Looking for help with Trilobite ID

[fossilcrazy]

I find myself unable to attach a species/genus name to the pair of trilobite pygidia I found in the Ibex area of Utah. The closest I can get is Ectenaspis judging from the form. The plate of two pygidia  were found in the float of the Wah-Wah and Fillmore formations. They are weathered with some shell material, but not enough to see terracing or effacement. Found near the top of the ridge, they have to be Ordovican, but I can't be positive which formation it was situated. This genus is well know from the Maquoketa of Iowa and Decorah of Wisconsin, but I find no examples from elsewhere. A little help if someone has info. Thanks.

[piranha]

It could be a new genus or a friend suggested the possibility it is the mature holaspid form of: Trigonocercella acuta

The scale is approximately 1.5 cm length on the pygidia from Hintze 1952 (only figured specimens in the literature).

 

 

Hintze, L.F. 1952

Lower Ordovician Trilobites from Western Utah and Eastern Nevada.

Utah Geological and Mineralogical Survey, Bulletin, 48:1-249

[fossilcrazy]

Thanks Piranha,

Looks good for a possibility. I was hunting with two very knowledgeable Utah Trilobite hunters, They didn't know what we were looking at either. The area was filled with parts of very large Isotelus (and I do mean BIG). Only this plate had these kind of parts. Normally, I would discard a couple Pygidia, but not when I cannot identify my find.