General Information

Trilobites belong to the phylum of Arthropods and the class of Trilobita. Their closest ancestors known to trilobites today have been traced to spiders and horseshoe crabs. They roamed the world in the seas during the Paleozoic era, but were extinct before the dinosaurs got there. We are able to garner a good amount of information on these organisms because of how easily fossilizable they are relatively due to their hard exoskeleton, made of calcite and calcium phosphate. The trilobite had three main parts: the cephalon (head), thorax, and a pygdium (tail). The name, trilobite, meaning three lobes doesn’t actually refer to these three parts, but refers to a long central axial lobe with two pleural lobes to the left and to the right.

Why they’re cool and why they matter?

The oldest eyes known were traced to trilobites. Their diversity is astounding with about 22,000 species identified. This diversity and the incremental change of trilobites through time provide a excellent information on adaptation to environment changes and how these changes altered the evolutionary history of the trilobites. Furthermore, their prevalence and ability to be fossilized rather easily make trilobites excellent index fossils when examining and dating rock strata that they are found in.


Works Cited
Arenillas, Ignacio. “Trilobites.” Encyclopedia of Time: Science, Philosophy, Theology, & Culture (n.d.): n. pag. Web.
Hughes, Nigel C., and H. B. Whittington. “Trilobites.” Palaios 8.4 (1993): 396. Web.

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