603-pp19 - The History of Early Mesozoic Reef Communities A...

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Unformatted text preview: The History of Early Mesozoic Reef Communities: A ThreeStep Process Stanely Jr., George D Palaios (1988) 3:170-183 Evolution of Modern Reef Communities Permian Reef Communities Sponges Byzoans Tubiphytes Algae Tabulate Corals Rugose "Horn" Corals Permian-Triassic Extinction Permian Holdovers Permian Holdovers 1 Middle Triassic Reef Communities Identical to Permian Reefs Scleractinian Corals Competitively weak Asymbiotic Karnian-Norian Extinction Symbiosis Triassic-Jurassic Extinction Triassic-Jurassic Extinction Loss of competitive species enabled coral dominance Quick adaptive radiation of corals (21-100 genera) Leads to modern reefs Conclusions Middle-Triassic and Permian reefs near Minor extinction event/evolution of identical (unique among mass extinctions) symbiosis led to dominance of Scleractinia Paleoceanography of the coral reefs in the Hawaiian-Emporer Chain- revisited Grigg, R. W. Coral Reefs (1997) 16:S33-S38 Major extinction event followed by rapid coral diversification and reef building Extinctions important in structuring biological communities 2 Evolution of Hawaii-Emperor chain Elevation and age Atoll Formation Fringe reefs Youngest fringe reefs on 100 year old volcanic foundations on Hawaii Can form in 1001000 years Barrier Reefs Found on outer part of Oahu (2.5Ma) Atolls French Frigate Shoals (11.7 Ma) 3 Coral growth and latitude Biogeography Oldest colony ~35Ma Oldest Seamount ~70Ma Biogeographic barriers prevented Hawaiian chain colonization Conclusion Hawaiian-Emperor chain is an excellent model for paleoceanography studies Coral reefs can only survive as long as accreation > bioerosion/subsidence/transgression Lifespan of 28 million years 4 ...
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