Ancient Species -
Trilobites

Trilobites were the first animals to leave large numbers of fossils. They evolved from sea worms early in the Cambrian Period. (about 570 million years ago). Sea worms, like other earlier creatures, were soft-bodied and, so, did not often create fossils.

Trilobites had three length-wise lobes (hence the name) and a hard shell-like skin-crust which was periodically shed as they grew. They fed on plants and carrion. Trilobites existed, and continued to evolve for about 390 million years, producing vast numbers and enormous variations.

The earliest trilobites had relatively narrow bodies with  a thorax made up of many section, like a multi-jointed worm. Later trilobites evolved with fewer segments, although trilobites with large numbers of segments continued to exist to the end.

Later trilobites also evolved wider, flatter bodies. Some were short and blunt while others had long bodies tapered at both ends. Some developed long projecting spines while others had short spines on their thorax.

The largest animal in the Cambrian Period was a trilobite 18 inches long and weighing about 8 pounds. By the late Ordovician Period (535 to 434 million years ago), a species about 30 inches long had evolved.

During the Ordovician Period, molluscs up to 12 feet in length evolved. These preyed on trilobites, causing the smooth-skinned types to die out - leaving only those with defensive spines. These survived until the "great extinction" at the end of the Permian Period (about 250 million years ago).

Trilobite Fossils

 

Trilobite fossils now available (at eBay):

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Trilobite Homotelus Bromidensis Matrix Fossil Criner Hills Oklahoma Ordovician

AU $132.98
End Date: Sunday Sep-22-2019 6:39:48 EST
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TRILOBITE ELDREDGEOPS RANA ROCHESTER SHALE - NIAGRA COUNTY, NEW YORK

AU $102.01
End Date: Saturday Sep-21-2019 9:39:29 EST
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Plastic Trilobite Fossil Lot Replicas

AU $14.77
End Date: Wednesday Sep-18-2019 3:20:14 EST
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Trilobite Olenellus Bristolia Fossil Matrix Latham Shale Cambrian California

AU $36.89
End Date: Tuesday Sep-17-2019 13:54:30 EST
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Education Geology Science Kit Rock Mineral Collection - Trilobite Specimens

AU $25.67
End Date: Monday Sep-16-2019 1:41:11 EST
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COLLECTIBLES Fossils: Trilobites, from around 520 to 250 million years ago

AU $349.99 (0 Bids)
End Date: Saturday Aug-24-2019 16:43:29 EST
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