Sauropodomorpha is an extinct clade of saurischian dinosaurs that includes the long-necked, herbivorous sauropods and their ancestral relatives. Early, more basal sauropodomorphs were bipedal, and the earliest show evidence of omnivorous or carnivorous diets. Over time, sauropodomorph evolution resulted in a shift to herbivorous diets, larger body sizes, and quadrupedal locomotion. The sauropods themselves generally grew to very large sizes, had long necks and tails, and became the largest animals to ever walk the Earth. The sauropods were the dominant terrestrial herbivores throughout much of the Mesozoic Era, from their origins in the Late Triassic until their decline and extinction at the end of the Cretaceous.