Identification Request

[BLT]

While out fossil hunting in Alabama (Mississippian/Tuscumbia Limestone) earlier this week, I found a hash plate full of crinoid stem segments which also has a small fossil on it which I cannot identify. Is it a bryozoan? 

[Peat Burns]

My guess is shark tooth.  Let's see what others say.

[Mike from North Queensland]

It looks to have the texture of fish bone. 

I would try to dissolve some of the limestone away with some vinegar to expose some more of the fossil.

But remember to keep an eye on it to make sure it does not damage the fossil.

 

Mike 

[BLT]

20 hours ago, Peat Burns said:

My guess is shark tooth.  Let's see what others say.

 

14 hours ago, Mike from North Queensland said:

It looks to have the texture of fish bone. 

I would try to dissolve some of the limestone away with some vinegar to expose some more of the fossil.

But remember to keep an eye on it to make sure it does not damage the fossil.

 

Mike 

Thank you! After cleaning it with vinegar this morning, I took more pictures. Do the new pictures help at all with identification?

[deutscheben]

I definitely think it is a shark tooth- maybe Venustodus? 

[BLT]

17 minutes ago, deutscheben said:

I definitely think it is a shark tooth- maybe Venustodus? 

Thanks!  If so, then this is quite different from my usual finds. 

[Elasmohunter]

I would agree with the others that it's probably chondrichthyan. The fossil looks like it might be a cross-section of two teeth stacked on top of one another. Because I can't see anything other than the cross section, however, I'm hesitant to classify it any further. Venustodus definitely has an arched shape, though, so it could be that. I'd need to double-check to see if we've ever recovered an intact Venustodus jaw to see if their teeth occurred stacked like that, but I doubt we have. . . . Other strongly arched chondrichthyan teeth from this time include Helodus and Leiodus, and probably others.

Marine vertebrates alive during the Mississippian included bony fishes (Paleonisciformes), stem chondrichthyans ("acanthodii"), and chondrichthyans (Holocephalii and Elasmobranchii). I don't think your fossil is fish remains, because the only fish remains that I've seen from Mississippian Limestone have been their teeth and scales (which look nothing like this).

If you wish to keep dissolving the rock, you should be able to do so with straight, unbuffered, household vinegar. It's gentle enough to eat away the calcium carbonate matrix without destroying the teeth, but it will destroy any invertebrate fossils. Make sure to rinse the residue afterwards to prevent the formation of calcium acetate crystals. You may need a lot of vinegar and time, but at the end, you should have a nice paleozoic vertebrate fossil, which is definitely worth treasuring. Or you could, of course, prep it in-situ to preserve the position in which they were buried, and given their cool juxtaposition, I would actually do that instead of complete acid dissolution.

Nice find!

Edit: One other possibility would be a section of a tooth whorl. If that's the case, then that would be super cool, and I definitely would try to prep it in-situ to preserve their juxtaposition.

Edited July 28, 2019 by Elasmohunter

[BLT]

@Elasmohunter Thank you so much for all of the information!

[Elasmohunter]

@BLT Glad to help! Let me know if I can be of any further service.

[jdp]

Definitely vertebrate. Could potentially be a piece of ray-finned fish too. I don't see any particular reason to think it's a shark tooth. Could be a fin spine from an acanthodian or maybe a piece of cranial bone from a ray-finned fish.

[deutscheben]

My guess of Venustodus was based on the general shape, but this image from Elliott, David K., et al. “Chondrichthyans from the Pennsylvanian (Desmoinesian) Naco Formation of Central Arizona.” Journal of Vertebrate Paleontology, vol. 24, no. 2, 2004, pp. 268–280. JSTOR, www.jstor.org/stable/4524715 shows a particular similarity, including the very arched shape and the depression or channel on the lingual side. 

 

[BLT]

Thank you @jdp!

 

42 minutes ago, deutscheben said:

My guess of Venustodus was based on the general shape, but this image from Elliott, David K., et al. “Chondrichthyans from the Pennsylvanian (Desmoinesian) Naco Formation of Central Arizona.” Journal of Vertebrate Paleontology, vol. 24, no. 2, 2004, pp. 268–280. JSTOR, www.jstor.org/stable/4524715 shows a particular similarity, including the very arched shape and the depression or channel on the lingual side. 

 

@deutscheben I have been googling all of the suggested identities. Your image I. appears to be an exact match with what I’m seeing in my rock. Thank you!!

[Mark Kmiecik]

I believe it's the alien symbol for "parallel parking only". 

[BLT]

34 minutes ago, Mark Kmiecik said:

I believe it's the alien symbol for "parallel parking only". 

Parallel parking only translates to keep on driving for me.