Sharks are among Earths oldest creatures. They appeared at least 420 million years agothats 200 million years before the first dinosaurs! These organisms were quite different than the ferocious marine predators we know today. Readers will love learning about these aquatic animals and how scientists think they survived against vicious marine reptiles such as pliosaurs. This books lively design, along with its high-interest topic, makes it a must-read for shark and dinosaur lovers.