Contents -- Figures and Tables -- Acknowledgments -- Introduction -- Part 1: What Is a Bird? -- 1 The Bird beneath the Feathers: How adaptations for flight allow a bird to earn a living on the ground -- 2 A Bird Is an Animal with Hollow Bones: Special features of avian bones and their assembly as a skeleton -- 3 A Bird Is Like a Dinosaur: Features shared by birds and their reptilian ancestors -- 4 A Bird Is Not So Like a Dinosaur: Features that distinguish birds from their reptilian ancestors -- Part 2: What Kind of Bird Is It? -- 5 The Kinds of Birds: Classification and taxonomy -- 6 That Bird Is Different from the Other One: Evolutionary relationships among families of birds -- Part 3: How Does a Bird Fly? -- 7 Feathers and Feathered Dinosaurs: Flight in early birds and birdlike animals -- 8 Birds with a Modern Shape: Birds cease to look like feathered dinosaurs and become skilled fliers -- 9 Birds on Land: A robust design helps birds compete with mammals -- 10 Birds at Sea: Sophisticated aerodynamics take birds onto oceans -- Conclusion -- Appendices -- 1 Birds in Relation to Other Vertebrate Animals -- 2 Geological Time Scale -- Glossary of Ornithological Terms -- A -- B -- C -- D -- E -- F -- G -- H -- I -- J -- K -- L -- M -- N -- O -- P -- Q -- R -- S -- T -- V -- W -- Y -- Literature Cited -- Index -- A -- B -- C -- D -- E -- F -- G -- H -- I -- J -- K -- L -- M -- N -- O -- P -- Q -- R -- S -- T -- U -- V -- W -- X -- Y -- Z.