"Sugiyamasaurus" (meaning "Sugiyama lizard") is the informal name given to an as yet undescribed genus of dinosaur known only from a few spatulate teeth. It was a sauropod, possibly a camarasaurid, which lived in Japan during the Late Cretaceous. The name was first printed by David Lambert in 1990 in the Dinosaur Data Book, and also appears in Lambert's Ultimate Dinosaur Book and in many on-line lists of dinosaurs. Since it has not been formally described, "Sugiyamasaurus" is a nomen nudum. Its remains were found near Katsuyama City.