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BFunderburk

Mississippi Cretaceous Chalk Find- Jaw Or Crustacean Part?

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BFunderburk

Found OFTEN but without ID from any reference. Associated with shark's teeth, gyrodes, baculites, exogyra, agerostrea, mosasaur and enchodus teeth, etc.- in chalky Black Prairie bluffs, near Starkville/Oktibbeha County (northeast MS). About 1 1/2 inch X 1/4 inch. Help! (thanks!)

post-7693-0-17876400-1329554319_thumb.jpg

Edited by BFunderburk

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BFunderburk

Just to show a wider view of find site with more of "these" !

post-7693-0-12458200-1329556259_thumb.jpg

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FossilDAWG

I believe these are parts of the hinge of inoceramid clams (Inoceramus or Platyceramus). Some species were very large but had quite thin shells, which are sometimes not preserved or break up to tiny pieces as the chalk erodes. Only the hinge is thick enough to routinely survive. If you dig down to fresh Mooreville or Prarie Bluff Chalk you can find a variety of thin-shelled pectinids and inoceramids that you never find on the eroded surface. That's because the chalk swells quite a lot when it gets wet, which breaks up the very thin-shelled bivalves, and when the chalk dries out it becomes almost a powder that then blows away, scattering the fragments but leaving the heavier hinge in place.

Don

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vertman

I agree with FossilDAWG's hinge suggestion.

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BFunderburk

I am appreciative! And yet, because of the triangular, almost crocodile head and snout-at-end shape of these (not suggesting!), not so sure. Have looked at images of the species you identify, but haven't specifically seen this always triangular grooved part. I will DRAW the 3 views tonight and post. But, verily, you may be right on the money! Can you send a better photo of your fossil evidence for comparison? THANKS so much, Don, (and vertman)!

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BFunderburk

OK- more photos. Note the consistent triangular shape and undulations. Also- teeth-like joints on bottom side.

Are we convinced? Please help!

Best,

BFpost-7693-0-98333700-1330623930_thumb.jpgpost-7693-0-79833100-1330623951_thumb.jpg

Edited by BFunderburk

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Xiphactinus

Yup. Inoceremus hinges. I wish I had a dime for every one of those I've picked up thinking they were any number of vertebrate fossils.

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BFunderburk

Again, these are about 1" to 2" long/1/4" to 1'2" wide.post-7693-0-77686800-1330624449_thumb.jpgpost-7693-0-81237300-1330624466_thumb.jpg

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vertman

Yup. Inoceremus hinges. I wish I had a dime for every one of those I've picked up thinking they were any number of vertebrate fossils.

Find a hinge or two out there in the Niobrara, do you? I am just kidding. I know they are absolutely everywhere out there.

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BFunderburk

Clearly, I am being schooled here by the inoceramus/inoceramid hinge police. Thank you- and do you know that this Selma/Ripley/Demopolis Chalk prairie is most often compared to that of Niobrara? Love this, as I taught in Nebraska and was surprised to see many dear prairie flower friends here in MS! Also schooled in the dark, wondrous, paleo world of Loren Eiseley-

who still haunts me hourly- TO GO FORTH!

Still, a request- vertman, Xip, etc.- Please post photo of your inoceramus that most resembles mine- any guidebook/Google image results I can see are unconvincing!

Grateful!

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-AnThOnY-

They are crab, not clam. Undescribed species of crab/lobster. I am surprised you found so many close together though, very interesting. I usually find a few of them when I go out each time but not that many at once!

See http://www.thefossil...the-past-month/ also, site reference to Texas specimens towards bottom of page.

First person from Starkville I have seen on here! How long have you been in the area?

Edited by -AnThOnY-

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Auspex

They are crab, not clam. Undescribed species of crab/lobster...

Aren't they rather thick-walled for a crustacean shell?

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-AnThOnY-

They are believed to a type of burrowing crab that may be similar in type to recent ghost shrimp with large hard claws for digging and soft bodies that do not preserve. Again, its not described because a carapace has yet to be found, but a lot of research is going into finding evidence. Info from George Phillips (curator of the Mississippi Museum of Natural Science)

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ashcraft

My suggestion was going to be to contact George Phillips at the Mississippi Museum of Natural Science. I suspect he would solve the mystery quite quickly.

Brent Ashcraft

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Auspex

Thanks, Anthony; I did not really know what to think!

None of the pieces pictured show any hinge "teeth", but the thickness of the material seemed too great for much else...

Sounds like you have a handle on that, though. :)

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-AnThOnY-

Sounds like you have a handle on that, though. :)

One of the few things ;). I at least know the stuff from the area anyway. Other than that, its a toss up! Especially with all this Lee Creek material I have.

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BFunderburk

Wow! Now we're getting s somewhere. AnThOnY- you have the first other photo I've seen of this. I will write George Phillips at MMNS in Jackson, MS; just meet him a couple of weeks ago at Plymouth Bluff giving a talk about Pliestocene finds here. Meant to ask him about this species but- eye surgery got in the way. Will follow through.

I've taught at MSU since 1982! Usually fossilizing, hiking, canoeing every weekend.

Thanks so much, all!

Edited by BFunderburk

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Uncle Siphuncle

i have some of the same partial crab claws from the maastrichtian corsicana formation of texas...i guess they have preservational bias due to being the "bidness end" of the crab. george knows his upper k stuff quite well...

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Scylla

The fauna really reminds me of the Monmouth county, NJ fauna. Except our ghost shrimps usually have the whole claw preserved. Link

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Boneman007

I do not agree with the crustacean ID for the following reasons:

1. Lack of ornamentation. The large claws always have detailed ornamentation on the pincers.

2. Size. Crabs of this size are very rare and would not be associated as they are in the pic.

3. Inoceramas clams look EXACTLY like what is pictured. As stated earlier, the Niobrara is litterally covered in them. I believe these are very weathered.

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-AnThOnY-

I understand the first reason. But other than that I can't find any evidence of these being Inoceramas in nature, do you have an example of one intact on the clam itself?

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Uncle Siphuncle

I've not seen Inoceramus hinges personally, but those images would be insightful. A modern counterpart to what I'm seeing here as crab claw would be something like the Maine lobster claw. The claws tend to be smooth on the sides with the shell thin on the sides, with large, smooth bumps on the working surface of the movable and immovable fingers, similar to what is shown in Anthony's pics. It seems reasonable that the claw wall thickness would be highest where the claws see the highest forces, i.e. along the opposing pinching surfaces of the fingers, and that there could therefore be an associated preservational bias. None of what I've said is based on science, just observation, so it won't hurt my feelings if I'm clearly disproven, as I chalk that up as part of the learning process. There should also be some clear difference in material composition of Inoceramus vs. crustacean material on a microscopic level, regardless of preservational differences between formations....."Sho me da money!"

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Auspex

...There should also be some clear difference in material composition of Inoceramus vs. crustacean material on a microscopic level, regardless of preservational differences between formations...

post-423-0-87142600-1330712367_thumb.jpg

I have seen previous posts from Kansas where this structure was singled out as consistent with the thick, heavy areas of the Inocreamus shell.

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Uncle Siphuncle

To further this discussion, tonight I'll post pics of a full claw, one complete finger, and what I'm calling partial claws, all of a similar age to what Anthony has shown. The biggest complete claw I found was preserved only because it was tucked into the concave side of a Pycnodonte oyster, otherwise the thin walls and tall profile of the claw would have probably been relegated it to destruction when subjected to all the influences at play before, during and after preservation.

Out of the thousands of fossils I've found in the Corsicana formation, I've found many of these "partial claws", yet nothing like Inoceramus, a form pretty common through much of the slightly older Austin Chalk aged rocks throughout much of Texas. Instead at my site I see lots of oysters, and their hinges are different than the suspected "crab claws" through my eyes. However, presence of the Dakoticancer australis lagerstatte in this formation certainly denotes a crab friendly environment. Just sumpin' to ponder...

I enjoy these thought provoking discussions. I'm still learning about the formations I hunt, the forms found in them, and preservational biases therein. I think its most helpful to everyone following along when we try to back up opinions by citing diagnostic features backed up with photos and ideally, papers whenever possible. We all bring our observations to the table, collective scrutiny kicks in, and in the end we all walk away more informed. Good times!

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BFunderburk

OK, Boneman007, send comparable "exactly" pix. Please!

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