Vertebrates are the most familiar of all animals on Earth, with humans being but one of about 45,000 species of living vertebrates. The rise of the first vertebrates is synonymous with the Paleozoic Era, a span of increasing ecological complexity where the first explosion of life occurred in the seas. In this fully illustrated volume, ""The First Vertebrates"" examines the dramatic rise of vertebrate life in the Paleozoic seas with the development of early fish, including jawless fish, fish with teeth and jaws, early sharks and other cartilaginous fish, and bony fish, the ancestors of present-day fish species.