Imagine that Dr Alan Grant, having had first hand experience with the T-rex and raptors in JP1 and JP3, evolves from being a paleontologist to being an expert on living dinosaurs, studying them in the wild over the course of the next 20 years (hell maybe INGEN even hired/convinced him to help with their research until they lost control of the islands). Dr Grant grows from being a paleontologist studying fossils to studying the real thing in real life and becoming one of the world’s foremost experts on raptors.
Perhaps with the help of Ellie Sattler, they both pioneer new research into dinosaur behavior biology and osteology, discovering that over this period of time, since the dinosaurs ventured off the islands, Earth’s food chain has become affected with potential dire consequences for humanity. All while their unrequited love grows for one another(Not that you need it)… Here you cross the story over with Claire Dearing and Owen Grady who are tackling the illegal capture and black market trade of Dinosaurs.
There is no need for BIOSYN or INGEN anymore, their story has already been told. The creatures they engineered are loose and the world is left to clean up their mess much like an oil spill, they didn’t mean to cause an ecological disaster but the damage has been done. We can move on from this trope of an evil corporation that has nefarious motives… also why do these multi billion dollar corps seem to always have the worst security systems on the planet… oh right to move the story forward...
Then the the core of the film is introduced. As Dr Grant and Dr Sattler study the Dinosaurs in the wild, they discover that the dinosaurs are affecting the Earth’s food chains. Raptors, T-rex and other dinosauria super-predators are taking out normal food sources of natural habitats affecting other apex predators like wolves and lions meaning that those animals are dying out along with the food chain below them. With natural food sources running out for the carnivore dinos, they start attacking cattle ranches and chicken farms etc. This begins to affect human food production, hell you can even leave in the dumb locust thing destroying crops, but rather than them being engineered and the main focus of the plot, they are just a side product of increased dinosaur population(after all it is a dinosaur centric film). Moving things along perhaps the dinosaur black market trade has introduced them into habitats where the dinos may not have naturally got to, throwing the natural order of things out even more so.
Brachiosaurs and Triceratops and other such sauropods are eating out the food sources of modern day herbivores like elephants and deer, and affecting wider mammalian territories. Perhaps even some of the genetically engineered flora that INGEN produced has made its way across the planet and that too is affecting the eco-sphere of habitats across the planet (Could have been a nice commentary on climate change). Lo and behold Drs Grant and Sattler discover that all these elements are starting to affect the human food chain and something has to be done about it.