Green River fish - what do we have here?

[casadelshawn]

I got this fish with some others in a trade deal the other day; I was supposed to get a mixed box of Diplomystus and Knightia, but this guy stood out for me. Doesn't look like either, and seems a bit too big for Amphiplaga. Maybe juvenile Mioplosus? Anybody? Is there another photo that can help? Thanks for looking!

Edited May 12, 2020 by casadelshawn

[Fossildude19]

I think it's an Amphiplaga brachypterus. 

Mioplosus labricoides  would have two dorsal fins. 

 

Here is my Amphiplaga. 

 

 

And a comparison from Grande's 1984 Bulletin 63 "Paleontology of the Green River Formation, with a Review of the Fish Fauna". 

 

 

 

[casadelshawn]

Mystery solved. Thanks for your help!