The aim of this book is to examine a variety of problems in the understanding of the evolutionary history of the marsupials. In his exposition, the author covers developmental and reproductive biology, the cranio-skeletal system (including dentition, skull, and postcranial morphology), and the ecologically related aspects of skeletal morphology. In reviewing the evidence from bones, he presents much new information on both living and fossil groups of marsupials. All groups of marsupials are treated in detail, and in the final chapter their history in space and time and their paleobiogeography are considered.