If you think dinosaurs are cool, wait till you learn what covered Earth 430 million years ago. That's long before dinos even existed. There wasn't much on land-some really tiny plants and even smaller animals like millipedes and mites. But offshore life was another story. Six-foot-long relatives of modern scorpions roamed the open water, gobbling up smaller creatures. Fish were out there, too. There just weren't many of them, and they were much different than today's fish. For one thing, they didn't have jaws. But they were the first animals to have backbones. Eventually they crawled out of the water on primitive feet-and the rest is history!