Help with large Carboniferous fish tooth

[fossilized6s]

Hey guys. I'm looking for some help with this large mystery fish tooth from the late Carboniferous of Illinois. 

 

The closest match i can find is from the Devonian lobed finned fish Hyneria. But this is late Carboniferous almost Permian. Another contender just based on size is the Rhizodont. But it's not rounded. This tooth flattens out to two cutting edges that are very sharp. It honestly reminds me of a Barracuda tooth. 

 

This broken tooth measures about 20mm, but would have most likey been around 30mm if complete. It is associated with a Megalichthys scale and Orthanthus teeth. 

 

Any thoughts? 

 

 

 

 

 

 

[Fossildude19]

@Archie  @jdp

[Miocene_Mason]

Nice tooth! Definitely some lobefinned fish. Hope someone can ID it for you properly.

[hemipristis]

very nice!   The only thing I know of to compare to is the Hyneria lindae teeth from Red Hill, PA (Devonian). They possess lineations up the length of the teeth while yours cease half-way up, so it's likely not that.

[jdp]

I've regularly seen similar teeth attributed to Ectosteorhachis. Not saying that's definitely what this is, but I'd have a hard time giving you a better ID without histological sections.

[fossilized6s]

Thanks everyone.

 

A friend had a chance to show this to an expert, and i was told to label it as 'undetermined Sarcopterygii'. He believes it probably belongs to a large Megalichthys type fish, but isn't sure. 

[Archie]

Nice tooth and association! Most of the Rhizodont teeth I find in the Carboniferous of Scotland are round but some are flattened with a sharp edge like this too.