Contents: Ordovician and Cambrian Periods, Devonian and Silurian Periods, Permian, Pennsylvanian, and Mississippian Periods, Jurassic and Triassic Periods, The Cretaceous Period, Evolution of the Horse, Cenozoic Era
Contents: Ordovician and Cambrian Periods, Devonian and Silurian Periods, Permian, Pennsylvanian, and Mississippian Periods, Jurassic and Triassic Periods, The Cretaceous Period, Evolution of the Horse, Cenozoic Era