I actually like this idea, and I wish it would be done more often.

However, I have to say that you have to be -very- careful about doing this, since you want to make sue the Dinosaurs are in the right areas they'd be in, (A Desert Dino Being found in the Jungle is a pet-peeve of mine), and you either want to have it be like this: Dinosaurs are VERY well known and are used like livestock, (Obviously you'd need small ones for that...) Or they are in areas untouched by the rest of the world. Ancient valleys, craters, plateaus, islands, mesas... Things that are hard, if not impossible, for people to get to.