Pygmy Marmoset, PeruThe pygmy marmoset is the world’s smallest monkey, weighing just 3 to 5 ounces and measuring around 5 inches long (excluding its tail). Native to the Amazon rainforest, it uses sharp lower teeth to gouge tree bark and feed on sap and gum. I saw quite a few of them over two trips to the Loreto region of Peru in the upper Amazon basin. Nikon D500 with Nikkor 500mm PF lens, ISO 800, f/5.6 at 1/200th of a second.