Actually, from what I heard about the fourth film, it will have nothing to do with the Pterodons that we see flying away at the end of III. They are going to go a different direction with the franchise.
In my opinion, Jurassic Park III was almost as good as the first film, and tons better then the second one. That whole Godzilla type ending to the second film was complete crap. The third movie fits much better in with the events of the first.
MTFBWY and HH!!
Jar Jar Binks