Sauropods are generally characterized by a short, massive torso on tall, pillar-like legs; an unusually small head on a long neck; a long whip-like tail and a quadrupedal stance. Sauropods walked upon erect limbs much like modern elephants. The longest sauropods grew to lengths of up to 150 feet. Their long necks served the same basic purpose as the long necks of modern giraffes, that is, to reach the better vegetation high atop the trees on which they fed. Their long tails served as a whip-like defense mechanism for any wouldbe predators. It is also thought that they balanced on their tails and hind legs when reaching the highest vegetation. Some sauropods had their nostrils positioned near the top of their tiny heads rather than at the end of their snouts, as is the case with most terrestrial lizards. This feature is thought by many to be an adaptation for an aquatic lifestyle. (Top left image courtesy of Jeff's Dinosaur Art Gallery).