This mini-monkey could fit in a human’s hand: the pygmy marmoset (Callithrix pygmaea) may look like a tiny squirrel as it dashes through the rainforest canopy of South America, but this primate is actually the world’s smallest monkey. Weighing in at 140 g and growing to be 13 cm long, it has a tail that’s longer than its body—and while not prehensile, it helps this monkey balance in the trees.
Photo: Laura Wolf