Zookeeper Sarah Jurgens holds Reillo, a Pygmy Marmoset, also known as dwarf monkey, on June 2, 2011, in Lincoln, Nebraska. Born weighing the equivalent of three ten-cent pieces and only as long as a human thumb, little Reillo may be the world's smallest monkey. Abandoned by his parents soon after birth, Reillo was nursed to health by 26-year old Jurgens, his human mum. Now three months old and chirping at the sight of her, little Reillo has grown to five inches long and a healthy 60 grams, and is thought to be the world's only surviving hand-raised marmoset this year. [Photo/CFP]