This may exemplify a rare example of insular dwarfing in a mainland context, with the "islands" being formed by biogeographic barriers during arid climatic periods when forest distribution became patchy, and/or by the extensive river networks in the Amazon Basin.

The marmosets rely quite heavily on tree exudates, with some species (e.g. Callithrix jacchus and Cebuella pygmaea) considered obligate exudativores.

[8] They are the only primate group that regularly produces twins, which constitute over 80% of births in species that have been studied.

Parental duties may include carrying, protecting, feeding, comforting, and even engaging in play behavior with offspring.

In some cases, such as in the cotton-top tamarin (Saguinus oedipus), males, particularly those that are paternal, even show a greater involvement in caregiving than females.