Olenina

Triarthrus is a genus of Upper Ordovician ptychopariid trilobite found in New York, Ohio, Kentucky, and Indiana, eastern and northern Canada, China 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. Pyrite preservation has given scientists a rare opportunity to examine the gills, walking legs, antennae, digestive systems, and eggs of trilobites, which are rarely preserved. Triarthr

Olenidae is a family of ptychopariid trilobites. Some genera, Balnibarbi and Cloacaspis, are thought to have evolved a symbiotic relationship with sulfur-eating bacteria from which they derived nutrition.

fossil genus of trilobites