Paleontologist Jenny Clack thought the textbook story of tetrapod evolution was implausible: How could fishlike creatures, stranded on land, somehow evolve limbs and survive to become the first tetrapods? The search for an answer took her to Greenland, where she found one of the earliest known tetrapods, called Acanthostega. With its fishlike tail and gills, it was certainly adapted to an aquatic environment, but its paddle-shaped fins end in tiny fingers. Vertebrates, it turns out, grew fingers before they left the sea. From Evolution: Great Transformations.