Thanks for the great question.

Scientists have learned a lot about the Earth and living things from fossils. As you know, scientists have found fossils of the same species on modern day continents that are thousands of miles apart from each other. For example, fossils of the Lystrosaurus, a dinosaur that lived 250 million years ago, have been found in Antarctica, India, and South Africa.

Finding the same fossil in such different regions of the world suggests that, millions of years ago, those regions of the world were in fact close together as a part of the same landmass. This is powerful evidence for the theory of plate tectonics, which states that the continents sit upon massive plates that slowly move and slide into each other. So, fossils that were once close to each other have slowly drifted apart as the plates continued their slow march across the surface of the Earth.