If the same organisms appears on two different continents, this is evidence of

if the same organisms appears on two different continents, this is evidence of  continental drifting

Explanation:

The theory of continental drifting talks about the movement of the continent on the earths surface relative to one another. Back in the 1900's the continents was recognize to fit like a pieces of picture . They found similarity between the edge of Atlantic coastline of Africa and south America . They recognize the two continents almost fit in together. This brought about the idea that the continents was one(Pangaea) before earth events caused the natural drifting of the continent to form various continents like the South America, Africa, India , Antarctica and Australia.

The fossil records and same organism found in different continent provided more evidence to back the theory of continental drifting. Alfred Wegener was the first to notice the similarity in organism or fossil across different continents and gave the idea that the continents is drifting.  He saw the same fossils at the coastline of Africa and south America continents  . This provided evidence that Continents was one and after drifting of this continents the organisms were scattered to different part of the continents.