Two species of trilobite — Phacops (left) and Greenops (right) — found regularly at Penn Dixie.

Trilobites are extinct marine arthropods that dominated the shallow seas of the Paleozoic era. Penn Dixie has two frequently found trilobites: the more common Phacops rana, and the less common Greenops.

True trilobite enthusiasts should check out Penn Dixie’s trilobite gallery. Click on the images to see a larger version with full caption.