Bathyuriscus

Bathyuriscus, genus of trilobites (extinct arthropods) that provide a useful index fossil for the Middle Cambrian epoch of North America (520 to 512 million years ago). In Bathyuriscus the head segment is well developed, and marginal spines are present. The tail region is large and has many well-developed segments. Several species of Bathyuriscus are recognized.