Audio File   THE LAST GREAT MAMMALIAN MIGRATION This is the period of preglacial land elevation in North America, Europe, and Asia. The land was greatly altered in topography. Mountain ranges were born, streams changed [More]
Audio File THE AGE OF ADVANCED MAMMALS This period was characterized by the further and rapid evolution of placental mammals, the more progressive forms of mammalian life developing during these times. Although the early placental [More]