Where to find trilobites

Frequently asked questions

Where can I find trilobites?

The best accessible trilobite sites vary by continent. In the US, U-Dig Fossils in Millard County, Utah works the Middle Cambrian Wheeler Shale (approximately 507 Ma), where Elrathia kingi is the most common species and complete specimens are yours to keep. Penn Dixie Fossil Park in Hamburg, New York exposes Devonian Hamilton Group shales with Phacops rana and Eldredgeops, alongside brachiopods. Caesar Creek State Park in Ohio produces Ordovician trilobites from the Army Corps spillway section at no cost. In the UK, Wren's Nest Hill in Dudley (Silurian, SSSI) produces Calymene blumenbachii, the Dudley Bug made famous by the local fossil trade. Morocco's Devonian quarries near Erfoud and Rissani produce spectacular, if often restored, Phacops, Drotops, and Hollardops specimens from commercial quarry access.

How do I identify a trilobite?

Trilobites have a three-lobed body plan that gives them their name: a raised central axial lobe runs from head to tail, flanked by pleural lobes on either side. Front to back, the body divides into three sections: the cephalon (head shield), the thorax (flexible segmented middle section), and the pygidium (tail plate). Eyes, when preserved, appear as kidney-shaped or crescent-shaped structures of closely packed facets near the front of the cephalon. Most field finds are isolated parts rather than complete animals, as the exoskeleton disarticulates quickly after death. Enrolled specimens, where the animal curled into a ball like a woodlouse, are a distinctive find. The exoskeleton surface is smooth and faceted with clear bilateral symmetry, unlike the irregular texture of most pebbles.

What geological period are trilobites from?

Trilobites existed from the Cambrian through the Permian, roughly 521 to 252 million years ago — a span of approximately 270 million years. They first appeared in the Early Cambrian as part of the Cambrian Explosion and reached peak diversity during the Ordovician and Devonian. Over 22,000 described species are known, making trilobites one of the most successful animal groups in the fossil record. The entire group went extinct in the end-Permian mass extinction, the largest extinction event in Earth's history, which eliminated an estimated 90 to 96 percent of all marine species. Because different trilobite species have short, well-documented stratigraphic ranges, they are widely used as index fossils for dating Paleozoic rocks — a method called biostratigraphy.