Problem: Significant mass extinctions occurred during which of the following periods? Need Assignment Help? Multiple Choice Triassic, Permian, Cretaceous, Pleistocene, Ordovician, and Devonian Triassic, Permian, and Cretaceous Pleistocene, Ordovician, and Triassic Ordovician, Triassic, and Jurassic Ordovician, Triassic, Jurassic, Silurian, Eocene, and Oligocene