This book is not intended to give a full and comprehensive account of the Mesozoic mammals, and nor is it intended as a handbook for research workers studying pre-Tertiary mammals. Our intention is to give an account of the origin and evolution of certain of the characters of the Mammalia. We have tried to portray the fossils we describe as the living animals they once were, not as dead bones. Our account ends with the end of the Lower Cretaceous, since by that time the major characters of the mammals had become established. There exist a number of characters which, at the present day, are confined to the Mammalia. These include: (1) a jaw articulation formed by the squamosal and the dentary; (2) a chain of three bones, malleus, incus and stapes connecting the tympanic membrane to the inner ear; (3) the presence of hair or fur; (4) the presence of milk-glands in the female; (5) the left aortic arch is the systemic arch; (6) the phalangeal formula in both manus and pes is 2.3.3.3.3; (7) some of the teeth have more than one root. Of these characters (1) or (2) are sufficient by themselves to define a mammal; characters (6) and (7) are known to have been already in existence in some of the mammal-like reptiles - the ancestors of the mammals.

There are nearly 6,000 mammalian species, among them our own. Research on our evolutionary cousins has a long history, but the last 20 years have seen particularly rapid progress in disentangling the interrelationships and evolutionary history of mammals. The present volume combines up-to-date reviews on mammalian phylogenetics with paleontological, taxonomic and evolutionary chapters and also summarizes the historical development of our insights in mammalian relationships, and thus our own place in the Tree of Life. Our book places the present biodiversity crisis in context, with one in four mammal species threatened by extinction, and reviews the distribution and conservation of mammalian diversity across the globe. This volume is the introductory tome to the new Mammalia series of the Handbook of Zoology and will be essential reading for mammalogists, zoologists and conservationists alike.

“Mesozoic mammal fossils are the focus of this fascinating book, which reviews both the fossils themselves and the history of their discovery.” —Choice In Pursuit of Early Mammals presents the history of the mammals that lived during the Mesozoic era, the time when dinosaurs ruled the Earth, and describes their origins, anatomy, systematics, paleobiology, and distribution. It also tells the story of the author, a world-renowned specialist on these animals, and the other prominent paleontologists who have studied them. Zofia Kielan-Jaworowska was the first woman to lead large-scale paleontological expeditions, including eight to the Gobi Desert in Mongolia, which brought back important collections of dinosaur, early mammal, and other fossils. She shares the difficulties and pleasures encountered in finding rare fossils and describes the changing views on early mammals made possible by these discoveries. “A thorough review of the current state of early mammalian paleontology presented through the unique historical filter of someone who was at the foremost of the field for over half a century.” —The Quarterly Review of Biology “Whether she’s talking about how mammals evolved their distinctive ear bones, or how she built a cabin out of plywood during a particularly cold field season in the Gobi, you know that a remarkable, passionate person is telling a story of science and adventure in her own words.” —Priscum “A fascinating window into the development of the field . . . The perspective of an individual at the center of these developments is captivating, informative, and has never before been published.” —Gregory P. Wilson, University of Washington