Susan Ewing’s nonfiction writing digs into the quirkier side of nature—the odd beasts, fun factoids, and wondrous workings of the natural world. Her latest book, "Resurrecting the Shark: A Scientific Obsession and the Mavericks Who Solved the Mystery of a 270-Million-Year-Old Fossil," is about a very ancient, very unusual creature, Helicoprion, that had a spiral of teeth imbedded like a pizza cutter in the middle of its lower jaw.