Unknown fossil Utah, Cambrian?

[ptera]

Not sure what this could be. I am pretty sure this is cambrian maxfield formation. Any guesses? (It might be possible that it is one of the other carboniferous limestones that lay above, but those usually look different and have different fossils)

 

[Rockwood]

Maybe a drop of acid to test the limestone alternative ?

[piranha]

Looks similar to Yuknessia which has been reported from the Marjum, Spence and Wheeler formations.

 

 

LoDuca, S.T., Caron, J.B., Schiffbauer, J.D., Xiao, S., Kramer, A. 2015

A Reexamination of Yuknessia from the Cambrian of British Columbia and Utah.

Journal of Paleontology, 89(1):82-95  PDF LINK