Travel back in time to the Ice Age in this installment of the hit nonfiction graphic novel series about prehistoric Earth! After the dinosaurs died out, Earth was by no means empty. There were still some little resourceful critters around who, without big predators to hunt them down, survived and thrived. Who were these scrappy creatures? Early mammals, our ancestors! In the Cenozoic Era, mammals rose to dominance and spread over the globe, resulting in woolly mammoths, saber-toothed tigers, and eventually all of humankind. In this adventure, readers will meet the three kinds of mammals—monotremes, marsupials, and placental mammals—as well as the other amazing ancient beasts they shared the Earth with during the Cenozoic Era. Travel along on this fascinating journey through time, from 66 million years ago to present day. Want more adventures in prehistoric Earth? Check out the other books in the Earth Before Us series: Dinosaur Empire! and Ocean Renegades!