Heterodontosauridae includes the genera "Abrictosaurus", "Lycorhinus", and "Heterodontosaurus", all from South Africa. While Richard Thulborn once reassigned all three to "Lycorhinus", all other authors consider the three genera distinct. Within the family, "Heterodontosaurus" and "Lycorhinus" are considered sister taxa, with "Abrictosaurus" as a basal member. "Geranosaurus" is also a heterodontosaurid, but is usually considered a "nomen dubium" because the type specimen is missing all its teeth, making it indistinguishable from any other genus in the family. More recently, the genus "Echinodon" has been considered a heterodontosaurid in several studies. "Lanasaurus" was named for an upper jaw in 1975, but more recent discoveries have shown that it belongs to "Lycorhinus" instead, making "Lanasaurus" a junior synonym of that genus. "Dianchungosaurus" was once considered a heterodontosaurid from Asia, but it has since been shown that the remains were a chimera of prosauropod and mesoeucrocodylian remains. José Bonaparte also classified the South American "Pisanosaurus" as a heterodontosaurid at one time, but this animal is now known to be a more basal ornithischian.