Sauropods are a suborder of the Dinosauria, a vast group of reptiles that dominated terrestrial environments during the Mesozoic (245 to 66 million years ago). Dinosaurs ("terrible reptiles") are characterized by erect limbs and a pelvis that incorporates at least five vertebrae, characteristics that are related to their active lifestyle. Dinosaurs are divided into two major groups based on the structure of the pelvis. In the Saurischia ("lizardhipped"), the pubis points forward, while in the Ornithischia ("bird-hipped"), the pubis has swung backward to lie parallel to the ischium. The Saurischia includes the carnivorous dinosaurs, or theropods, as well as the herbivorous sauropods ("lizard-foot"), the largest land animals that have ever existed.
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