Ever since mysterious bones were found in 1822, scientists and artists have tried to figure out what the creature they came from looked like. But it seems that every time they’ve made up their minds, someone makes a new discovery, and they have to start all over. That’s only fair, though—after all,...

If your species happens to be alive right now, you should feel very lucky. You probably know about the downfall of the dinosaurs and how the dodo bird met its doom. But you might not have heard about the other weird and wonderful creatures throughout the eons that just didn’t make it. But that...