It's been mentioned before. The villains are leaf-eaters. Which is interesting, because previously, all of the villains (aside from Hyp and his gang being...well, kinda like villains, but really just bullies) are, of course, sharpteeth. Villains that the characters can talk and interact with are fun, no doubt about it. We get a little glimpse into what their motives are, and why they do the things they do. It's not just some hungry carnivore that Littlefoot and the others have to run away from or "defeat" by tricking. Not that this lessens the others - each sequel has something unique about it. But villains among your own lot are interesting. XD
I'm not sure what you're talking about. Other than Pterano, I don't recall there being any leaf-eater villains in the 7th movie.