Here is a rare example of an Proetid Trilobite from the Permian age of Kansas.
The order Proetida is the last surviving trilobite order at the end of the Palaeozoic epoch.
The Trilobites where quite even rare before they completely extinct, at mass extinction event on the end of the Permian age.
This even was quite even imported like event at the end of the Cretaceous age that was responsible for extinction of Dinosaurs.

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