BIO 475 Lecture 13: Paleogeography
The study of geographical features at particular times in the geological past.
All reefs form on antecedent structures
Not all reefs are built by corals
Middle Ordovician 470m.y.a
● Rugosa and Tabulata appear ( ~2.0cm scale)
○ Rugosa
● Corals on reefs, but not major framework builders
Silurian 420m.y.a
● Tabulata decline, rogosa dominant coral
● Reefs abundant and diverse
● Reefs become truly wave-resistant carbonate platforms
Middle Devonian- 370m.y.a
● Reefs at max development for Paleozoic
● Framework builders include microbialites, calcifying cyanobacteria
● Stromatoporoid and other sponges as well as tabulate and rugose coral
Mississippian (Upper Carboniferous ) 340m.y.a
● Reefs rare and in deeper water
● Climatic shifts, sea level fluctuations, low ocean temperatures
●
Pennsylvanian (Lower carboniferous) 300m.y.a
● Reefs still rare, and in deeper water
● Climatic shifts, sea level fluctuations, low ocean temperatures
Early Permian - 280 m.y.a
● Shallow (“would be”) reef areas dominated by algar
● Corals rare
● (getting closer to Pangea)
Late Permian - 260 m.y.a
● Reef-life structures by bryozoans, sponges, algae and tubiphytes
● Corals uncommon
● Permian-Triassic mass extinction 250 m.y.a; “The Great Dying” 80-95% of all species
extinct, including all corals
Middle Triassic - 240m.ya.
● Reef-life structures are built by bryozoans, sponges, algae and tubiphytes
● Scleractinia appear
● Likely start of coral-zooxanthellae symbiosis
Introduction to Scleractinia
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Document Summary
The study of geographical features at particular times in the geological past. Rugosa and tabulata appear ( ~2. 0cm scale) Corals on reefs, but not major framework builders. Stromatoporoid and other sponges as well as tabulate and rugose coral. Reefs still rare, and in deeper water. Climatic shifts, sea level fluctuations, low ocean temperatures. Shallow ( would be ) reef areas dominated by algar. Reef-life structures by bryozoans, sponges, algae and tubiphytes. Permian-triassic mass extinction 250 m. y. a; the great dying 80-95% of all species extinct, including all corals. Reef-life structures are built by bryozoans, sponges, algae and tubiphytes. Hard rayed or stony corals or hexacorals. Not closely related to tabulata or rugosa , probably arose independently. Abundance of massive scleractinian reefs in the tethys sea. End of triassic extinction: collapse of tethys reefs. Reefs rare, coral genera depauperate(lacking in #"s) but diverse. Scleractinian reefs flourish in tethys of europe and mediterranean. Extensive volcanism releases co2 , earth warms.
