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Why do similar fossils occur on continents separated by the Atlantic Ocean?

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Watch Earth's Continents Move — paleogeography Watch a time-lapse of Earth changing through geologic time, from the Cambrian Era to the projected period of Pangea Proxima.

The presence of similar fossils on continents separated by the Atlantic Ocean is a key piece of evidence for the theory of continental drift and the existence of the supercontinent Pangea.412

Rather than these continents having always been separated, paleogeographic evidence indicates that they were once joined together as part of larger landmasses, such as Gondwana or Pangea. During the time these organisms lived, they were able to inhabit continuous environments across these connected landmasses.341

As the supercontinent fragmented and the continents drifted apart—a process driven by plate tectonics—the fossil-bearing rock layers were carried to their current, widely separated locations. Consequently, finding identical fossils, such as those of the genus Lystrosaurus, on different continents confirms that these landmasses were once physically connected, allowing for the distribution of these species across what are now vast oceanic basins.3451