According to National Geographic, sea floor spreading and plate tectonics indicate that the continents do move or shift, which supports continental drift theory. Fossils of the Mesosaurus, an ancient freshwater reptile found in the southern parts of South America and Africa, also indicate that the two continents could have once been one solid continent that drifted apart, since the reptile could not have swum across the ocean.
Continental drift is a theory originally proposed by Alfred Wegener, who believed the continents were once one large continent known as Pangaea that later separated into several continents. One indication of this possibility is the appearance of the western African and eastern South American coasts, which look like two interlocking jigsaw puzzle pieces. Finding fossils of the Mesosaurus on the southern hemispheres of both continents is a further indication that the two continents were once together and later drifted apart.
Another indication of continental drift is tectonic activity and seafloor spreading. Scientists agree that continents rest on rocks called tectonic plates, which shift and move. Sea floor spreading further supports the continental drift theory. As molten rock rises from the Earth, it forms new crust between the plates. When this occurs, the sea floor grows wider, pushing the two continents apart. Sea floor spreading indicates that since the continents presently move apart, previous continental drift was possible and probable as well.