Explaining cases of extraordinary evolution is a fascinating challenge for biologists: fascinating because these cases are so improbable, and challenging because they are historical, and thus cannot be replicated in the laboratory. Instead, evidence from indirect sources, including deoxyribonucleic acid (DNA), anatomy, developmental and life histories, and the fossil record, is necessary to explore how some organisms have adapted to radically different modes of life. In the past several years, for example, research has revealed how early birds and whales adapted to volant (capable of flight) and marine ecologies, respectively, via sequential modifications of ancestral traits.