I know nothing about many things, and the mechanics involved here are definitely one of them. But you're right, that is a key question. Wonder what the sleeping posture was (if any)?
The cartoon I had in mind was sort of a 'squirrel chewing a nut' posture, only w/ the tail flat on the ground. That would place the jaws as high off the ground, or higher, than they would be when walking. Although I have no idea if such is actually feasible.
That would imply the proximal tail bending through closer to 90deg. Surely a tyrannosaur couldn't do that?!
-- Andreas Johansson
Why can't you be a non-conformist just like everybody else?