How did flying birds evolve from running dinosaurs, terrestrial trotting tetrapods evolve from swimming fish, and whales return to swim in the sea? These are some of the great transformations in the 500-million-year history of vertebrate life. And with the aid of new techniques and approaches across a range of fields--work spanning multiple levels of biological organization from DNA sequences to organs and the physiology and ecology of whole organisms--we are now beginning to unravel the confounding evolutionary mysteries contained in the structure, genes, and fossil record of every living...