Trilobites of Trenton Falls

The rocks in the Trenton gorge which are estimated to be approximately 450 million years old are rich in fossilized remains including an ancient armored jellyfish, echinoderms (ex. starfish), shelled mollusks with squid-like tentacles, snails and tiny moss animals. The one defining fossil of the region however, is the trilobite.

Trilobites are early arthropods that existed over 300 million years ago in the ancient seas. They were one of the signature creatures of the Paleozoic era which became extinct even before dinosaurs came to be. They are readily fossilized because of the high mineral content of their exoskeleton. No wonder they are the single most diverse group of extinct animals on record, comprised of over 10 orders, over 150 families, 5000+ genera and 20000+ species, the smallest measure under 3 mm long with the largest over 70 cm long. New species are being discovered every year.



John Sherman, the unitarian pastor and owner of the first residence and hotel on Trenton Falls, discovered one complete specimen of a rather large trilobite. He then brought the specimen to James Ellsworth Dekay, then a practicing taxonomist. DeKay thought this differed from the 5 previously described genera. In 1824, he described and named the new genus Isotelus, from the Greek isos (equal) and telos (end or extremity). Based on the large size of the specimen, he named the species Isotelus gigas. The photo is from the Yale Peabody Museum.