This second, completely revised edition of "Paleogene fossil birds" gives a comprehensive, updated overview of the avian fossil record from a geological period that lasted from the end-Cretaceous mass extinction event (66 million years ago) to the end of the Oligocene epoch (23 mya). Paleogene avifaunas are highly diversified and not only feature unusual archaic groups without close living relatives but also offer unique insights into the evolution and biogeographic history of extant birds. The main body of the book constitutes an in-depth survey of the known diversity of Paleogene avifaunas. The reader is introduced into basic skeletal features of extinct avian taxa, with these fossil forms being placed into a phylogenetic context in the light of current hypotheses on the interrelationships of extant birds. The geographical and temporal occurrences of the various fossil groups are outlined and their evolutionary significance is discussed. Concluding sections inform more general aspects of Paleogene avifaunas, such as possible causes of major faunal changes. In addition to being a reference work for the early evolution of modern birds from a paleornithological perspective, the present work also enables researchers in other fields of vertebrate paleontology to gain an improved understanding of Paleogene ecosystems. Numerous color photos of representative specimens furthermore make the new edition attractive to a wider audience interested in the avian fossil record.