The roots of this book reach back to my graduate student years when I was quite proud of myself for the discovery of what I mistakenly believed was the first Asiatic marsupial among the undescribed treasures of the American Museum of Natural History. That it turned out to be a didymoconid placental is immaterial, because after that all fossil marsupials had a special meaning for me for a complex of reasons. Simply put, their morphological diversity, constrained so differently from what one was accustomed to in placentals, coupled with the many unknown aspects of their history, had a great appeal. It seemed that fossil marsupials could provide one with additional perspectives on evolutionary morphology beyond what placentals could offer. It was also the subsequent realization in the 1970s that postcranial remains in the fossil collections of major museums were waiting, so to speak, to be incorporated into a synthesis of metatherian evolution.

More than any other support, a Fellowship from the John Simon Guggenheim Foundation enabled my family and me to spend time in South America where I could study fossil marsupials, and a sabbatical year in 1980 perusing the extinct and extant marsupials in Australia. A number of grants from the City University of New York have provided support for the countless tasks that seem to be without end when a larger project is brought to fruition.