Fossils are valuable for studying continental drift because they provide evidence of ancient organisms and ecosystems that existed in different parts of the world. When similar or identical fossils are found on continents that are now separated by vast oceans, it suggests that these continents were once connected. This supports the theory of continental drift, which proposes that continents were once part of a single landmass (Pangaea) and have since drifted to their current positions. Fossils offer a tangible link between different regions and help scientists reconstruct the history of Earth's geological changes and the movement of tectonic plates.