Spinosaurus is a massive theropod dinosaur featured prominently in the film 'Jurassic Park III.' Acting as one of the primary antagonists, the Spinosaurus is notable for its crocodile-like snout and distinctive sail on its back. Unlike previous Jurassic Park films that focused on the Tyrannosaurus rex as the top predator, Spinosaurus takes center stage, displaying unmatched ferocity and agility, and even defeating a T. rex in a memorable scene. The creature's unpredictable nature adds tension and danger throughout the story.