Pete Oxford / Brown Capuchin (Cebus apella) stabilizes itself with its prehensile tail while using a heavy rock hammer to crack open palm nuts placed in small pits in the anvil rock surface, Cerrado habitat, Brazil

Pete Oxford / Brown Capuchin (Cebus apella) stabilizes itself with its prehensile tail while using a heavy rock hammer to crack open palm nuts placed in small pits in the anvil rock surface, Cerrado habitat, Brazil

Pete Oxford / Brown Capuchin (Cebus apella) pair using rock and anvil to crack open Piassava Palm (Attalea funifera) nuts, Cerrado habitat, Piaui State, Brazil

Pete Oxford / Brown Capuchin (Cebus apella) using a rock to crack open a Piassava Palm (Attalea funifera) nut, Cerrado habitat, Piaui State, Brazil

Pete Oxford / Brown Capuchin (Cebus apella) using a rock to crack open a Piassava Palm (Attalea funifera) nut, Cerrado habitat, Piaui State, Brazil

Chien Lee / Long-tailed Macaque (Macaca fascicularis) troop feeds on oil palm nuts washed downriver from a plantation, Kinabatangan Wildlife Sanctuary, Sabah, Borneo, Malaysia

Yukihiro Fukuda / Young Japanese macaque (Macaca fuscata) eating nut with others foraging, Autumn, Jigokudani, Joshinetsu Kogen NP, Nagano, Japan

Luciano Candisani / Brown Capuchin (Cebus apella) using a rock as a hammer to crack a palm nut, Gilbues, Brazil

Luciano Candisani / Brown Capuchin (Cebus apella) using a rock as a hammer to crack a palm nut, Gilbues, Brazil

Pete Oxford / Brown Capuchin (Cebus apella) pair using rock and anvil to crack open Piassava Palm (Attalea funifera) nuts, Cerrado habitat, Piaui State, Brazil

Pete Oxford / Brown Capuchin (Cebus apella) stabilizes itself with its prehensile tail while using a heavy rock hammer to crack open palm nuts placed in small pits in the anvil rock surface, Cerrado habitat, Brazil

Pete Oxford / Brown Capuchin (Cebus apella) stabilizes itself with its prehensile tail while using a heavy rock hammer to crack open palm nuts placed in small pits in the anvil rock surface, Cerrado habitat, Brazil