 Tyrannosaurus was named by Henry Fairfield Osborn in 1905 , along with the family Tyrannosauridae . The name is derived from the Ancient Greek words <unk> / tyrannos ( ' tyrant ' ) and σαυρος / sauros ( ' lizard ' ) . The very common suffix -idae is normally appended to zoological family names and is derived from the Greek suffix <unk> / <unk> , which indicates a plural noun . 
