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Unraveling the Past: Paleobiogeography Explained

Explore the study of fossil organisms' geographic distributions and how they reflect ancient ocean water masses, tectonic processes, and climate changes. Learn how plate distributions can explain organism distributions and predict climate shifts.

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Unraveling the Past: Paleobiogeography Explained

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  1. Paleobiogeography

  2. What is it? • Studying geographic distributions of fossil organisms • So what? • Biostratigraphy – correlating between biotic provinces • Paleogeography – tracking sea level changes, reconstructing plates and continents • Paleoclimatology – using organisms to track climate

  3. Water Masses • “Bodies of ocean water with relatively uniform conditions of temperature and salinity • E.g.: California Current, Central Pacific Water

  4. http://oceanmotion.org/html/background/timeline1978-88.htm

  5. Implications: • Geographic distributions of organisms can reflect boundaries of water masses • Equatorial currents act as dispersal barriers to marine organisms (cold water critters can’t cross equator) • Ocean currents depend on: • Continental positions • Heat budget of Earth • And so does the geographic distribution of organisms • So mapping the organisms can map ancient ocean water masses and currents

  6. Tectonic processes affect the distribution of organisms • Creation/elimination of dispersal barriers • E.g. Opening of Atlantic is barrier to land organisms, pathway for marine organisms • Changes in ocean currents • Changes in basin depth & therefore sea level • Changes in climate – continentality promotes extreme terrestrial climates

  7. Implications • Plate distributions can explain organism distributions • E.g., Tethys organisms • Organisms can be evidence for plate reconstructions

  8. Examples • Gondwana reconstructions • Mesosaurus – freshwater lizard • Glosspteris – tropical flora • “Viking funeral ships” – dead when the continents separated

  9. http://www.mrsciguy.com/sciimages/fossil_record.gif

  10. Examples • Gondwana reconstructions • Mesosaurus – freshwater lizard • Glosspteris – tropical flora • “Viking funeral ships” – dead when the continents separated • Baja rifting • Legless worm lizard • “Noah’s ark” – range separated while species was extant

  11. Examples • Exotic terranes: • Late Paleozoic to Meoszoic California (and the ret of the Cordillera) is made of many accreted terranes – • As small as island arcs from subduction zones • As large as continental fragments • Evidence • Lithologic • Paleomagnetic – magnetic declination & inclination • Fossils – tropical fusilinids in Permian rocks

  12. http://plate-tectonic.narod.ru/terranesswamerphotoalbum.html

  13. Organisms & Climate • Distribution of organisms is affected by climate & climate change • If you know the biology, you can infer the climate: pollen • If you know the climate (using other evidence – isotopes, pollen), you can infer biology: high latitude dinosaurs & homeothermy • Maybe we can use past climate & biogeographic shifts to predict the current change • What happened in interglacials? Where to the climate & vegetation belts go?

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