Although, if Chomper could learn to swim and hunt for fish/other aquatic creatures, perhaps this could be a happy end for all. 
Let’s not forget, Pterosaurs and other flying dinosaurs could visit the island if they so desire, also landing occasional food for Chomper on the deserted island.
So hypothetically, all hope is not lost. 
Indeed, all hope is not lost...except for Mo and Pterano.
This statement does not sit well with me, especially when you say Mo. Indeed, his species in real life does technically qualify him as a Sharptooth, but the relationship between him and his Mud Brothers would remain relatively unchanged. There is no threat here and no danger to the Gang. Although, I’d imagine they would be shocked at this revelation at first.

...
Oooh...now I see what you mean. Alright, carry on. I retract my statement.

I wonder if Chomper wpuld adopt a new name if he gave in to making a meal of the Gang? Afterall Littlefoot named him, so after making friends food, Chonper may want a new name. 
I have no ideas at the moment.

But surely that’ll never happen...right?
