In the film, it is explained that the dinosaurs were genetically altered in a way that prevents them from making lysine, the theory being that without the lysine supplements provided by the park staff, the dinosaurs would die if they ever left the island.

However, most vertebrates, dinosaurs included, do not make lysine within their own bodies anyways (it is an essential amino acid), it must be ingested. Therefore, these dinosaurs could very easily survive outside the park as long as they kept eating.