When did life on earth begin? and What killed the dinosaurs? are some of the tricky questions answered in this new addition to a popular series. With its unique mix of realistic illustration and engaging cartoons I Wonder Why Fish Grew Legs will amaze, amuse, and inspire, while the highly visual format encourages kids to keep reading.,Realistic illustrations and charming cartoons combine to reveal the mysteries behind such inquires as when did life on earth begin and what killed the dinosaurs, in an innovative reference that satisfies any child's curiosity about the prehistoric world.,Questions and answers discuss the origins of life, the development of land animals, the rise and fall of the dinosaurs, the coming of mammals, and the first humans.When did life on earth begin? and What killed the dinosaurs? are some of the tricky questions answered in this new addition to a popular series. With its unique mix of realistic illustration and engaging cartoons I Wonder Why Fish Grew Legs will amaze, amuse, and inspire, while the highly visual format encourages kids to keep reading.,Realistic illustrations and charming cartoons combine to reveal the mysteries behind such inquires as when did life on earth begin and what killed the dinosaurs, in an innovative reference that satisfies any child's curiosity about the prehistoric world.,Questions and answers discuss the origins of life, the development of land animals, the rise and fall of the dinosaurs, the coming of mammals, and the first humans.