Chondrichthyan Finds in Iowa

[minnbuckeye]

This week, I took the time to break open the 6 chunks of matrix I had brought home from the Mississippian Burlington Limestone from a trip this Fall. My finds were not as good as other trips but it is always exciting to see what pops out of these rocks. My identifications are going to be educated guesses at best. I am not versed very well in Chondrichthyan recognition. The pictures 1,2 and 3 look like teeth but I can not find images that fit their looks. Could they be dermal appendages??

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[Jeffrey P]

That's a lot of shark for six chunks of matrix. Must be pretty rich stuff. Great specimens! Congratulations and thanks for sharing. 

[minnbuckeye]

18 hours ago, Jeffrey P said:

hat's a lot of shark for six chunks of matrix. Must be pretty rich stuff.

 @Jeffrey P, If you can find the thin layer that is called the fish beds, it is extremely productive at producing these teeth. Many more teeth of lesser quality were found but not shown. The seas back then must have been teaming with fish. But why in such a small layer?? Above and below it I can find just the occasional tooth. 

[deutscheben]

What a very nice variety of finds! I believe the first specimen is the base of some kind of cladodont tooth with some remnants of cusps preserved. 

[Elasmohunter]

Good finds, sir! Here are my thoughts:

Your large "unknown" with "maybe two fractured teeth" is curious to me. In my collections there, I haven't seen any teeth with a base that large. My immediate reaction was that the two smaller bumps were probably cusplets, not individual teeth.
 

The next tooth, labeled Mesodmodus, is not Mesodmodus, as it lacks the prominent protrusion in the middle of the tooth typical of this genus. Rather, this tooth looks to me like Orodus. Maybe O. mamillaris?

 

The next "unknown" could be a broken fragment from the side of another Orodus tooth. O. elongatus?

 

I cannot tell what "1.", "2.", and "3." as well as the other cladodonts are without seeing the side profile, but they're probably Stethancanthus, Cladodus, or "Cladodus" (i.e., a cladodont of some sort that needs revision). Sethacanthus will look like an "S" from the side, and Cladodus will look like a "C".

 

I'm not familiar enough with Saivodus to confidently ID it, but the one Saivodus tooth that I've seen resembled yours, so you may be right with those IDs.

 

I think you're correct with the Deltodus.

 

The next unknown is definitely a petalodont, but I'm not sure which genus of petalodont it belongs to; it could be Petalodus, Antilodus, or Tanaodus. Good job on that one!

 

The large Sandalodus tooth could also be a Deltodus tooth, but those genera need a lot of work, and many of their species are synonyms for one another, so Sandalodus is probably just as correct as Deltodus.

There isn't enough of the potential Deltodus/Helodus tooth to identify it, but it could be either of those, or also Leiodus.

 

I think some of your remaining unknowns are also petalodonts, and I think your remaining identifications of Orodus are also correct.

 

Once again, well done!

 

[minnbuckeye]

@Elasmohunter Thanks for the opinions on these finds. I should have checked here before reading my messages!! At least I had a few correct IDs.