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Unformatted text preview: trilobites - dominate Cambrian record "Patterns" in metazoan groups - radiation, persistence through time, decline in diversity to "living fossil" status or final extinction correspondence to evolutionary faunas (times of maximum diversity) background extinction (normal times) mass extinctions (unusual events) - 5 medium-to-large events during Phanerozoic in marine environment; physical perturbation (several causes) + collapse of ecosystems; most at period or era boundaries (why?) Back to Outline Main page...
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- Spring '08