the social sphere.
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…overlooked that many lemurs and New World monkeys do enjoy a rich olfactory world, especially in the social sphere.
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primate
Teeth
…premolars; primitive primates, tarsiers, and New World monkeys have retained three on each side of each jaw, but in the apes and Old World monkeys, there are only two premolars. The primitive premolars are uniform in shape and are unicuspid, but in primates the most posterior premolar tends to evolve…
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…premolars; primitive primates, tarsiers, and New World monkeys have retained three on each side of each jaw, but in the apes and Old World monkeys, there are only two premolars. The primitive premolars are uniform in shape and are unicuspid, but in primates the most posterior premolar tends to evolve…
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