The term “New World monkey” is a broad label that refers to any species that falls under one of the five taxonomic families of the Ceboidea superfamily: Cebidae, Callitrichidae, Atelidae, Pitheciidae, and Aotidae.
There are 23 genera and 179 species of New World monkeys distributed across southern Mexico and South and Central America.
Many different types of New World monkeys exist, including howler monkeys, marmosets, capuchins, sakis, night monkeys, tamarins, and more.
Characteristics of New-World Monkeys
Here are the main characteristics shared by New World monkeys:
Diet
The diet of New World monkeys cannot simply be generalized—it largely depends on the particular species in question. Nevertheless, some of the common foods eaten by these monkeys are fruits, insects, tree gums, and seeds; many species are primarily frugivores or insectivores[1].
Gestation/Reproduction
For the most part, smaller New World monkeys tend to stick to monogamy, while larger species are more likely to be polyamorous[2]. Interestingly, unlike many other primate groups, female New World monkeys do not have periods. It should also be noted that although the gestation period of New World monkeys varies by species, it is usually around 145 days (about 5 months).
Tail
All New World monkeys possess tails; in certain species, they are prehensile, meaning they can be used to grasp and hold objects, acting like a fifth limb of sorts[5].
One of the most well-known uses in monkeys is to dangle from a tree branch (by tightly wrapping the prehensile tail around it). It should be noted that only 4 genera of New World monkeys have these useful appendages: Ateles (spider monkeys), Lagothrix (woolly monkeys), Brachyteles (woolly spider monkeys), and Cebus (capuchin monkeys)[6].
Body Size
In general, New World monkeys are mainly small to medium-sized. Specifically, the smallest New World monkey species in the world is the pygmy marmoset (Finger Monkey) (Cebuella pygmaea); it weighs around 3 to 5 ounces and can be 4 to 6 inches long[7].
On the other hand, one of the largest New World monkey species is the Yucatan black howler monkey (Alouatta pigra), which can weigh up to 11.4 kilograms, and is about 26 inches long[8].
Teeth
All New World Monkeys share a dental formula of 2.1.3.3[9]. This essentially means that each quadrant of the mouth has 2 incisors (which are used to bite food directly) and 1 canine (which is used to tear food), as well as 3 molars and premolars each (both of which are used to chew food).
Social Behavior
The social groups and structures of New World monkeys vary between species. For instance, some genera live in small groups consisting of only close family (mates and children). Conversely, other genera live in large groups made up of many different families; these groups can be made up of as many as 50 to 60 individuals [10].
Eyes
New-World monkeys are known for their large eyes; however, the quality of their color vision varies between species. For example, in some species, all males possess dichromatic vision (meaning they only have two cone cells in their retinas that perceive color), while females’ vision can either be trichromatic (which means they have three cone types in their retinas), or dichromatic like males[11].
On the other hand, all species of howler monkeys, male and female, have been found to have a trichromatic vision[12].
Limbs
All New-World monkeys possess relatively long limbs and have a locomotor pattern of quadrupedal walking[3]. It is also worth mentioning that the thumbs of New World monkeys, unlike Old World monkeys, are not opposable (meaning they cannot move independently from the hand)[4].