One I can remember off the top of my head was one where the great valley was destroyed (perhaps by meteorite?). Basically, in the aftermath, it ended up looking like the lands from the first film, only worse. I believe a disagreement began, probably between Cera and someone, about what they were to do. Ultimately, they all split up and went their separate ways. Spike clearly knew this was a bad move, but still followed Ducky. Cera spent the rest of the time attempting to scale a chasm or something, like in the first film.
Meanwhile, Littlefoot and his Grandparents walked for a while on a trek that ultimately took them to a small grove by a waterfall/cliff, where a herd of Spiketails and Longnecks lived. All of a sudden, the leader of the Longneck herd (she was a matriarch, full of herself, and she had an adult son who was poncy)came over, greeting the Longnecks, who were "the desired dinosaurs", in her words. It then dawned that the longnecks considered themselves superiour to the silent Spiketails, who only ever ate and were considered idiots (Although you could see that they were smarter). Littlefoot's Grandparents were immediately infuriated with the longnecks and abruptly headed off, following the pathway going through the waterfall/cliff (In my dream, it was like this was a dangerous route, and they weren't paying attention in their anger). Littlefoot stopped for some reason, looking back and when he turned around, his grandparents had vanished.
The dream then jumped forward to his adulthood. I think Littlefoot met up with Bron at some point, and ultimately moved to a truly beautiful valley, where lakes, hills, and shrubs blended. It ended with him standing in the middle of it, wondering where his friends were, and if it had been worth it. (At the start of my dream, I am sure that I was watching the "last film" that would be made).
So yeah, it was kinda depressing.
I also had one where all the characters were walking down a pathway through the bush, and every now and then a path would head off to the side. After heading down one of them, it led them to a river, with a huge cave system that was shaped like a boat, with rooms carved into them. Each path had this, and each one represented each of the films, with the characters there. Unfortunately I don't remember how the rest of that went, although I do remember it got vaguely epic and life-threatening as it went on, although it had a happy ending.
And I also had one (In my dream, it was the Sixth or Seventh film) where Guido and Petrie flew through the air, and Guido crashed near the ruins of some US spaceship, and inadvertantly activated some missiles (I didn't see them, but they were on their way). The GOF were heading there to stop this, but the problem was it was on the other side of a chasm. I don't remember the rest, it may have involved Pterano, but I remember thinking "That was pretty damn good" when the film was over.
