This series explores how the process of evolution resulted in the animals we know today. Each book examines a major group of animals, with titles on amphibians, birds, fish, insects, mammals, and reptiles. The books trace the evolutionary history of these groupings as far back as possible, examining not only what we know but how we know it. Aligned to Common Core Standards and correlated to state standards. Essential Library is an imprint of Abdo Publishing, a division of ABDO.