Earth History GEOL 2110 The Paleozoic Era 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.
Gondwana Reconstruction by DuToit (1927Correlating the Permo-Triassic GondwanaOrogen
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
Late Paleozoic GondwanaStratigraphy 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 DwykaTillite Glacial Striations Permian Dropstone
Jurassic Basalts Cap Gondwanan SequenceMarking the Break-up Karoo basalts, South Africa Ferrar Dolerite Sills, Antarctica
Glossopteris Flora unique to the Gondwanan Continents Seed fern that liked cool swampy areas compared to the tropical Lycopsids
The Permo-Triassic Reptiles of Gondwana MesosaurA freshwater fish-eating reptile
Paleogeography and Paleoclimate of Pangea Permian ~250 Ma
Paleogeography and Paleoclimate of Pangea Strong Latitudinal Zoning of Climate Tethys Sea Liehl and Shields, 2005, Geology
Paleophytic MesophyticPlant Transition in Mid-Permiandriven by more arid climates Seedless Vascular Spore-bearing Plants (Silurian-mid Permian) Seed-bearing Gymnosperm Plants (mid-Permian – mid-Cretaceous)
Late Paleozoic Land AnimalsArthopods, Amphibians and Anthracosaurs,Oh My! Anthracosaurs Amphibian -Reptile Missing Link
Amniotes Arrive in Mid-CarboniferousThe Evolution of Eggs with Amniotic Membrane leads to Reptiles, Birds and Mammals Dimitrodon Hyolnomus
The Great Permo-Triassic Extinction90-95% of all marine species die out, and land life too • Proposed Causes • - Global cooling due to • Gondwanaglaciation • Reduced marine habitat due • to the creation of Pangea • Extreme climatic changes • Oxygen depletion due to • exposure of coal deposits • Upwelling of CO2 from deep • ocean waters – hypercapnia • Intense outpouring of basalt • in Serbia • NO EVIDENCE OF A METEOR IMPACT AT LEAST!
WEDNESDAY • Mid-term Exam Review • Chapters 8-13