<*R.* at least hasn't been illustrated in dorsal view.>
[...] However, Mark Hallett illustrated the dorsal view of *R. krausei* in the original Curry-Rogers & Forster paper. You can see this image here:
http://www.palaeos.com/Vertebrates/Units/Unit330/Images/Rapetosaurus2.gif
Oopsie. Yes, that's the pic I saw just the day before. :-]
<...were outside the question, which was "what happens when a *Brachiosaurus* trips".>
We were also discussing titanosaurs.
Elephants seem fully capable of laying down as adults and getting up again, from their sides.