In 1877, Professor Othniel Charles Marsh had noted that the name "Megadactylus" had been preoccupied by "Megadactylus" Fitzinger 1843, a subgenus of the lizard genus "Stellio". In 1882, he replaced the name with "Amphisaurus", "near saurian", probably referring to Marsh's interpretation of it as intermediate between primitive dinosaurs — at the time the British "Palaeosaurus" was an example of what was thought to be a primitive dinosaur — and more derived dinosaurs. In 1885, Marsh had discovered that this name also had been preoccupied, by the athracosaurian "Amphisaurus" Barkas 1870, and again replaced it by "Anchisaurus", with the same meaning.