Ray barb or fin spine or something else?

[rauhaus]

Hello! I found this chunk of something in Frankstown, MS while looking for shark teeth. There is so much petrified driftwood there and many pieces look similar to this. I picked this out at first thinking it was wood.. but I didn't see the little bumps along one side (I'm being very generic because I don't want to call it something it isn't and I'm not sure yet what it is ) until I got home. I also noticed when I got home that it is hollow and looks a bit like bone. After seeing this, I thought it was probably a fin spine or a ray barb. Others say it is a barb, but if it is, I'd love to know more. I would think it would have denticles along both sides, but the other side is rounded. Rays found at this location are Brachyrhizodus wichitaensis and Brachyrhizodus mcnultii.

Specimen is 2" long

[rauhaus]

I've done more research since I posted this and I think it is a chimera fin spine.

[JohnBrewer]

Looking good.

[non-remanié]

Yes, the fin spine belongs to a chimaeroid, likely Ischyodus sp.   I have found similar specimens in late Campanian of NJ.  

[rauhaus]

I have found some Ischyodus jaw sections here too. And this site is also Campanian. That must be it! Thanks, non!