Plateosaurus engelhardti

Plateosaurus means "flat reptile", a name that was long poked fun at in the days of Godzilla-inspired upright postures. Then prosauropods suffered through a "they are all quadrupedal" phase (which I participated in), which still made a mockery of the name, as the position contorted the body so that the tail had to arc up into the air above the body. Well, it turns out that Plateosaurus-grade "prosauropods" used a low-slung subplantigrade bipedal posture instead which makes "flat reptile" not such a bad name after all...

Update: Brought the silhouette up to date. I went with the "fat tail" style contour for the ventral margin (the bottom!) of the tail, as many extant diapsids are like this, and with the low fourth trochanter and high transverse processes Plateosaurus is a prime candidate to have had similarly large caudofemoralis muscles.