Here's why:

* Wide Distribution: Glossopteris fossils have been found on continents now widely separated, including South America, Africa, India, Australia, and Antarctica.

* Similar Species: The fossils found on these continents are remarkably similar, suggesting they all originated from the same ancestral plant species.

* Climate Evidence: Glossopteris fossils indicate a climate that was temperate and moist. This is significant because the continents where these fossils are found now have vastly different climates.

The presence of Glossopteris on such widely separated continents, alongside other evidence like matching geological formations, was a crucial piece of the puzzle in supporting the theory of continental drift and the formation of the supercontinent Pangea.