What on earth is this?

[Casper Voogt]

I have a regular collecting spot in Capon Bridge, WV, which is my go-to spot for Eldredgeops Rana trilobites. On my most recent outing I picked up this odd thing, and I have no idea what to make of it. There is a pencil just to the left of the fossil, for scale. The fossil is fairly flat, hardly three-dimensional, so no need for side photos.

 

It appears to be three-pronged and pyritized.. pyritized in the same way that the trilobites often are at this location. The local shale is early to middle Devonian, I *think* Needmore Formation.

Any thoughts welcome!

[Kane]

Possibly bryozoan.

[Casper Voogt]

thanks Kane! That does make sense.

[abyssunder]

There might be an interesting symmetry, or is just coincidental.

 

[jdp]

I think this might be a chunk of bone. Can you get a close-up photo of this?

[minnbuckeye]

Going out on a limb but if @abyssunder is correct on the symmetry and trilobites are common, how about a hypostome of some kind?? I don't know the size so it may rule hypostome out if large.

 

Mike

[Casper Voogt]

The hypostome hypothesis is an interesting one. I am too unfamiliar with trilobite morphology to judge that but the few images of trilobite hypostomes I've seen were in either one or two (even) sections, not three and not two uneven sections. The symmetry mentioned before I think was just coincidental. The middle rocky portion is just a raised bit of rock, nothing to do with the fossil. I attached an illustration.

 

Today I worked on this piece with my pneumatic jack to try and reveal the thickness of the fossil, and also to show what I suspected was a third section this pyritized portion of the specimen; I stopped before I got that far, because I was afraid of damaging the (supposed) third section if it was there. In so doing I did remove the iron-stained area shown in the earlier illustration of symmetry. 

 

These photos also illustrate that the fossil has little in the way of depth/thickness. It also has distinct striations all in the same direction, which does resemble what I have seen on hypostome illustrations.

 

I have been looking for some references on Eldredegeops Rana hypostomes and am not having any luck on that. I did read that their hypostomes are branched and on the large side (for manipulating prey), which some to believe supports the notion that these were predators.  What I have certainly looks branched and has the striations I have seen on other hypostomes, but I'd love to be able to compare this with actual photos or diagrams of other Eldredgeops hypostomes!

 

Edited August 12, 2018 by Casper Voogt

[piranha]

2 hours ago, Casper Voogt said:

...I'd love to be able to compare this with actual photos or diagrams of other Eldredgeops hypostomes!

 

 

This is not a hypostome.  Eldredgeops hypostomes attached for comparison.

 

figures from:

 

Miller, J. 1976

The sensory fields and life mode of Phacops rana (Green, 1832)(Trilobita).

Transactions of the Royal Society of Edinburgh, 69(16):337-367

 

[Casper Voogt]

Thank you Piranha! The mystery remains, but that's one thing ruled out!  It is also possible my mystery fossil is not from a trilobite, of course. 

[Reese the Rockhound]

I am a Charleston-based collector and am always looking for good hunting spots in West Virginia.  Could you post a map of Capon Bridge?

[jdp]

Increasingly convinced this is a piece of fish skull. I'd really like to pop this into a CT scanner.

[NickG]

On 7/30/2019 at 11:42 PM, Reese the Rockhound said:

I am a Charleston-based collector and am always looking for good hunting spots in West Virginia.  Could you post a map of Capon Bridge?

Capon Bridge is a one road town. Not much there. But the outcroppings in roadcuts all over are very fossiliferous.