Triarthrus
 Triarthrus is an Upper Ordovician trilobite found in New York Ohio Kentucky and Indiana eastern and northern Canada and Scandinavia. It is the last of the Olenid trilobites a group which flourished in the Cambrian period. The specimens of T. eatoni that are found in the Beecher's Trilobite Bed Rome New York area are exquisitely preserved showing soft body parts in iron pyrite.