Mystery Ammonite

[Eocenecarnage]

I have no idea what genus, let alone species this ammonite is. I bought in the gift shop of a small geology museum about a year ago for $8.00. I have a few suspects including Didymoceras, Exiteloceras, or Prionocyclus. Anyway I am wondering if any of you can look at this ammonite from the photo and hopefully identify the species.

[Guguita2104]

It's difficult to see without better photos...However it seems a "piece" of an exiteloceras jenneyi....We will see the opinion of the experts.

Edited July 27, 2015 by Guguita2104

[Eocenecarnage]

Thanks for the help. I have better photos here.

[JohnJ]

It looks like a local find that was gifted to the museum shop to sell. What was the general location of the shop, and are similar ammonites found in that part of the state?

[jpc]

Of the three you mentioned, it is Prionocyclus. See that ridge running down the midline?... Prionocyclus. If it came from the Rocky Mtn area, I would say for sure Prionocylus, but if it came from somewhere else.... well, it is certaily NOT Didymoceras or Exiteloceras. Neither has that ridge nor the big ribs.

My guess is that it is local, and therefore, from the Frontier Fm or Carlile Shale, or whatever they call their equivalent in CO. Preservation suggests this as well.

[Eocenecarnage]

Thanks JPC. This did in fact probably come from Colorado. Thanks for your help