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Cover image: Fossiliferous sediments from bulk samples from the Caribbean have a rich and diverse fauna but are composed mainly of unidentifiable shell fragments, such as those shown here. Powerful ecological information can be extracted by measuring the relative weights of major guilds, such as corals, clams, and snails. Analyzing community structure in this way revealed that over the last 10 million years, the Caribbean coast shifted from clam-dominated to coral-dominated in response to the closure of the Isthmus of Panama. See the article by O'Dea et al. on pages 5501–5506. Image courtesy of Aaron O'Dea.

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March 27, 2007; 104 (13)
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