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Re: More on the Massospondylus embryos

Galton & Upchurch (in their Prosauropoda chapter of Dinosauria II) regard Saturnalia and Thecodontosaurus as fully bipedal,
Riojasaurus and the other melanorosaurids (Melanorosaurus, Camelotia, Lessemsaurus), and the remaining prosauropods as facultative
bipeds. They quote Christian and Preuschoft in suggesting that Plateosaurus was a habitual quadruped which may have used a bipedal
gait for its fastest locomotion and while standing.

What I wonder about...

Based on their long torsos and short limbs, most Triassic and Early Jurassic sauropodomorphs look very unconvincing in a bipedal position. (Interestingly *Plateosaurus longiceps* is among the best-looking bipedal runners.) But then came the description of *Antetonitrus* which says more derived sauropods had their forearms fixed in a pronated position, says that *Antetonitrus* could rotate them freely so it could both walk and grasp with its hands, and implies that all more basal sauropodomorphs, like theropods and crocodiles, had their forearms fixed in a supinated position, though it isn't very clear on this. I have trouble imagining walking quadrupedally when the hands point laterally. Did the poor beasts walk on their fists, like anteaters? Or have I missed something...? ~:-S