Two Pyritized Triarthrus Trilobites With Appendages - New York

The localities that preserve trilobites with soft-bodied preservation can probably be counted on one hand. One of these localities is where this specimen is from, the historic Beecher's trilobite beds in the Lorraine Group of New York. Less than a decade ago a new locality was discovered a short distance away that has produced amazing, soft-bodied preservation of trilobites and other organisms. Because of the rapid burial of the trilobites, in an anoxic environment, the soft body parts were replaced by pyrite, preserving details not typically seen.

Trilobites were a very diverse group of extinct marine arthropods. They first appeared in the fossil record in the Early Cambrian (521 million years ago) and went extinct during the Permian mass extinction (250 million years ago). They were one of the most successful of the early animals on our planet: over 25,000 species have been described, filling nearly every evolutionary niche. Due in large part to their hard exoskeletons (shells), they left an excellent fossil record.