If you want to something a bit more unusual, I've got an idea for some more esoteric dinosaurs for you, LOTRfan.
What about these fellas?
Spoiler
Bulbasaur, Ivysaur, Venusaur
I'm thinking they'd be magical beasts, sizes Tiny, Small and Huge, respectively. Pretty tough, probably some kind of obscene reach from their vine whip attacks...