After the extinction event at the end of the Cretaceous Period, only a small number of species survived into the Cenozoic Era. Among those were small mammals who evolved to dominate life on land, including one species called homo sapiens—human beings. Engaging images and informative graphics help explain the development of life on Earth through the Cenozoic Era, while an encyclopedic-entry-style format makes the text approachable and highly browsable. Final comprehension questions encourage reflection on what readers have learned.