From Encyclopedia Jr, free information reference for Kids
Haplocanthosaurus (meaning "One Spined Lizard") was a sauropod dinosaur which closely resembled Cetiosaurus. Both species, H. delfsi and H. priscus, were found in Colorado with missing skulls. Like other sauropods, it ate shoots and leaves off of the tops of cycads and trees. It lived in Kimmeridgian to Tithonian times, 144 to 156 mya, in the Late Jurassic. It was first discovered by a young college student named Edwin Delfs in the Morrison Formation.