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an order of dinosaurs. Saurischians are characterized by a triradiate pelvic girdle, a feature of most reptiles, which distinguishes them from the ornithischians. They lived from the middle of the Triassic period to the end of the Cretaceous period. They are grouped into two suborders on the basis of their structure and way of life: the predatory bipedal Theropoda and the herbivorous Sauropoda. Saurischians were widely distributed throughout the planet.