There are a bunch of really interesting landscape features and patterns of diversity around us that were formed millions of years ago. It’s easy to forget that, when the first primates emerged around 35 million years ago, you could walk on dry land pretty far into what’s now the Atlantic Ocean.

If you go even farther back to the first land animals, around 400 million years ago, most of what’s now the United States is underwater, but the Coastal Plain is still dry land.

Go back even farther to the time of the first land plants, around 430 million years ago, and the South Atlantic is all dry land again. It’s just nowhere near the rest of what’s now the United States.

Want to explore those historical changes a little more? Check out this interactive website.