Prosauropods is a paralhypetic grouping of sauropodomorphs (unless sauropods are included) that appeared in the Triassic period and died out in the first half of the Jurassic period. They were found on every continent.
Sauropodomorphs, including "prosauropods", generally grew to very large sizes, had long necks and tails, were bipedal, and became the largest animals to ever walk the Earth (If sauropods are included.). "Prosauropods", which preceded the sauropods, were smaller, and walked on two legs. The sauropodomorphs were the dominant terrestrial herbivores throughout much of the Mesozoic Era, from their origins in the mid-Triassic (approximately 230 MYA) until their decline and extinction at the end of the Cretaceous (approximately 66 MYA).
Prosauropds themselves could walk on both two legs and four. Some scientist have suspected that some prosauropods were omnivorous.