Earth History GEOL 2110

The Paleozoic EraPart 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 PangeaConvergence of Laurasia and Gondwanaland

Wegner’s Pangea (1927)

Gondwana Reconstruction by DuToit (1927Correlating 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 tillitesMade it difficult to correlate with European strata based on marine fossilsCapped by Jurassic-Cretaceous basalts – Break-up

Late Paleozoic Glaciation of GondwanaCarboniferousDwyka Tillite

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

Liked cool swampy areas compared to the tropical Lycopsids

The Permo-Triassic Reptiles of GondwanaMesosaur

A freshwater fish-eating reptile

Paleogeography and Paleoclimate of Pangea

Permian ~250 Ma

Paleogeography and Paleoclimate of Pangea

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 AnimalsArthopods, Amphibians and Anthracosaurs, Oh My!

AnthracosaursAmphibian -Reptile Missing Link

Amniotes Arrive in Mid-CarboniferousThe Evolution of Eggs with Amniotic Membrane leads to Reptiles, Birds and

Mammals

Hyolnomus

Dimitrodon

The Great Permo-Triassic Extinction90-95% 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 CO2 from deep ocean waters – hypercapnia- Intense outpouring of basalt in SerbiaNO EVIDENCE OF A METEOR IMPACT AT LEAST!

Summary of Late Paleozoic Biologic and Geologic Events

FRIDAY

Mid-term on Chapters 8-13

25% Multiple Choice from QuizzesFocus on Figures and Figure Captions

Chapter SummariesPowerPoints