Paleontologists noticed that fossils of the same species were found on different continents, even though they were separated by oceans. This observation was a key piece of evidence supporting the theory of continental drift and later plate tectonics.

For example, the discovery of identical fossils of the ancient reptile *Mesosaurus* in both South America and Africa was a strong indicator that these continents were once connected. Similarly, the presence of similar fossil plant species on continents now separated by vast oceans supported the idea of past land connections.