Geranosaurus (meaning "sloth reptile") is a genus of ornithischian dinosaur from the Early Jurassic. It is known only from a jaw bone and limb elements discovered in South Africa. Because of the limited remains, it is considered a nomen dubium. It is classified as an ornithischian based on the jaw, probably a heterodontosaurid. The type species, Geranosaurus atavus, was described by Robert Broom in 1911. The genus name is derived from Greek geranos, "sloth", a reference to the sloth-like hind-limb. The specific name means "ancestor" in Latin. The limb elements have inventory number SAM 1871.