Which tiny Amazon rainforest monkey is the world’s smallest true monkey species?

The pygmy marmoset is the world’s smallest true monkey species and lives in western Amazonian rainforests.

This New World monkey usually weighs about 100 grams and has a body length of roughly 12 to 15 centimetres, excluding its tail. Its small size helps it move through fine branches and dense vegetation.

Pygmy marmosets mainly eat tree sap, gum, latex, fruit, and insects. Their specialized lower incisors help them gouge bark and reach plant exudates. They commonly live in family groups and communicate with high-pitched calls.

The pygmy marmoset is sometimes loosely called the world’s smallest monkey, but the phrase “true monkey” distinguishes it from other tiny primates such as mouse lemurs, which are lemurs rather than monkeys.