One of the cursed children of the evil spirit Tau(click that link, it is worth a read in itself) and pursued human woman Kerana,the Ao Ao is one of the central mythological creatures among Guarani-speaking cultures.
It was hard to get a good idea of what this monster is said to resemble. I’ve read “a voracious sheep-like creature with a massive set of fangs”, as well as “a large, carnivorous peccary”. Yet nearly all the illustrations and sculptures I have seen in my research lead to a hoofed thing on its hind legs with long monkey arms. The face, in some, does have a sheep or boar-like quality and the fangs are certainly always there. So, in the end, I went with my own interpretation. The Ao Ao gets its name from its howling, “Ao ao ao!” when it is pursuing its victims.
Possessing great reproductive powers, it is sometimes known as a Guaraní spirit of fertility.
Ao Ao’s sole source of food is people. Since it is at least half-human by birth, it can possibly be considered a cannibal. It will pursue its intended victim over any distance and over any terrain, not stopping until it has had its meal. If the person tries to escape by climbing a tree, the Ao Ao will keep circling the tree, howling incessantly and digging at the roots until the tree falls. The only way to successfully escape from an Ao Ao is to climb a palm tree. The palm contains an as yet unknown power against the Ao Ao, and if its intended victim did climb one, the Ao Ao will howl and scream in defeat before finally leaving.