What Is an Animal That Begins With the Letter "U"?

Uakaris are small monkeys that live in South American tropical forests. They have very unusual faces, and their entire heads are bare of hair, from the crowns of their heads to the tips of their chins. They are extremely lean, so their faces have a skull-like appearance. They have projecting lower incisors. Uakaris are also unusual in that their tails are disproportionately short for their bodies. There are four species, one of which, Cacajao calvus, has bright red skin on its face; the other three species have black faces.