About encroachment by local farmers, I thought that was already happening?
It's been close to 20 years since I saw the movie, but I remember the American scientist got word that some locals had killed one of the dinosaurs, eaten it, and were now sick. She came to investigate and that's how the dinos were found.
Big-game hunters and poachers--now that'd be a problem. The government of Congo, Cameroon, or wherever the movie actually took place would need to deploy a small army with shoot-to-kill authority to deter the horde of would-be dino-killers that would descend on the region in hopes of having an Apatosaurus head over their wet bar or selling dino parts to the Far East in hopes of making them into food items.
(No offense to Hendryk or other Sinophiles, but IIRC tiger penis soup is one reason tigers are an endangered species. An outright dinosaur would be even more tempting, particularly since people used to EAT fossils because they thought they were dragon bones.)