The presence of Mesosaurus fossils tells us that South America, Africa, and Antarctica were once physically connected, forming a large continent. Mesosaurus was a crocodile-like reptile that lived during the early Permian period, and its remains are found solely in South Africa and Eastern South America. If the continents were still in their present positions, it would have been impossible for Mesosaurus to swim across such a large body of ocean as the Atlantic because it was a coastal animal. Therefore, the distribution of Mesosaurus fossils suggests that South America, Africa, and Antarctica were once joined together, which supports the theory of Pangaea, a supercontinent that existed about 300 million years ago.