(Isotelus maximus)

As the scientific name implies, this species of trilobite is among the largest found in the fossil record. Trilobites of this type are commonly found in southeastern Indiana but mostly as partial specimens and fragments. Collectors avidly hunt for small, entire specimens. At approximately six inches long, we rarely find such a sizeable and complete individual. Specimens such as this require the delicate hand of a skilled preparator to free the fragile fossil from the encasing rock.

Although superficially they look like cockroaches and horseshoe crabs, trilobites are only distantly related, but all are part of the Phylum Arthropoda. Paleontologists can make some inferences about trilobite lifestyles even though they are now extinct. Like other arthropods, they shed their exoskeleton several times throughout their life. The vast quantity of trilobite fragments preserved in the fossil record can be misleading because not every trilobite fragment equals a dead trilobite.

About 500 million years ago, trilobites such as this were common in the warm, shallow seas that once covered much of Indiana. Because violent storms commonly ripped up the shallow ocean floors, remains of animals as large as this were readily fragmented. A plethora of animals lived on these ocean floors, many of them scavengers. A hungry forager would eagerly pick apart a trilobite carcass that might have escaped violent storms.

This particular specimen must have been covered quickly by sediment, hidden for hundreds of millions of years from weathering and erosion.