High Quality Content by WIKIPEDIA articles! Haplocanthosaurus (meaning "simple spined lizard") is a genus of sauropod dinosaur. Two species, H. delfsi and H. priscus, are known from incomplete fossil skeletons. It lived during the late Jurassic period (Kimmeridgian - Tithonian stages), 144 to 156 million years ago. The type species is H. priscus, and the referred species H. delfsi was discovered by a young college student named Edwin Delfs in Colorado. Haplocanthosaurus specimens have been found in the very lowest layer of the Morrison Formation, along with Hesperosaurus, Eobrontosaurus, and Allosaurus jimmadensi.