There is another source of food for Chomper that he could pick. Tickle Fuzzies. Though some like the ones in Stranger from the Mysterious Above, others like Tickles are mute. Chomper could probably bring himself to eat the mute ones as he wouldn't understand them.
Also, he can eat fish no doubt. (Spinosaurus and Baryonyx did after all.)
Another thing that so few mention is why Chomper would want to live away from his parents if Red Claw, Screech, and Thud were to no longer pose a threat to him. I mean, if they died, or were driven out of power, then he and Ruby could just go back home.
Now, Ruby could go back home and come back to the Great Valley as an adult no problem. As for Chomper, everyone forgets another thing about carnivores, they, in reality, don't give a rip whether you eat meat or plants, they might still eat you.
Chomper can eat Belly Draggers and Fast Biters which are smaller than his likely adult form. Trust me, there are ways around the Leaf Eater problem.
What is more problematic is how, if he ever came back to the Great Valley as an adult, how the residents would treat him. We know Littlefoot and the others would treat him good and maybe Mama Flyer too (he did save her life) but I can see others like Topps and Mama Iganuadon being wary still. And likely others may join in that didn't before.
And, the biggest problem of them all
isn't even how Leaf Eaters will react to him, it's what he'll do when he wants to get a mate. I mean, what are the odds of him finding a girl who will agree not to hunt Flatteeth? I mean, what if she likes him but cannot get herself to see the Gang of Five as anything other than food?
That situation could put him in a real dilemma, especially if he really loves her. That actually could create
loads of conflicts. I mean, what does poor Chomper do if a Sharptooth he loves is attacking Littlefoot and the only way to intervene personally might mean to attack her? Worse yet, what if Littlefoot is about to harm her? Would he turn on his best friend to save her?
Also, even if he gets a female to go along with him and gets to live in the Great Valley, well, what if his kids don't like Flatteeth as friends?
Of course, another problem would be how Littlefoot would view him as he got older. I mean, what if Littlefoot was considering getting married (likely to Ali as there's no other female longnecks his age in LBT) himself? He might recall how his dad lost his mate.
And, it probably won't help if Chomper looks a little like:
![](http://i566.photobucket.com/albums/ss110/wenguin/Sharptooth.png)