MOUSE LEMUR

Although the Pygmy marmoset's are the smallest monkey species, the mouse lemur is the smallest primate in the world, according to National Geographic. These nocturnal Madagascar residents weigh between 1 and 4 ounces and grow to between 2.25 and 4.75 inches in height. Their tails, however, can be almost that long, growing to about 4.75 inches.