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Unformatted text preview: Date : September 1, 2007 When Bivalves Ruled The World Science Daily Before the worst mass extinction of life in Earth's history -- 252 million years ago -- ocean life was diverse and clam-like organisms called brachiopods dominated. After the calamity, when little else existed, a different kind of clam-like organism, called a bivalve, took over. Margaret Fraiser, UW-Milwaukee assistant professor of geosciences, shows fossils of the few survivors of the Permian-Triassic mass extinction, the most severe in Earth's history. (Credit: Alan Magayne-Roshak, UW-Milwaukee) What can the separate fates of these two invertebrates tell scientists about surviving an extinction event? A lot, says UWM paleoecologist Margaret Fraiser. Her research into this particular issue not only answers the question; it also supports a relatively new theory for the cause of the massive extinctions that occurred as the Permian period ended and the Triassic period began: toxic oceans created by too much atmospheric carbon dioxide (C0 2 ). The theory is important because it could help scientists predict what would happen in the oceans during a modern "C0 2 event." And it could give them an idea of what recovery time would be. Studying the recovering ecology is equally significant, says Fraiser. The evolution of surviving species in the aftermath of the mass extinction set the stage for Studying the recovering ecology is equally significant, says Fraiser....
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