Bathyuriscus fimbriatus trilobite from the Marjum formation

Here is an uncommon trilobite from the Marjum formation of Utah, Bathyuriscus fimbriatus. This comes from the same area as the millions of Elrathia kingii fossils that are ubiquitous at fossil show, but from a slightly younger layer. You can tell this species apart from E. kingii by the larger pygidium and the thorax segments that extend just a little father than the margin of the pygidium. This specimen is missing the free checks, or librigena .

There is a good picture of a complete specimen of Bathyuriscus fimbriatus that can be seen on the Western Trilobite Association webpage.

The Marjum formation is middle Cambrian in age, Drumian stage (503 mya).