Rex is a tiny tadpole who can"t wait to grow up and be big like everybody else. Unfortunately for Rex, he lives in a prehistoric swamp . . . and everybody else is a gigantic dinosaur.            With a little time--and a lot of patience--Rex does grow, gaining arms and legs and, most importantly, a personality big enough to take on even the mightiest of his neighbors.             Includes a note from the author about metamorphosis, prehistoric frogs, and the environmental challenges frogs face today.