In the present book the Paleogene fossil record of birds is detailed for
the first time on a worldwide scale. I have developed the idea for such
a project for several years, and think that it is an appropriate moment
to present a summary of our c- rent knowledge of the early evolution of
modern birds. Meanwhile not only is there a confusing diversity of
fossil taxa, but also significant progress has been made concerning an
understanding of the higher-level phylogeny of extant birds. Hypotheses
which were not considered even a decade ago are now well supported by
independent analyses of different data. In several cases these group
together morphologically very different avian groups and allow a better
understanding of the mosaic character distribution found in Paleogene
fossil birds. The book aims at bringing some of this information
together, and many of the following data are based on first-hand
examination of fossil specimens.