Trilobite at Louisville Science Center - Elrathia kingii?

Here are a series of pictures taken of an imprint(?) of trilobite in the hands on activities in the Discovery Gallery of the Louisville Science Center. This trilobite does not look like anything I have found in the Louisville, Kentucky or southern Indiana area. Also I first thought the blackish rock was some sort of coal but after examining it seems pretty hard. The last picture shows the cut marks of probably a diamond circular saw blade.

Since it was an unknown trilobite to me I consulted the BEST trilobite fossil site on the internet Sam Gon III's http://www.trilobites.info/. It appears to me after looking at his drawings and images on the site, this speciment might be an Elrathia kingii. Specifically, the site lists it as Order: Ptychopariida, Suborder: Ptychopariina, Superfamily: Ptychoparioides, Family: Ptychopariidae. The site has a picture gallery with references to pictures on another site http://www.trilobite.com/ which sells Elrathia kingii trilobites that lived during the Middle Cambian in Utah. Also I believe it or another site noted that this trilobite is the most common one sold today that is intact.



Click on pictures to view larger version.



Part of the pygidium is missing. I count 12 thorax segments.

Bottom of plate that contains the trilobite. Rock is almost black to very dark gray in color.

Side of rock plate containing trilobite with maybe diamond blade cut marks. This specimen could have been part of a large group and was sold as an individual piece. If I had to guess, the trilobite size is about 3 cm long and 2 cm wide.