Sauropods are a subgroup of the saurischian ("lizard-hipped") dinosaurs. Sauropods may well be regarded as the most amazing tetrapods that ever existed. Among them were the largest dinosaurs to ever live. Their early relatives were the Plateosaurs or Prosauropods of the late Triassic. The Prosauropods branched off to give rise to both the Sauropods and the Theropods. These huge quadrupedal herbivores exhibited a fairly simple body structure which varied only slightly throughout the group. (Opposing image courtesy of the University of California Museum of Paleontology).