Very Curious Specimen from the Wilson Clay Pit

[dre464]

On our last excursion to the Wilson Clay Pit, I stumbled across this curious specimen.  It was mostly covered in matrix and I spent some time cleaning it up.  The piece has a curious shape.  It has a "V" shape, with one side curved and covered with striations.  The other side of the "V" is straight and flat.  The two sides of the "V" are connected with a flat plane of material, reminiscent of a scapula.

The complete specimen is below.  The scale is in centimeters...

Below is a close-up of the striated, curved part...

The other side of the "V" has a rectangular cross section (at least the part that is exposed--see lines)...

The exposed ends of the curved piece are shown below...

I know that the Wilson Clay Pit is well known for various Paleozoic sharks.  Do these "bones" appear to be shark-like, or are they, perhaps, some type of large boney fish?  We've had some luck with discovering shark cartilage at the site in the past.  But this seems to have a different texture.

I'm also going to send Dr. Maisey some photos to see if he can help identify it.  In my last correspondence with him he welcomed the chance to view any other specimens I might come across.

Any help that the great folks on TFF might give will be greatly appreciated!!

[BobWill]

I agree, it doesn't look like cartilage, at least not what I've seen. Maybe it's cartilage I haven't seen

I don't know my vertebrates well enough to identify them well, but I suppose it could be something else too. Dr. Maisey can at least rule out shark if it's not that.

The layering suggests shell material.

[ynot]

I agree with shell fragment.

 

Tony

[Mike from North Queensland]

+ 1 for shell material from photos.

But I am not familiar with preservation from the location.

Mike D'Arcy

 

[dre464]

I had thought that it might be shell at first as well, but I was unaware of any bivalves that were this big!  At least, until now.  You guys got me searching for large Pennsylvanian bivalves in Texas, and this is one that I turned up on pennsylvanianatlas.org.  Behold, Myalina subquadrata [or Myalina (Orthomyalina) subquadrata - I've seen it both ways...]. 

 It is known from the Virgilian of Texas, which is the correct time period, and it is mentioned from the Harpersville Formation in the University of Texas Bulletin No. 2132 - Stratigraphy of the Pennsylvanian Formations of North-Central Texas, which is the correct formation for the Wilson Clay Pit.

The shape is very similar, with one side curved and the other more straight.  The size is similar as well.

Is this a possibility?  If so, I probably won't bother Dr. Maisey...

[doushantuo]

Large pteriomorphs are not THAT unusual,so yeah ,it think it's a possibility