The dinosaurs existed in three different periods: Triassic, Jurassic, and Cretaceous. However, all the dinosaurs, as well as other prehistoric animals who appeared in this movie did not all exist in the same period. Triceratops, Parasaurolophus, Pachycephalosaurus, Tyrannosaurus, and Pteranodon were Cretaceous animals, while Apatosaurus (called Brontosaurus here) and Stegosaurus were Jurassic dinosaurs. Meanwhile, Dimetrodon, erroneously portrayed with a snake-like tongue, was actually a mammal-like reptile that lived way before the dinosaurs, more than 100 million years before this movie takes place. See more
Once upon this same earth, beneath this same sun, long before you, before the ape and the elephant, as well; before the wolf, the bison, the whale, before the mammoth and the mastodon, in the time of the dinosaurs. Now the dinosaurs were of two kinds. Some had flat teeth, and ate the leaves of trees, and some had sharp teeth for eating meat, and they preyed upon the leaf-eaters. Then it happened that the trees began to die. The mighty beasts who appeared to rule the earth, were, in...