When a Billion Years Disappeared (S04E12)

S04E01 That Time the Mediterranean Sea Disappeared S04E02 The Neanderthals That Taught Us About Humanity S04E03 The Giant Dinosaur That Was Missing a Body S04E04 How South America Made the Marsupials S04E05 A Short Tale About Diplodocus' Long Neck S04E06 When the Rainforests Collapsed S04E07 How a Hot Planet Created the World's Biggest Snake S04E08 When the Sahara Was Green S04E09 When Penguins Went From The Sky To The Sea S04E10 How the Egg Came First S04E11 How Dogs (Eventually) Became Our Best Friends S04E12 When a Billion Years Disappeared S04E13 The Risky Paleo Diets of Our Ancestors S04E14 How the Andes Mountains Might Have Killed a Bunch of Whales S04E15 How Plants Caused the First Mass Extinction S04E16 The Two Viruses That We’ve Had For Millions of Years S04E17 How We Identified One of Earth’s Earliest Animals S04E18 When Dinosaur Look-Alikes Ruled the Earth S04E19 The World Before Plate Tectonics S04E20 When Dinosaurs Chilled in the Arctic S04E21 How the Walrus Got Its Tusks S04E22 The Story of the Dino Stampede S04E23 The Biggest Frog that Ever Lived S04E24 The Dinosaur Who Was Buried at Sea S04E25 How We Figured Out Fermentation S04E26 The Oddest Couple in the Fossil Record S04E27 How Ancient Art Captured Australian Megafauna S04E28 The Sea Monster from the Andes S04E29 When Rodents Had Horns S04E30 The First and Last North American Primates S04E31 How Plants Became Carnivores S04E32 How Ankylosaurs Got Their Clubs S04E33 Why Do Things Keep Evolving Into Crabs? S04E34 How Plankton Created A Bizarre Giant of the Seas S04E35 The Rise and Fall of the Tallest Mammal to Walk the Earth S04E36 How Humans Lost Their Fur S04E37 When Lizards Took Over the World S04E38 When the Earth Suddenly Stopped Warming S04E39 The Triassic Reptile With "Two Faces"