The prerequisite to investigating the underlying causes behind mass extinction is a profound understanding of the evolutionary history of both living and dead species. It is especially important to appreciate the significance of such studies in extinct organisms; especially in organisms that were abundant in a certain geologic era, but have subsequently dwindled or become extinct. Such studies should help to accurately evaluate patterns of evolution in extinct species lineages and help predict the same in its modern analogs. The book includescutting edge research in evolutionary biology that should serve as a starting point for conservation.