Nevada Carboniferous Shark teeth?

[andy_mnemonic]

Hello TFF!

 

I found these two pieces in Nevada while looking for some Carboniferous shark teeth and hope I found one.  They were located in the Bird Spring Formation north of Vegas which is Pennsylvanian in age.

 

#1

 

and #2 which could just as well be a brachiopod...

 

Thanks for looking!

[Petalodus12]

The first looks like a possible cladodont and the second looks like a brachiopod. I’d wait for a second and more experienced opinion though. Nice finds!

[Fossildude19]

@jdp

[connorp]

Some more pictures of #1 would help. #2 is a spiriferid brachiopod.

[jdp]

So that's Mississippian-Pennsylvanian boundary, and is more or less equivalent to the Surprise Canyon fauna:

 

https://www.cambridge.org/core/journals/journal-of-paleontology/article/carboniferous-chondrichthyan-assemblages-from-the-surprise-canyon-and-watahomigi-formations-latest-mississippianearly-pennsylvanian-of-the-western-grand-canyon-northern-arizona/6756DFC72DBDDA2ACB99D00D3D072DF6/core-reader?fbclid=IwAR0E1psGBZSGgC_DxRtzZOli5BpBNBvgML8blP5bFPd8ePO49lRhwdYywfc

 

I do think your suspicions are correct and the second fossil is brachiopod, but the first is definitely vertebrate. I can't say with certainty, because it is not fully prepared. A little bit of white vinegar might remove the surrounding matrix if it is limestone. If it's dolomite, that may not work.

 

From what I can see, it looks a little like the xenacanth Hokomata (see linked paper, figure 4:5-7) or like the denticles of cf. Hamiltonichthys (see linked paper, figure 9:28-29). But I have also seen chondrichthyan gill rakers that look like that. More prep would help.

[andy_mnemonic]

@jdp I gave it the vinegar treatment and this is what it looks like now.  I didn't think the vinegar would alter the fossil but it looks like it has taken a bit of it but exposed a bit more as well.