The final version of Jurassic Park: Operation Genesis includes only 25 dinosaur species. However, the development team had originally hoped to include 40 species very early on, with many of them implied to be sea-dwelling and flying creatures. Ultimately, this was whittled down to the 25 dinosaurs seen in the final game due to time constraints, and also the developers wanting to focus on creating fewer, but more interesting dinosaurs, as opposed to a larger number of less interesting dinosaurs. As such, they decided to make the dinosaurs they had count and focus on species that players would recognize from the films.