1
The History of Early Mesozoic Reef Communities: A Three-
Step Process
The History of Early Mesozoic Reef Communities: A Three-
Step Process
Stanely Jr., George D
Palaios (1988) 3:170-183
Stanely Jr., George D
Palaios (1988) 3:170-183
Evolution of Modern Reef CommunitiesEvolution of Modern Reef Communities
Permian Reef CommunitiesPermian Reef Communities
• Sponges• Byzoans• Tubiphytes• Algae• Tabulate Corals• Rugose “Horn” Corals
• Sponges• Byzoans• Tubiphytes• Algae• Tabulate Corals• Rugose “Horn” Corals
Permian-Triassic ExtinctionPermian-Triassic Extinction
Permian HoldoversPermian Holdovers Permian HoldoversPermian Holdovers
2
Middle Triassic Reef CommunitiesMiddle Triassic Reef Communities• Identical to Permian Reefs
• Scleractinian Corals– Competitively weak– Asymbiotic
• Identical to Permian Reefs
• Scleractinian Corals– Competitively weak– Asymbiotic
Karnian-Norian ExtinctionKarnian-Norian Extinction
Symbiosis
Triassic-Jurassic ExtinctionTriassic-Jurassic Extinction Triassic-Jurassic ExtinctionTriassic-Jurassic Extinction
• Loss of competitive species enabled coral dominance
• Quick adaptive radiation of corals (21-100 genera)
• Leads to modern reefs
• Loss of competitive species enabled coral dominance
• Quick adaptive radiation of corals (21-100 genera)
• Leads to modern reefs
ConclusionsConclusions
• Middle-Triassic and Permian reefs near identical (unique among mass extinctions)
• Minor extinction event/evolution of symbiosis led to dominance of Scleractinia
• Major extinction event followed by rapid coral diversification and reef building
• Extinctions important in structuring biological communities
• Middle-Triassic and Permian reefs near identical (unique among mass extinctions)
• Minor extinction event/evolution of symbiosis led to dominance of Scleractinia
• Major extinction event followed by rapid coral diversification and reef building
• Extinctions important in structuring biological communities
Paleoceanography of the coral reefs in the Hawaiian-Emporer
Chain- revisited
Paleoceanography of the coral reefs in the Hawaiian-Emporer
Chain- revisited
Grigg, R. W.
Coral Reefs (1997) 16:S33-S38
Grigg, R. W.
Coral Reefs (1997) 16:S33-S38
3
Evolution of Hawaii-Emperor chainEvolution of Hawaii-Emperor chain Elevation and ageElevation and age
Atoll FormationAtoll Formation Fringe reefsFringe reefs
• Youngest fringe reefs on 100 year old volcanic foundations on Hawaii
• Can form in 100-1000 years
• Youngest fringe reefs on 100 year old volcanic foundations on Hawaii
• Can form in 100-1000 years
Barrier ReefsBarrier Reefs
• Found on outer part of Oahu (2.5Ma)• Found on outer part of Oahu (2.5Ma)
AtollsAtolls
• French Frigate Shoals (11.7 Ma)• French Frigate Shoals (11.7 Ma)
4
Coral growth and latitudeCoral growth and latitude BiogeographyBiogeography
• Oldest colony ~35Ma• Oldest Seamount ~70Ma
– Biogeographic barriers prevented Hawaiian chain colonization
• Oldest colony ~35Ma• Oldest Seamount ~70Ma
– Biogeographic barriers prevented Hawaiian chain colonization
ConclusionConclusion
• 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
• 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
