Why do some coastlines look like parts of jigsaw puzzles?

The map of the world has many coastlines that look like pieces of a jigsaw puzzle separated by stretches of blue ocean water. One of the most noticeable pair of jigsaw partners border the Atlantic Ocean. The west coast of the Americas looks as if it would fit neatly into the eastern coastlines of Europe and Africa.

We cannot, as yet, prove the past history of earths land masses, but some experts suggest that the continents were once a single land mass. The original land mass may have cracked and separated, which could account for some of the jigsaw coastlines. There are other facts which support this theory, but we cannot say for sure that this is the explanation.