Figure 2 Reefbuilding Episodes over 500 million years

^^^scleractinian a rudist-ML scleractinian

a scleractinian-calcisponge i_i

A algal-calcisponge-^^ tubiphyte

climax phases t:>:-::-:::-i pioneering - arrested phases ■■I extinction phases

Source: Copper, Paul. "Ecological Succession in Phanerozoic Reef Ecosystems: Is It Real?" Palaios 3: 136-152, fig. 4, p. 147. (Reprinted with permission)

Note: Some authors claim that these patterns in the fossil record are examples of succession. Clearly, the largest patterns of evolution and extinction are reflected in the waxing and waning of reefs at this scale of resolution, not the local processes involved in succession.

a scleractinian-calcisponge i_i

A algal-calcisponge-^^ tubiphyte

larger, more inclusive systems. Some have gone even further and described major transitional patterns at the provincial to global scale as instances of succession, such as the waxing and waning of reef-building episodes in marine environments through the Phanero-zoic Eon (see Figure 2). Reefs disappear during mass extinctions and eventually reappear during intervening periods, consisting of generally similar "guilds" (functional groups) but of different taxonomic components. Other workers have referred to such patterns as "community evolution," occurring over time spans of 1,000,000 to 100,000,000 years. Clearly, the processes involved in these major transitions in the history of life are completely different from succession occurring in a local ecosystem. Recklessly using the terminology in this way has not only caused confusion but has also retarded efforts (especially in paleontology) to understand the true nature of evolutionary and ecologic processes occurring at such grand scales. Some of these very large transitions have occurred only once (the emergence and deployment of complex marine ecosystems at the beginning of the Cambrian Period), while others appear to reflect recurrent ecologic patterns involving different kinds of organisms and probably different causes (for example, mass extinctions in the Phanero-zoic Eon, all of which seem to include extinction, survival, and recovery phases; see Mass Extinction).

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