This text is a comprehensive and illustrated discussion of the origin of birds and of avian flight. Ornithologist and evolutionary biologist Alan Feduccia, author of Age of Birds, here draws on fossil evidence and studies of the structure and biochemistry of living birds to present knowledge and data on avian evolution and propose a model of this evolutionary process. Feduccia begins with an overview of bird evolution, giving his opinions about the controversial problem in verte-brate paleontology: whether birds evolved directly from bipedal, terrestrial dinosaurs (the ground-up theory) or from the precursors of dinosaurs - perhaps small arboreal thecodonts (the trees-down theory). He then provides information about the origin of avian flight and feathers and discusses the most dramatic discoveries in avian paleontolgy of the past few decades - the opposite birds that were the dominant landbirds of the Mesozoic. Feduccia next offers a theory of avian evolution during the Tertiary, arguing that the evolution of birds follows a pattern similar to that of mammals, with an explosive (rather than gradual) evolution lasting only 5 to 10 million years. In the second half of the book he summarizes the evolution of all the modern orders of birds, discussing such subjects as the evolution of filter-feeding in ducks and flamingos, the evolution of flightlessness, the evolution of birds of prey and the rise of landbirds. The book also includes reconstructions of ancient fossil birds that have been prepared by bird artist John O'Neill.