Some have only small thumbs or none at all. Nevertheless, they are have dextrous hands and are good at handling objects and moving along branches. In contrast, however, they have a large big toe which strongly opposes the other digits. Cebids don't have cheek pouches to collect food in. Cebids have large, well developed eyes.
Males remain in their natal troop.
Most are very noisy with a wide range of calls. Previously, it ranged throughout east and southeast Brazil. It is now among the world's rarest mammals. Animal Diversity Web info on family cebidae including the Howler Monkey, Owl Monkey, Titi Monkey, Squirrel Monkey. Johns Hopkins UnivPress, 1991.