How well can we reconstruct the appearance, movements and behavior of extinct vertebrates from studies of their bones and other, more rarely preserved parts? Where is the boundary between the scientific evidence for reconstruction and the need to resort to imagination? In this book, sixteen paleontologists and biologists discuss these questions, review the current status of functional studies of extinct vertebrates in the context of similar work on living animals, and present a broad philosophical view of the subject’s development within the framework of phylogenetic analysis. The authors describe and debate methods for making robust inferences of function in fossil vertebrates, and present examples where we may be confident that our reconstructions are both detailed and accurate. The detailed studies are placed in the context of their contribution to the understanding of evolutionary processes and will be valuable reading for vertebrate paleontologists, comparative anatomists and evolutionary biologists.