Pectinid from the Pennsylvanian of Jacksboro

[BobWill]

I found this bivalve at the Lost Creek Spillway in Jacksboro Texas, Graham Formation. It's 30mm across and it came attached (post-mortem) to a nautiloid fragment.  It has been suggested that it could be Pseudomonotis sp. possibly based on it's inclusion on the fauna list but it sure looks more like either Dunbarella rectilaterarius or D. knighti neither of which are know from the site. Maybe it is some species of Pterinopecten from the Pennsylvanian if there are any. Any help would be great.