Well... Ruby may be larger than Chomper, but it is hard to see how she could keep him safe... she has no teeth, no ability to really fight, and her only defense is running away...
Just because an animal doesn’t have teeth doesn’t mean it can’t bite. Trust me; a scarlet macaw nipped me on the forearm once. It wasn’t much more than an annoyed pinch, and the fact that I was wearing a long-sleeved shirt meant that the bite didn’t even pierce the skin, and yet I still had a substantial bruise on that arm for at least two weeks afterwards (I didn’t hold it against the macaw, though

). And while I can’t imagine a bite from Ruby would do much against a large sharptooth (though, for that matter, neither would one from Chomper), I have considerable respect for the jaw strength of any dinosaur that can pulverize a clam into a swallowable mouthful in about eight bites without the aid of teeth.

P.S. I am working on a
mammoth post (more of a thesis, really) detailing my theories about Ruby, her home, family, species, and mission, that I will be posting here sometime in the near future (provided it doesn’t end up needing its own thread). Just thought I’d get this out of the way first.
