Odd Boring Trace on a Conulariid jellyfish fossil (Missouri)

[Samurai]

Location: Missouri

Age: Pennsylvanian 

Stratigraphy: Iola formation 

 

 

Hello! Here is an odd find from the other day on this Paraconularia sp. fragment (lower half). I am not sure what organism left it but I was wondering if anyone on here recognized it as anything. I was thinking possible gastropod but I know other boring organisms existed back then.

 

 

 

 

There is a small odd indent near the base of the boring that perplexes me, making it hard for me to visualize where the organism would have been/moved while feasting.

 

 

 

[Rockwood]

Sorry, I see no indication of this being a conularid nor do I believe there is a boring on whatever it is.

[Advantage]

Isn't this just a weathered flint/chert?

[Samurai]

5 hours ago, Rockwood said:

Sorry, I see no indication of this being a conularid nor do I believe there is a boring on whatever it is.

 

2 hours ago, Advantage said:

Isn't this just a weathered flint/chert?

I apologize to the both of you, it appears I did not include enough images since I already know the species name and was wondering on the trace.

 

 

Lower Conulariid fragments appear all the time in this location, I thought they used to be inorganic myself until I started looking more into them.  The fragment with the boring trace (1) is the bottom fragment while another Conulariid fragment is seen above it (2).

 

For reference here is the lower half of a confirmed Conulariid that is complete, if you notice they both have that pyramidal cone shape leading to this base section.

(The one with a boring hole in question). I will admit this one is in pretty bad shape, but the square shape is preserved. (1)

 

 

(this is the other lower fragment with no borings) (2)

 

 

Also many Conulariids have a calcium phosphate test with "bumps" (fragment with drill hole) (1)

 

Compared to this one (bumpy texture on lower side)

 

 

Also when (1) is compared to a Conulariid upper half they appear more true conulariid like. Obviously they don't fit together since they are not the same specimen.  They are also the same phosphate blue, with odd white specs on them. 

Now for the drill/boring hole, it does appear off since my microscope camera has a bright rim of light on all sides so here is a picture taken farther away.

 

It looks to me, that something drilled into its surface inward. It looks like the animal went inside on a plane of weakness on Conulariids (their inward dipping corners as seen above), rather than the main body. It could have been a killing blow and made it easier to break off from the upper half when it got fossilized and dumped at this rockpile. 

 

here is an image of the main hole that appears to have penetrated the test (inner circle). It is deep and it's a bit hard to show,  but it is a "funnel" shape.

 

Now what I do not know about is this little "lip" attached to it. It does not go as deep as the main hole. I wonder if this is where it started.

 

This part seems to have a raised edge, I wonder if it was an immune response.

 

 

 

 

 

Edited 13 hours ago by Samurai

[Rockwood]

Now you're cookin'. The feature in question does look like something a gastropod might rasp out. 

[Jaybot]

I hunt in the same layers as Samurai here, and can confirm that is a conulariid; and that is how they look here.

 

I'm no expert, but gastropod boring was my first guess as well, since I have found gastropod predation on brachiopods just west of KC.