The cerebral cortex is the crowning achievement of evolution and the biological substrate of human mental capacities. Using a comparative evolutionary developmental approach to the study of its origin helps to offer new insights into this complex and important problem. The comparison of immature stages reveals features of evolution that are otherwise obstructed by the complexity of the mature brain, and the analysis of development in terms of possible evolutionary events helps us to focus on the most biologically relevant mechanisms. In this book, leading experts in the fields of mammalian, reptilian, avian and amphibian brain development and from evolutionary biology, tackle the fundamental question of the origin of the cerebral cortex. The book includes critical examinations of methods used to study homology in the central nervous system and methods used in cladistic analysis. Recent data on the earliest generated transient cells in the mammalian, reptilian, avian and amphibian forebrain are discussed, as are possible homologies based on specific connectional analysis. The various hypotheses on the origin of the mammalian isocortex are discussed in detail and new results are presented on cortical organization in reptiles, birds, marsupials, monotremes and other species.