Trilobites are one of the most successful Paleozoic groups. Because of their diversity and continued evolution they are one of the better groups for time zonation.
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Perenopsids are a group of small blind trilobites. This specimen is actually less than 1.5 cm long (about 1/2 in.) |
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Others were much larger. This trilobite is some 20cm (~8 in.) in length. |
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This is a detail of the trilobite above. Note that the trilobites had already evolved compound eyes, still used today by their relatives, the insects. |
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Others developed bizarre and ornate horns. |
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This is Phacops rana a common North American trilobite. |
Information provided by: http://inst.santafe.cc.fl.us