Unknown fossil

[sTamprockcoin]

This came from a Bloomsburg/Mifflintown formation - Silurian exposure. It was in piece of waste as I was trying, unsuccessfully to get a cephalapod out. I see parallel sets of circles on either side of a ridge. The fossil is about 1.5 centimeters long. Any ideas as to what this might be?

Edited July 21, 2017 by sTamprockcoin
forgot a word

[DrDave]

it's small, but could it be a placoderm? 

[izak_]

Fish are incredibly rare in the silurian rocks. But if it was, what part of the skull would this be from? 

[DrDave]

 

I'm probably over interpreting from too few images, but I'm seeing a triangular wedge shaped structure. 

 

Or could it be a braincase type of fossil, also incredibly rare. just going with what my eyes are seeing...

from: http://palaeos.com/vertebrates/acanthodii/acanthodii.html

[izak_]

Well first of all, are fish even known from the area it was found in? 

[sTamprockcoin]

I've been collecting this site on and off for years now and this is the only thing like it that I've ever seen.

[DrDave]

Would love to see any Admins/experts chime in on this. Could you post a couple more images from different angles?

[sTamprockcoin]

Its an area that has been overlooked for the most part. The site itself is in a fairly recent (less than 20 years) road cut. I'm not good with field identification of geology and I can't find anyone local who can be bothered to SHOW me how to id the devonian / surilian layers which would go a long way in helping my interpertation.

What angle would be helpfull/ It is small and "thin". I hesitate to do any further prepring since it also seems soft.

[sTamprockcoin]

I've never seen or heard of fish but lots of spiral shell casts, straight nautaloids (cephalpods), brachipods, corals, that kind of life.

[trisk]

The ridges seem almost too regularly spaced in the first photo, like a spiny nautiloid. Additional shots of the most exposed apex and where it seems to extend laterally into the matrix would certainly help, since the appearance of a wedge could just be a trick of the light. There also seem to be tiny bumps and pits on parts of the surface if I'm not mistaken.

 

This is a really fascinating fossil!

[EMP]

19 minutes ago, Foozil said:

Well first of all, are fish even known from the area it was found in? 

 

Yes. Placoderm have been recorded in relative abundance from the Wills Creek (the formation directly on top of the Bloomsburg and McKenzie (Mifflintown) Formations. The Bloomsburg in Pennsylvania has also revealed locally abundant fish remains.

[Miocene_Mason]

Rare or not, I see a placoderm fish.

[Cluros]

It looks like a placoderm or at least part of a fish skull.

[izak_]

If it is (which it probably is), congratulations on such a rare find.

[sTamprockcoin]

Wills Creek clicks as there are outcrops of that within spitting distance. Like I said I'm much better at reading books than rock layers!

[Miocene_Mason]

3 minutes ago, sTamprockcoin said:

I'm much better at reading books than rock layers!

I would argue they are in many ways the same, both are read in a definite way, that changes regionally. Both contain information which is recorded for a significant period of time, and both are a heck of a lot of fun to open up and see what's inside!

[sTamprockcoin]

Sorry for the bad photos earlier. Maybe these will help.

[izak_]

Watch out, some of its flaking. might need some paraloid or something

But if its placoderm or any other armoured fish, the bone shouldn't flake. Could it just be a mineral coating around it?

[DrDave]

With new pics, I'm thinking it could be the braincase of a placoderm. 

[sTamprockcoin]

Thanks for all the help.