I have a hard time imagining sauropods submerging themselves in *anything*. Sucking breath through those long necks would have been hard enough at the best of times. Having additional pressure around the lungs wouldn't have improved things. Of course, just because I can't imagine something doesn't mean it didn't happen. :-)
Mud is one thing, but water... the more pneumatic sauropods floated like corks, as I'm sure we all remember. :-)
Another reason I think it unlikely that sauropods *prefered* swampy areas has to do with cost verses benefits. Sauropods had tiny mouths for their size, which would have restricted the amount they could eat per unit of time. This in turn would suggest metabolisms considerably lower than those found in other dinosaur lineages.
Absolutely not. Elephants chew -- sauropods didn't. Yes, *Camarasaurus* has precise tooth occlusion, but its jaws are like two pairs of serrated hedge scissors; there's no grinding going on whatsoever, it just took smaller bites.
The only remaining big question is how sauropods prevented their gut contents from going mouldy. Elephants have extra-broad guts to _shorten_ the passage time.
I imagine (there's that word again) that plowing through mud would require much more energy than walking up sloping ground (depending of course on the degree of slope). Would sauropods have been able to spare all that extra energy? Perhaps if it meant the difference between immediate life-or-death, but somehow I don't see them pushing their way through swamps (or even deep water) on a regular basis.
Agreed.