An archeologist and his helicopter pilot crash land in a massive crater in South America where dinosaurs have managed to survive. They are attacked by a Tyrannosaur and the pilot is eaten. We then skip ahead a few years where an American commando squad is sent in to stop a terrorist named Marquez, who has kidnapped a female scientist to get her to develop an airborne virus that can be delivered in a bomb. They manage to rescue the girl and capture the bad guy but their helicopter also crashes into the "Lost World", where they eventually run into the crazy archeologist, who has been living there for nearly a decade.
While there are a few scenes in which the dinos look decent enough, for the most part the CGI and live-action do not blend very well. There's nothing threatening about cartoons attacking people. Also, the movie is poorly written, with cardboard characters, a plot "borrowed" from Irwin Allen's version of The Lost World. Worst of all, the fact that they crash among dinosaurs are an afterthought. The soldiers readily kill a dozen of them even though in the end the survivors wish to keep this forgotten land a secret? Why--to preserve the dinosaurs? They killed off almost all of them! What a dumb movie.