Called the Ravenous Maw, Azuvidexus was demon lord of primeval beasts and scaled nightmares eons ago, the ruler of a steaming, jungle-covered Layer of the Abyss known as N'gharl. Demogorgon wished to do away with them, so he cleverly created an alliance with him to establish a cult on the Material+Plane in a region guarded by a particularly territorial Pantheon of deities.
Azuvidexus himself was reincarnated, in a way, by Demogorgon, who transplanted the seed that once was N'gharl and transported it to the Material+Plane, where it formed a demonic region called the Crawling Jungle. Azuvidexus is Demogorgon's thrall, trapped in the body of a dinosaur.
Source: Dragon #357