Strange fossil: any idea what it could be?

[xanthous]

Here's a YouTube video of it.

Anybody have any clues?

[DrFidelius]

First guess- a trilobite molt. That is, the preserved shed exoskeleton of a trilobite.

[xanthous]

Originally Posted by DrFidelius

First guess- a trilobite molt. That is, the preserved shed exoskeleton of a trilobite.

Super cool- I'll do some research.

[Blake]

I would guess it's an endocast of an crayfish curled into a defensive ball. Basically what you are seeing is what the thing looked like without its shell.

A couple of decent photos would be more useful than a low res video with the thing covered in shadows where the holder never stops moving the bloody thing.

[xanthous]

I'll post some photos. I figured not being able to see it turning in 3-D would make it harder to ID. My bad.

[Cromwell99]

I reckon that's a relative of that S. Palin woman.

[Blake]

Hey, Cromwell99, I know you're knew here. so we should clue you in: political jibes are verboten in GQ. They cause too many arguments.

[samclem]

Originally Posted by Cromwell99

I reckon that's a relative of that S. Palin woman.

Originally Posted by Blake

Hey, Cromwell99, I know you're knew here. so we should clue you in: political jibes are verboten in GQ. They cause too many arguments.

As Blake said, General Questions is the one forum where politcal potshots just tend to derail a thread. No warning, go and sin no more.

samclem, Moderator

[xanthous]

Here's a link to an album of still shots I took of it.

[Blake]

Originally Posted by xanthous

Here's a link to an album of still shots I took of it.

This is a Private Album

Please enter the password from album annewaldron to view this private album.

[Polycarp]

Originally Posted by xanthous

Here's a link to an album of still shots I took of it.

Well, yeah. But for the rest of us, it's a link to a private album requiring a password we were not given to access it.

[xanthous]

Son of a b!tch. The universe is not on my side in this. Back in a bit with a different attempt.

[DrFidelius]

Okay. That makes it likely to be an artifact or remnant of an Elder Thing, and so the Great Old Ones are altering probability to keep it from being recognized and invoked.

[xanthous]

Here you go:

Fossil
Fossil
Fossil
Fossil
Fossil
Fossil

[Mangetout]

The first image resembles the underside of a crab - there seems to be a sort of tucked-under tail.

The third image resembles the top carapace of a crab.

The weird split structure may actually be an imprint of a burrow or depression that (if it's a crab) it excavated to accommodate its legs (if that's the case, the legs may still be very well preserved inside those paired structures, but I don't recommend damaging it to find out)

[mutantmoose]

That is a weird one. Why don't you post the picture on a fossil identification site like fossilweb.com so that a load of fossil geeks can have a look at it?

I clicked on a few pictures on their specimen list but none of them seemed to fit apart from the Coilopoceras which is at least spherical.

If that doesn't work you could try showing it to a natural history museum (or emailing the pictures to them if you don't live near one).

I'd be interested to know what it is.

[xanthous]

Originally Posted by mutantmoose

That is a weird one. Why don't you post the picture on a fossil identification site like fossilweb.com so that a load of fossil geeks can have a look at it?

Just posted to FossilWeb- thanks! I also have a friend going to an upcoming Fossil/Rock/Mineral show and he might take it with him.

[jjimm]

There wasn't an ancient crashed spaceship near where you found it was there?

[xanthous]

Originally Posted by jjimm

There wasn't an ancient crashed spaceship near where you found it was there?

There was just a tornado there! (Dexter, Michigan)

[jjimm]

Internal structure.

[xanthous]

Originally Posted by jjimm

Internal structure.

Solved! I'm gonna try to get some DNA pulled from this bad boy and grow me one in a petri dish. If I don't check back in here, you might want to call these guys.

[F.Pu-du-he-pa-as]

Can you tell us the location where it was found? That would give us the opportunity to look up the age of the rocks it could have come from, and narrow down the options.

[CC]

My guess: the head of a crinoid - a sea lily.

[xanthous]

It was found in Dexter, Michigan.

[xanthous]

This is my favorite feature of this thing.

It appears to be the end/bottom part of the segmented shape

[CC]

The segmented view is one reason I thought it might be a crinoid head. The calyx, or whatever they call that part of the animal that connects the body with the stem looks something like that, in large crinoids I've seen. I imagine the geology of Dexter is not too far from the geology of the far south suburbs of Chicago, where there's an enormous open-faced limestone quarry with, I believe, animals about that size. The age of the rocks may be similar.

[Mangetout]

I did wonder if it could be a crinoid, but couldn't find any very similar examples. Another possibility is some kind of brachiopod - these often look like bivalve molluscs (but are not closely related)

[xanthous]

Originally Posted by Mangetout

I did wonder if it could be a crinoid, but couldn't find any very similar examples. Another possibility is some kind of brachiopod - these often look like bivalve molluscs (but are not closely related)

There is something bi-valve looking about this thing (The second pic in that original group I posted was a side view that is kind of clam-shaped)

[CC]

Thought that, too, and I've seen brachiopods about that size in that same formation, too.

[F.Pu-du-he-pa-as]

Originally Posted by CC

My guess: the head of a crinoid - a sea lily.

Close. I think it's part of the calyx (head) of a blastoid.

The thing about crinoid calyces is that, as far as I know, they were made up of rows of nondescript calcite plates which frequently disassociated upon death. The arms attached at the top, and collected food and passed it down to the mouth, which was located at the top of the calyx. There is a brief discussion of crinoid morphology here.

Blastoids, on the other hand, were built on much the same idea-- a head on a stalk, with arms attached to the head, but the implementation was somewhat different. The head was built of far fewer plates which were solidly attached to each other. There were five ambulacra that ran down the length of the blastoid's calyx, one on each side. They were basically feeding grooves, what the blastoid's tube feet came out of. The grooves and lines of holes that you can see on your fossil bear a strong resemblance to these ambulacra, as you can see here.

I think your fossil is embedded in a larger rock which has also been highly eroded-- look how spherical the rock is, and how little relief there is on the fossil itself. Judging from the way the ambulacra taper, I'd guess that in this picture, you're looking at the top of the calyx.

[CC]

Bingo! Blastoids, all right.

[GreasyJack]

It looks to me like it's way too big to be a blastoid. They're usually only about an inch across and I believe the biggest they come is about 3 inches.

I think it probably is a crinoid, either a well-preserved calyx or maybe a holdfast. I think the part that looks bivalvey is a red herring. The roundness may just be from the mineralized nodule in which the fossil was preserved and the odd texturing and big crack are just from weathering.

[F.Pu-du-he-pa-as]

Are you sure? If you watch the video, it looks like the fossil is about as long as two joints of the OP's fingers, which on me, at least, would be 2-2.5 in. This paper has a blastoid size chart for one particular species of blastoid, and the largest ones seemed to be about 4.5 cm by 3 or 3.5 cm, which would still be about right.

[xanthous]

I found out that this was found next to a pond in Perrysburg, OH, which is a bit south of where I originally thought it was found.

I've been looking at pics of crinoids, and it IS possible that it has some feeding-arm like lines coming out from the top of the calyx part, if that is indeed what it is.

It's just weird that the shape of the rock around it, including the split, is all so symmetrical.