Paleobiogeography

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

Water Masses

• “Bodies of ocean water with relatively uniform conditions of temperature and salinity

• E.g.: California Current, Central Pacific Water

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

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

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

Implications

• Plate distributions can explain organism distributions– E.g., Tethys organisms

• Organisms can be evidence for plate reconstructions

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

separated

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

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

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

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

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?