PALEOZOIC ERA Period Permian Period— (split into Mississippian & Pennsylvanian Periods in the United States) Carboniferous Period Devonian Period Silurian Period Ordovician Period Cambrian Youngest Oldest MESOZOIC ERA Period Cretaceous Period Jurassic Period Triassic Youngest Oldest
PALEOZOIC ERA Permian Period Carboniferous Period— (split into Mississippian & Pennsylvanian Periods in the United States) Devonian Period Silurian Period Ordovician Period Cambrian Period Youngest Oldest MESOZOIC ERA Cretaceous Period Jurassic Period Triassic Period Youngest Oldest