Capuchin Monkeys Place Nuts Strategically
Channel: PLOS Media
Date: 2013-02-28

A bearded capuchin monkey places nuts in a stable position before striking them with a stone to crack them open, showing that monkeys use tactile cues to improve their use of tools. 

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0056182

Citation: Fragaszy DM, Liu Q, Wright BW, Allen A, Brown CW, et al. (2013) Wild Bearded Capuchin Monkeys (Sapajus libidinosus) Strategically Place Nuts in a Stable Position during Nut-Cracking. PLoS ONE 8(2): e56182. doi:10.1371/journal.pone.0056182