Continental Drift and Paleogeography Overview

Sep 6, 2024

Lecture Notes: Continental Drift and Paleogeography

Key Topics

  • Continental drift and supercontinent Pangea
  • Paleogeographic maps and climate proxies
  • Species diversity and speciation

Continental Drift and Supercontinent Pangea

  • Pangea: Supercontinent at the Permian-Triassic boundary.
    • Allowed for widespread biogeographic distributions for terrestrial organisms.
    • No barriers for movement across land masses.
  • Mesozoic Era: Gradual breakup of Pangea into modern continents.
    • By the Cretaceous-Paleogene boundary, continents resembled modern positions.

Paleogeographic Maps

  • Depict land elevations and ocean depths.
    • Land: green and brown shades.
    • Oceans: light to dark blue shades.
  • Continental Breakup: Driven by rifting that forms oceans between continents.
  • Sea Levels: High sea levels can lead to continental flooding and shallow seas on top of continental crust.

Climate Proxies and Sedimentary Records

  • Climate Bands: Different sedimentary deposits indicate various climates.
    • Coal deposits in warm, wet environments.
    • Evaporites and paleosols in dry, arid environments.
    • Glacial till and striations indicate glacial presence.
  • Fossil Proxies: Use of fossilized plants and minerals to infer past climates.

Species Diversity and Speciation

  • Species-Area Effect: Larger areas tend to support more species.
  • Climate Impact: Climate and environment influence biodiversity.
  • Fragmentation Impact: Fragmentation of land masses leads to speciation.
    • Isolation of populations results in unique evolutionary paths.
  • Diversity Through Mesozoic: Increase in land animal diversity, including dinosaurs, due to changes in climate and landmass configurations.

Changing Continental Positions

  • Mesozoic Era: Distinct changes in climate and geography.
    • Fragmentation from Pangea to smaller continents.
    • Isolation of land masses influenced dinosaur faunas.
  • Geographic Distribution: Shared evolutionary histories within land masses, distinct between separated continents.
    • Example: Distinct dinosaur faunas in northern vs. southern hemispheres.

Paleobiology Database and Future Work

  • Upcoming lab module to use the paleobiology database.
  • Homework includes mapping fossils to recognize past continental positions and their biogeographic impact on dinosaurs.
  • Tutorial video assigned for database familiarity.

This summary captures the main points of the lecture on continental drift, paleogeography, and the biogeographic implications for dinosaurs during the Mesozoic era.