Without going off on a tangent, there is a huge difference between our pets and dinosaurs. That difference is love. I've been taught that (again more preachy stuff) through God's love that all can be conquered and that love is God's reason for our existence in the first place. He would never deny us that love.

Also I believe God's version of Heaven did exist on earth as Eden. Plenty of animals lived in Eden, so why woulden't there be again?