Earth History GEOL 2110 The Paleozoic Era Part 5b: Geological History of Gondwanaland and Late Paleozoic Life

Major Concepts The continental reconstructions of Gondwana by Werner and DuToit were bang on and confirmed by geologic mapping, paleomagnetism, biostratigraphy, and paleogeography. The supercontinent of Gondwana, composed of South America, Africa, Australia, India, and Antarctica, was together for most of the Paleozoic and situated in the high latitudes of the southern hemisphere. Floral and faunal assemblages of Gondwana were very distinct from the northern landmasses (Laurasia) The Permo-Triassic extinction devastated marine life and to a lesser extent, land-based plants and animals. The cause of this greatest of all extinctions is still unclear.

Events of the Late Paleozoic Era

Making Pangea Convergence of Laurasia and Gondwanaland

Wegner’s Pangea (1927)

Gondwana Reconstruction by DuToit (1927 Correlating the Permo-Triassic Gondwana Orogen

Paleomagnetism Confirms Gondwana Continent Reconstructions From Bullard, 1965 Apparent Polar Wander Paths for SA and Africa Best-fit of curves imply that SA, Africa & Australia (& Antarctica) have been together near the South Pole since late Cambrian

Current Reconstruction

Late Paleozoic Gondwana Stratigraphy Dominated by non-marine sediments and tillites Made it difficult to correlate with European strata based on marine fossils Capped by Jurassic-Cretaceous basalts – Break-up

Late Paleozoic Glaciation of Gondwana Carboniferous Dwyka Tillite Glacial Striations Permian Dropstone

Jurassic Basalts Cap Gondwanan Sequence Marking the Break-up Karoo basalts, South Africa Ferrar Dolerite Sills, Antarctica

Glossopteris Flora unique to the Gondwanan Continents Liked cool swampy areas compared to the tropical Lycopsids

The Permo-Triassic Reptiles of Gondwana Mesosaur A freshwater fish- eating reptile

Paleogeography and Paleoclimate of Pangea Permian ~250 Ma

Paleogeography and Paleoclimate of Pangea

Liehl and Shields, 2005, Geology Strong Latitudinal Zoning of Climate Tethys Sea

Paleophytic  Mesophytic Plant Transition in Mid-Permian driven by more arid climates Seedless Vascular Spore-bearing Plants (Silurian-mid Permian) Seed-bearing Gymnosperm Plants (mid-Permian – mid-Cretaceous)

Late Paleozoic Land Animals Arthopods, Amphibians and Anthracosaurs, Oh My! Anthracosaurs Amphibian -Reptile Missing Link

Amniotes Arrive in Mid-Carboniferous The Evolution of Eggs with Amniotic Membrane leads to Reptiles, Birds and Mammals Hyolnomus Dimitrodon

The Great Permo-Triassic Extinction 90-95% of all marine species die out, and land life too Proposed Causes - Global cooling due to Gondwana glaciation - Reduced marine habitat due to the creation of Pangea - Extreme climatic changes - Oxygen depletion due to exposure of coal deposits - Upwelling of CO 2 from deep ocean waters – hypercapnia - Intense outpouring of basalt in Serbia NO EVIDENCE OF A METEOR IMPACT AT LEAST!

Summary of Late Paleozoic Biologic and Geologic Events

FRIDAY Mid-term on Chapters % Multiple Choice from Quizzes Focus on Figures and Figure Captions Chapter Summaries PowerPoints