Imprints of the Past

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Trilobites, Ammonites, and Belemnites

Trilobites' jointed legs identify them as members of the phylum Arthropoda, one of the most successful of all animal groups. They were also among the first animals to possess segmented outer skeletons.

The combination of these physical features gave trilobites distinct advantages in mobility, feeding, and self-protection. They evolved into more than 10,000 species and dominated the seas for 20 million years. About 510 million years ago, trilobites went into sharp decline and finally became extinct about 250 million years ago.



[Trilobite in shale]
Trilobite in Shale		 [Trilobite]
Trilobite		 [Crinoids]
Fossil Crinoids
[Ammonite]
Fossil Ammonite		 [Belemnites]
Belemnites


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