Q: Why are so many South American animals smaller than their counterparts on other continents? —Donald Dorfman | Sacramento, California Smaller animals have an easier time navigating dense ...

Scientists have identified and named over a million animal species, and there are millions more yet to be discovered across Earth's seven continents. But which continent has the most animal species?

similar animals could have lived at the same time on what are now widely separated continents. You probably wouldn't recognize the Earth if you could see it 225 million years ago. Back then ...