It's interesting that even in the years after Jurassic Park III, when Jurassic Park 4 failed to materialise, no Hollywood studio tried to make a dinosaur movie. The closest thing we got was King Kong, and that doesn't count because the dinosaurs weren't the focus of the movie and just happened to be there. I wonder if studios saw the downward trend in box office returns for the Jurassic Park trilogy and figured that franchise (dinosaur) fatigue was setting in.