New Fossil Birds From The Earliest Eocene Of Mongolia

Understanding of the Asian early Paleogene avifauna is limited relative to that of North American and European avifauna of the same period. While major patterns of mammalian faunal exchange among these three regions across the Paleocene/Eocene boundary have been described, much less is known about the dynamics of bird diversity over the same time interval. Here, we report bird fossils from the earliest Eocene Bumban Member of the Naranbulag Formation in central Mongolia that add to the known record from Asia from just after this boundary. Most of this material, collected by the joint American Museum of Natural History/Mongolia Academy of Sciences expeditions, is referable to a previously described taxon in Presbyornithidae (Anseriformes). However, five isolated elements are identified as comprising at least four species from at least three other major avian clades. While further inclusive phylogenetic analyses of each of these clades are necessary, the new remains represent possible earliest occurrences in Asia of these clades. The material includes a humerus and a furcula from shorebirds (Pan-Charadriiformes), a quadrate from a stem member of the flamingo-grebe lineage (Pan-Mirandornithes), and a coracoid from a stem galliform (Pangalliformes). We also report a humerus with uncertain phylogenetic affinities but with similarities to core Gruiformes. These new fossils expand our knowledge of the Asian avifauna during this time and have the potential to further inform our understanding of the early biogeography of these clades. The shorebird and flamingo-grebe material indicate that both these lineages were present in Asia by the earliest Eocene. The pan-mirandornithine quadrate provides insight into the early feeding ecology of the flamingo-grebe clade.

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.

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.

An exploration of all that is known about the origin of birds and of avian flight. It draws on fossil evidence and studies of the structure and biochemistry of living birds to present knowledge and data on avian evolution and to propose a new model of this evolutionary process.