The Evolutionary Biology of Extinct and Extant Organisms offers a thorough and detailed narration of the journey of biological evolution and its major transitional links to the biological world, which began with paleontological exploration of extinct organisms and now carries on with reviews of phylogenomic footprint reviews of extant, living fossils. This book moves through the defining evolutionary stepping stones starting with the evolutionary changes in prokaryotic, aquatic organisms over 4 billion years ago to the emergence of the modern human species in Earth’s Anthropocene. The book begins with an overview of the processes of evolutionary fitness, the epicenter of the principles of evolutionary biology. Whether through natural or experimental occurrence, evolutionary fitness has been found to be the cardinal instance of evolutionary links in an organism between its ancestral and contemporary states. The book then goes on to detail evolutionary trails and lineages of groups of organisms including mammalians, reptilians, and various fish. The final section of the book provides a look back at the evolutionary journey of "nonliving" or extinct organisms, versus the modern-day transition to "living" or extant organisms. The Evolutionary Biology of Extinct and Extant Organisms is the ideal resource for any researcher or advanced student in evolutionary studies, ranging from evolutionary biology to general life sciences.