The first photo was taken in a forest remnant near Vila Bela de Santíssima Trindade, Mato Grosso, while the 2 Capuchins in the second photo were members of a troop of about 30 that were moving through the grounds of the Hotel Floresta Amazonica in Alta Floresta. The 3rd photo was taken at Carajás and shows a Capuchin holding a Brazil nut. It was moving from one tree to another crossing the track when it spotted me and dropped the nut.

They are similarly catholic in their food eating fruit, seeds and insects as well as (apparently) Brazil nuts which I suspect they must pick up when already opened by an agouti or some other animal because I can't think that a Capuchin could open a Brazil nut unaided.

They are the classic organ-grinder's monkey.

There is an illustration in Eisenberg, Plate 9