Pure land before time, no magic, no super powers, nothing of that sort.
As it is, the goal is to make a herd as it would appear in the movie. I'm not sure if mixed herds would appear there, but if you really wanted a herd consisting of different kinds of dinosaurs, that is okay with me.
And a plot... well, one will take shape in time, but at first, it will be sort of just a series of events, guided by the motivations of a herd of dinosaurs.