Complex sentence: For a prosauropod, its neck is rather long and the forelimbs are relatively short, from it had been inferred that the species was bipedal, even before it became common to assume this for all basal sauropodomorphs.
Split into simpler sentences: For a prosauropod, its neck is rather long and the forelimbs are relatively short. From these it was inferred that the species was bipedal, even before it became common to assume this for all basal sauropodomorphs.