ABSTRACT
BACKGROUND: THE CENOZOIC ERA The end of the Cretaceous Period, which was also the end of the Mesozoic Era, was marked by a mass extinction event which saw the end of the dinosaurs and pterosaurs on land, and ammonites and marine reptiles in the sea (Chapter 10). In the succeeding Cenozoic Era, which consists of the Paleogene, Neogene (together these are commonly referred to as the Tertiary), and Quaternary periods, animals and plants assumed a more modern appearance. Mammals and birds replaced dinosaurs and pterosaurs as the dominant vertebrates on land. After the Cretaceous Period, the numerous ecological niches left empty by the extinction of the dinosaurs quickly became filled by mammals and birds in an adaptive radiation. By the middle of the Eocene Epoch (the middle epoch of the Paleogene Period), nearly all of the orders of mammals and major groups of birds had evolved, and there were also present some mammal groups that have since become extinct. At this time there were no high Alps, nor North Atlantic, and Europe and North America were still connected by land bridges in the vicinity of the Faroes.
