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When did trilobites live, and when did they become extinct?
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arthropod
Spiny lobster, or rock lobster (Palinurus elephas).
Trilobites were a group of marine arthropods that first appeared approximately 521 million years ago, near the beginning of the Cambrian Period. While they were highly successful and dominated the seas during the Cambrian, their abundance declined in subsequent geologic periods.1
Trilobites persisted until the end of the Permian Period (298.9 million to 251.9 million years ago), when they became extinct during the massive Permian-Triassic extinction event.12