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NEW WORLD MONKEYS
FAMILY CALLITRICHIDAE

     There are two families of New World monkeys alive today: the family Callitrichidae (the marmoset on the left of the picture above) and the family Cebidae (which includes the howler monkey on the right).    The family Callitrichidae includes marmosets and tamarins.  Marmosets and tamarins are small tree dwellers.  They have claws on the tips of most digits with a flat nail only on the thumb.  Females are usually larger than males.  Species of this family possess 7 cervical vertebrae, 11-13 thoracic vertebrae, 6-8 lumbar vertebrae, 2-3 sacral vertebrae, and 25-33 caudal vertebrae.  Their brains are not as complex as those of other monkeys and the surface of their cerebrum is smooth.  Insects compose most of their diet but they can also include fruits, seeds, and birds in their diet.  Social groups include families in which males help in the care of the offspring.  The pygmy marmoset Cebuella pygmaea is the smallest monkey in the world with a head and trunk length of 13 cm ((Preston-Mafham, 1992; Anderson, 1967).

     One species, the Bare-ear of Silvery Marmoset (Callithrix argentata), is known from Paraguay.  Its range extends northward into Brazil and Bolivia but deforestation and capture for pets are causing a decline in its numbers.

MARMOSET SKULL

marmoset skull

marmoset skull

FAMILY CEBIDAE

     Most cebid monkeys have a fairly flat face (except in Alouatta) and a rounded skull without an occipital projection (except in Saimiri).  Species of this family possess 7 cervical vertebrae, 12-15 thoracic vertebrae, 5-8 lumbar vertebrae, 2-5 sacral vertebrae, and 17-34 caudal vertebrae.  Some species possess a baculum.  In some species the clitoris is long and pendulous, especially Ateles.  There is usually one offspring per pregnancy.  Cebids feed primarily on fruits and leaves but eggs and invertebrates can also be included in the diet.  They typically travel in groups composed of as many as 50 individuals.  They may reach 25 years in age (Anderson, 1987). 

HOWLER MONKEYS

     There are six species of howler monkey known in South America of which one species, the black howler monkey (Alouatta caraya) lives in Paraguay.  Howler monkeys are large monkeys and have the loudest voices among New World monkeys.  In all species, females are about ¾ the size of males and in the species that inhabits Paraguay, males are black while the females are a light brown.  They feed exclusively on plant material, although their digestive tract has no obvious specialization for this diet.  They have prehensile tails and move about through forests in groups which can include up to 25 individuals.  Habitat destruction is causing a great reduction in its numbers.  For example, thousands of howler monkeys were killed in the deforestation of Matto Grosso, Brazil, during the early 1970s (Preston-Mafham, 1992; Wolfheim, 1983). 

howler skull

howler skull

Note the size of the lower jaw in howler monkeys.

howler skull  

NIGHT MONKEYS

     The night or owl monkey (Aotus azaraii) is limited to the western half of Paraguay.  This monkey is easily recognized because of its large eyes and it is the only nocturnal monkey in South America (and is also the only nocturnal monkey in the world).  It feeds primarily on fruits and other plant material but can also include small animals in its diet.  Family groups travel together.

owl monkey skull

TITIS

     The range of dusky titis (Callicebus moloch) includes northwestern and north central Paraguay.  It feeds primarily on fruit and insects.  They travel through forests in small clans of parents and offspring (Preston-Mafham, 1992; Wolfheim, 1983).

skull

skull

CAPUCHIN

    The black-capped or tufted capuchin (Cebus apella) is known throughout most of South America and is the most widespread species of New World monkey.  Groups of monkeys range in numbers from two to thirty and home ranges are known to vary from 80 to 150 hectares.   Their diverse diet includes fruit, flowers, leaves, invertebrates, and small vertebrates.  This monkey has been killed for food and to bait traps for jaguars in several countries, including Brazil.  Between 1968 and 1973, more than seven thousand capuchins were imported to the United States (some of which were used in medical research), primarily from Peru and Paraguay.  Peru exported almost 19 thousand capuchins between 1964 and 1974 (Wolfheim, 1983; Preston-Mafham, 1992).

skull

skull

skull

skull