AP Photo

When we think about the history of life on earth and the vast changes that have transpired over millions and millions of years—as single-celled organisms evolved into species as disparate as redwood trees, dragonflies and humans—are wonderfully apparent. But, among all that evolutionary change, some organisms have little modified from their distant ancestors. Creatures such as sharks and crocodiles are often viewed as evolutionary sluggards or “living fossils.” While the rest of nature was caught up in life’s race, the coelacanth and duck-billed platypus sat things out.