Back when the dinosaurs first appeared during the Triassic period, the Earth didn't look at all like it does now. There was one huge land mass, or "supercontinent," named Pangaea. Dinosaurs were able to walk across all the land on Earth, because it was all connected.
As the Triassic period ended, Pangaea began to split into two smaller continents, Laurasia and Gondwanaland. These large masses of land drifted slowly on the molten core of the Earth. Dinosaurs on one continent couldn't get to the other continent, because they were now separated by water.
During the Jurassic period, Laurasia and Gondwanaland moved further apart, and shallow seas began appearing on the continents, further separating the dinosaurs of each region.
By the late Cretaceous period, the continents continued to drift, and were near the locations they are today. The result is that every continent of the Earth has been the site of an exciting dinosaur fossil discovery.
