Wegener proposed that the organisms had lived side by side, but that the lands had moved apart after they were dead and fossilized.
As a continent moves toward the equator, its climate becomes warmer. As a continent moves toward the poles, its climate becomes colder.
Wegener noticed the same thing and proposed that the continents were once compressed into a single protocontinent which he called Pangaea, and over time they have drifted apart into their current distribution.
Pangaea began to break apart about 200 million years ago