What were the prosauropods?
The prosauropods (Prosauropoda) were some of the first dinosaurs to be discovered and described in the 1830s, which was even before the term dinosaur was coined to describe these huge reptiles. The name prosauropod, or “precursor of the sauropods,” is a misnomer, as the earliest known creatures were already too specialized to be the ancestors of the sauropods, but the name is still used today.
The prosauropods evolved during the late Triassic period some 230 million years ago, and they apparently disappeared at the end of the Early Jurassic period. Most prosauropods had blunt teeth, long forelimbs, and extremely large claws on the first finger of the forefoot (often called the thumb claw); most were semi-bipedal (walked on two legs). They were mostly herbivores, and only toward the Early Jurassic gained the huge size or special adaptations of the later herbivorous dinosaurs.
It is currently difficult to pin down the classification of the prosauropods. In certain classifications, saurischian dinosaurs were also divided into the suborder Sauropodomorpha, with another division Prosauropoda. Another classification suggests the Sauropodomorpha were divided into the Sauropoda, Prosauropoda, and Segnosauria. Still other classifications just list the prosauropods as an extinct offshoot of the saurischians.