Unknown Pennsylvanian Period Fossil

[Roz]

I found this at the recent Jacksboro Trip in Texas. It is Finis Shale and

is from the Pennsylvanian Period. I know there are a lot of members

that hunt this period and also the Jacksboro site. I posted these pics

on the thread regarding the trip but thought it might be better to get an

ID on this section of the forum. I am hoping someone has an idea.

Found in association with echinoid plates and spines.

The first image is for scale.

[Auspex]

I wonder whether it might be regurgitant (or coprolite) from a shell-crusher shark/ray?

[fossilized6s]

I wonder whether it might be regurgitant (or coprolite) from a shell-crusher shark/ray?

Very great hypothesis! It looks like a jumbled mess to me. Coprolite seems very plausible.

[Fossildude19]

Neat mystery, Roz!

The two jagged edged items look kind of arthropodish to me.

Just a wild guess on my part, though.

Hope someone can id this for you.

The echie plates and spine are neat too.

Regards,

[Roz]

I can't be 100% certain but I don't think it's coprolite.

I thought it has a arthopodish look to me too, Tim..

[fossilized6s]

It looks like a broke sea urchin with two arthopods inside. Very strange piece! What's the black smeer? Looks like sharpie.

[fossilized6s]

Roz, can you take a close up of the lower large inclusion and the underside?

[Tethys]

I also see sand cast of the inside of an urchin who ate a crab, but that squarish wood piece at the bottom of the 1st photo makes me think it could be something like a mantis shrimp burrow.

[Auspex]

There's a lot of interesting things associated here:

#s 1; echinoid plate fragments

#s 2; 'crablike' fragments

# 3; Is this a tooth?

How did these things come together?

[fossilized6s]

It does look like a fish tooth. I think this is the "new" big mystery. It's pretty cool no matter what.

[trilobiteruss]

#3 almost looks like an echinoid spine rather than tooth but not enough exposed for sure. With other echinoid parts that may be a possibility though?

[Xiphactinus]

could the "crab parts" be the "Aristotle's lantern" structure on the inside of the echinoid?

[JohnJ]

could the "crab parts" be the "Aristotle's lantern" structure on the inside of the echinoid?

...that would be my first guess, too. I would try to rule out the obvious associations, first.

Tooth description - Here. Awesome find, Roz.

[Roz]

It looks like a broke sea urchin with two arthopods inside. Very strange piece! What's the black smeer? Looks like sharpie.

It is.. The stuff is so tiny I frequently mark spots I am interested in so I don't have to look at the whole thing.

Saves me time..

[Roz]

could the "crab parts" be the "Aristotle's lantern" structure on the inside of the echinoid?

I hadn't thought of that!

[Roz]

...that would be my first guess, too. I would try to rule out the obvious associations, first.

Tooth description - Here. Awesome find, Roz.

Thanks, John!

[Roz]

I think you all are onto something with the Aristotle's lantern. I have been comparing images..

[Coco]

I am not sure it is an Aristotle's lantern. Here is the one of a recent sea urchins to compare :

Coco

[Roz]

Thanks, Coco, I was hoping you would chime in..

[Roz]

There's a lot of interesting things associated here:

~.JPG

#s 1; echinoid plate fragments

#s 2; 'crablike' fragments

# 3; Is this a tooth?

How did these things come together?

The third one is an echinoid spine. A secondary one I think.

[Roz]

I see a 4th one although it differs in appearance (no claw features). It has an X on it and part of it's back

is exposed which I also placed an X on. I hope this may help further. Also a pic of the back

but I just see a few spines..

[Auspex]

There is a lot of mashed-up urchin there, but something else is going on too.

[Roz]

I agree!

[fossilized6s]

That large piece in the front looks like a modern day razor clam.

I think we're just identifying the individual species and not the fossil as a whole. I still think Auspex's theory of coprolite or ancient regurgitation is the closest explanation to why all of these different objects have come together.

[BobWill]

Hash ball

That thing is making me dizzy!

Just in case you need one more possibility for #3, the top part looks like some scaphopods I've found there.