Well in the movie, I do think that Littlefoot and his friends come across a few things of water. Like the small thing of water Littlefoot found Ducky in, small streams, small puddles, small ponds, and the deep pool at the end of the movie where they push Sharptooth in. I think it might be possible for the Diplocaulus to survive the journey. They might have to tough it out a while without water, but given the fact there's plenty instances of scenes in the movie where we saw water, I think it's safe to say it's possible but it would just be difficult! At any rate I'm really REALLY having troubles deciding which one to use. Maybe I should make a poll and leave it up to fate?