Well, it definitley seems to be a phenomenon that denies in-universe exlanation...
Though there's nothing wrong with talking antagonists; random sharpteeth popping up all over the place is starting to seriously get old...
What type of animal do you guys think would create an ideal antagonist?
Bothtooth, without a doubt. The omnivore who could eat Leaf Eater food and speak Leaf Eater language but also would secretly be thirsty for some blood.
Also, another nice antagonist idea would be whoever may have been responsible for wiping out most of Littlefoot's herd before the first film began. It could be a very evil Sharptooth or even a wicked Leaf Eater who just wanted the Longnecks dead so he could have more of the dwindling green food out there for himself.
Also, if I didn't love him too much, Chomper himself would make the most ideal antagonist as
1.) He knows Leaf Eater.
2.) He has shown himself capable of cornering prey as he's done it in both films II and V. (In fact, he's the only Sharptooth I think that really had the entire Gang of Five cornered and expecting to die all at one time. Other Sharpteeth might have cornered some members of the Gang of Five but not all of them at once.)
3.) He knows the layout of the Great Valley (few Sharpteeth can boast of that)
4.) He could well have the Gang's scent.
5.) The Gang of Five trusts him and he easily use that for sinister purposes if he wanted to to make a nice big meal.
6.) He appears to be pretty bright, although naive.
7.) His abilities when he is older would make him a threat to the Gang of Five, particularly if his abilities matched that of the villain from the first movie.
As for Dil and Ichy talking, I hope they meet Chomper someday. I'd love to hear what conversations they'd have.
As for my Bothtooth villain idea, as others are on this rabbit trail already, he'd pose as a Leaf Eater, misdirect most of them, and then use Sharptooth minions to get any stragglers and enjoy some of the meat.
He'd have been responsible for the death of Littlefoot's mother, would kill the leader of Tippy's herd, and also be responsible for the death of the Old One. He'd also try and murder Ruby and Ali. The villain would be especially evil as, though he probably didn't intend it, he got Littlefoot banished for life from the Great Valley and had put Chomper in a bind where he had to kill the Old One to save his lover from being killed by the Old One. Littlefoot had helped some grownups from apprehending Chomper, and hence got banished for helping, as most believed, a murderous and treacherous Sharptooth escape justice.
The villain would send out assassins to try and whack Littlefoot, Chomper, and Chomper's girlfriend Andromeda.
Eventually, the Gang of Seven and their dates would all find out the villain's true leanings, with Chomper and Andromeda being the first to catch on sometime before all the others. However, they'd all escape from him and then the villain, having found that the Great Valley was awoken by Chomper's girlfriend, would try and say she was lying about him being bad and then would say that she and Chomper were plotting to murder the Great Valley and that the Gang of Five and their dates, plus Ruby, had joined forces with them and then demand that he be allowed to execute the heroes for "high treason".
Also, the villain would be a huge speciest, though secretly he'd hate all kinds except Bothteeth. He'd also be going around trying to keep Leaf Eater herds from being too friendly, preaching speceism and posing at various times as both a Sharptooth and a Flattooth. He'd also be causing similar stuff among the Egg Stealers.
Eventually, he'd apply his tactics to the Great Valley and get the herds to stop being the Combined Herd and now be various feuding bickering herds and this speceism would even pull Ali, Cera, Ducky, Petrie, and Spike apart as they'd bicker too.
