In this episode of Talk Nerdy, Cara speaks with Smithsonian National Museum of Natural History paleobiologist and Curator of Fossil Marine Mammals Dr. Nick Pyenson about his new book, "Spying on Whales: The Past, Present, and Future of Earth's Most Awesome Creatures." They talk about the similarities between cetaceans and land-dwelling mammals, along with what makes them unique among Earth's creatures (extinct and extant).