Early mammals were significant and fast-evolving elements of the terrestrial biota for much of the Mesozoic, and they have played an increasingly important role in studies of paleoecology, faunal turnover, and historical biogeography. This book thoroughly covers all aspects of the anatomy, paleobiology, and systematics of early mammalian groups, in addition to the extant lineages with long history extending back into Mesozoic. Numerous detailed maps and line drawings enhance the text.