The most threatened mammal species in the Amazon are the primates, of which the Amazon is one of the most important regions for these mammals. More than 100 species of primates can be found within Brazil, many of which are found nowhere else in the world. 
Primates in the Amazon exist in many forms, from long-limbed spider and wooly monkeys, to smaller capuchin and squirrel monkeys, as well as marmosets and tamarins. Primates help to maintain biological diversity by serving as pollinators and seed disperses within the tropical rainforest. A single spider monkey can disperse over 195,000 seeds over the course of one year, greatly helping the regeneration of the rainforest.  Of the 199 taxa of primates in the Neotropics, however, 35% are listed as threatened by the IUCN.
- Costa, LP et al (2005) Mammal Conservation in Brazil. Conservation Biology, 19 (3), 672-679
- Link, A. et al (2006) Seed dispersal by spider monkeys and its importance in the maintenance of neotropical rainforest diversity. Journal of Tropical Ecology. 22, 235-246.