The Evolution of Feathers - From their Origin to the Present

Abstract

Birds, the last living dinosaurs, have fascinated humans since ancient times, primarily due to their ability to fly and their colourful appearance. Both characteristics are closely related to their unique epidermal integument, the feather, which represents the morphologically most complex and diverse skin derivate within vertebrates. Due to their high diversity in shape that varies between different body regions, feathers can fulfil a large number of biological roles, including flight, body insulation, display and sensory func- tion. But how did this aberrant integumentary structure evolve, and what was its initial biological role? With the discovery of the famous Urvogel Archaeopteryx in the lithographic limestones of southern Germany just two years after the publication of the Darwin’s seminal book The Origin ofSpecies, it became evident that the presence of modern feather types, including flight feathers, extended back to at least the Upper Jurassic, preceding the origin of toothless beaks, clawless hands with fused fingers or a strongly reduced tail. For decades, it was considered to be common sense that the origin of feathers was primarily driven by the evolution of flight, using Archaeopteryx as key witness from the fossil record. Since the description of Sinosauropteryx from the Early Cretaceous of China in 1998, numerous new discoveries of non-avian dinosaurs covered with various types of feathers have challenged this idea fundamentally and led to new evolutionary scenarios for the origin of feathers, their changing functional significance and a new understanding of dinosaurs in general. This book is devoted to the origin and evolution of feathers and highlights the crucial impact of palaeontology on this field of research, documenting the successive increase of morphological complexity along the line towards modern birds. However, this book would not have been possible without the help ofmany colleagues and friends who need to be acknowledged. First, we thank Verena Penning for inviting us to edit a book on the evolution of feather. Lars Körner and Rajeswari Balachandran are thanked for their patience and editorial support during the production of this book. We further thank all authors for their contributions as well as Richard Butler, Tom Holtz, Jingmai O’Connor, Michael Pittman and Randall Widelitz for their careful reviews. Finally, the senior editor, Christian Foth, would like to thank Ragnar Kinzelbach and Stefan Richter for their contemplative mentoring during his studies at the University of Rostock, when he started exploring the fascinating world of feathers.