1.) What exactly happens when a Sharptooth gets the prey. (i.e. the gory details)
2.) While we want to have the Gang of Seven die of old age if they have to die at some point (and can't be made immortal), it's unpleasant to think about them in their final days, falling apart, starving, weak, miserable. (I hope that they all just snuff it at the same time if they have to go of old age and don't suffer like we've seen as people get older here in our time and some of their last moments.) (I brought this up as I read a LBT fanfic that kind was like this, with Ducky the last to go, and she was almost senile near the end and finally went away in her sleep. I'm still in therapy from reading that.) Honestly, actually SEEING them die that way, if they don't just die, is worse than seeing them die in a Sharptooth attack or natural disaster, as at least it would be over quickly. (Actually, ironically enough, this option, number 2, is the one I LEAST want to think about and always assume that the animal characters in stories all die peacefully at the same time and so don't have to bury loved ones or die toothless or starving or delirious or whatnot as that's too painful to think of. Maybe I'm overly sensitive. Heck, I'd rather see Chomper kill and eat the Gang of Five and Ruby or Litltlefoot kill Chomper, two things I'd never really want to see, BEFORE I saw option 2 above. Heck, I'd WANT option 4 below to happen if they aren't gonna go peacefully and about the same time. To see them suffer that way in their last days is more than I can bear to even think of.

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3.) What Chomper, even if, as I hope, he never comes to eating Leaf Eaters again (LBT V hinted that he may have at one point), what he might have to go through, knowing that for every meal he gets, something else is gonna die. (One may wonder if he envies the Gang of Five as they never have to go through with it and also envies Ruby as she doesn't have to, even if she does eat fish at times.) Some Sharpteeth might not give a care, but his personality seems that yes, he would care. (He can go to eating other Sharpteeth so he doesn't have to eat Leaf Eaters, which is a very real possibility to avoid what we all dread, but still, the pain that would cause him too would be hard for him.)
4.) What if dino extinction happens during the lifetime of the Gang of Seven.
5.) The idea that one of the Gang of Seven might actually die before the series finale is over.
You can add other things that are too unpleasant in the LBT world to really think about or imagine.