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Herb

Need Help With Id

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Herb

Hi all,

a friend of mine asked me to id a fossil he found, he didn't think my id was right so I said I'd post it for your perusal. It's from the U.Ordovician of Kentucky, Richmond formation, Louisville area. Any help will be appreciated. Thanks.

post-2520-0-76654000-1360544017_thumb.jpg

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Ramo

Looks like some sort of Placoderm plate to me. Sorry, but I can't offer much help other than that.

Ramo

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glacialerratic

Herb,

what did you ID it as? It does look kind of fishy. The Ordovician of CO. has jawless fish present (agnathans) -- Astraspis desiderata, but none of the plates found in the Harding Sandstone are present in the Cincinnati. The same for the early jawed fish, the gnathostomes. "A Sea Without Fishes" suggests the environment of the arch was not suitable.

That said, I seem to recall a post from around 2009 about finding a placoderm plate in the Louisville, KY. area. Is you friend sure of the age?

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squalicorax

Looks like a cheek of a trilobite to me

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Caleb

I'm thinking Trilobite fragment. Due to the size and pustulose exoskeleton, I'm going with the family Lichidae for the bug. Possibly the free-cheek, This is certainly a situation where in hand ID would be most useful.

Perhaps it's my imagination...

post-3840-0-76631800-1360593068_thumb.jpg

Comparison(Same family, different age, genus and/or species):

post-3840-0-06908300-1360593795_thumb.jpg

Edited by Caleb

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FossilDAWG

It looks trilobite to me too, though at the moment I can't point to a specific name. Placoderms with large plates might be expected in Devonian rocks, but in the Ordovician the fishy bits are small dermal denticles, not large plates; the actual skeleton was cartilagenous (as I recall anyway). A weaker argument is that fish are not known from the Ohio/Kentucky Ordovician (hence the title of the book "A Sea Without Fish"), though of course they could turn up there.

Don

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Indy

Trilobite seems logical

If it's trilobite ... "You know who" will probably drop by soon

and ID it to the species level ...Including what size shoes it wore !!

:P

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Vari Raptor

It's a placoderme for me...

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Herb

So far no fish in the Ordovician in the tri state area. (KY,IN,OH) . My thought was a partial cheek and spine of an Isotelus gigans? Still open to ideas.

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Ramo

My knowledge of that area, and/or time period is VERY limited, but I found this not too far south of Louisville a few years ago.

post-40-0-46464200-1360629079_thumb.jpg

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piranha

So far no fish in the Ordovician in the tri state area. (KY,IN,OH) . My thought was a partial cheek and spine of an Isotelus gigans? Still open to ideas.

Isotelus has smooth integument and the gross morphology doesn't look correct for a trilobite.

I'd say the spine attachment and adjoining margin suggest something other than a trilobite ID.

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Shamalama

My spidey sense is saying it's something in the Echinoderm family. God knows there were plenty of odd looking cystoids, et. al. around then.

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erose

Here is another SWAG: Eurypterid. I have a copy of the paper on Upper Ordovician Eurypterids of Ohio, 1964, by Caster & Kjellesvig-Waering. Although I cannot find an image or drawing that matches the exact shape the surface texture and general form suggest this possibility. There are several known species of the genus Megalograptus on Steve Holland's web site: http://strata.uga.edu/cincy/fauna/eurypterida/Megalograptus.html They are rare and only known from a few fossils in the upper Cincinnatian Richmond Group strata.

This specimen is strange enough to warrant a lot of study. Maybe a return to the site to search for more material.

One other possibility: It is an Isotelus fragment with an eroded shell.

2 cents...

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piranha

Here is another SWAG: Eurypterid. I have a copy of the paper on Upper Ordovician Eurypterids of Ohio, 1964, by Caster & Kjellesvig-Waering. Although I cannot find an image or drawing that matches the exact shape the surface texture and general form suggest this possibility. There are several known species of the genus Megalograptus on Steve Holland's web site: http://strata.uga.ed...ograptus.html They are rare and only known from a few fossils in the upper Cincinnatian Richmond Group strata.

This specimen is strange enough to warrant a lot of study. Maybe a return to the site to search for more material.

One other possibility: It is an Isotelus fragment with an eroded shell.

2 cents...

The cuticle of Isotelus is always smooth so I'm convinced we can rule out any trilobite. The pustulose surface on the mystery fossil is actually a very good match for Megalograptus. The attached photo shows the spines from the second walking leg on Megalograptus. Given the late Ordovician age and similarity in overall morphology it appears to be a portion of a Megalograptus second walking leg with spine attachment.

Congrats on the astute ID!

post-4301-0-61241300-1360701606_thumb.jpg

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squalicorax

Great find

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Herb

The cuticle of Isotelus is always smooth so I'm convinced we can rule out any trilobite. The pustulose surface on the mystery fossil is actually a very good match for Megalograptus. The attached photo shows the spines from the second walking leg on Megalograptus. Given the late Ordovician age and similarity in overall morphology it appears to be a portion of a Megalograptus second walking leg with spine attachment.

Congrats on the astute ID!

post-4301-0-61241300-1360701606_thumb.jpg

Excellent! That was my second guess, but I've never seen a specimen in this area. Thanks, great ID.

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Kentuckiana Mike

Nice ID and pictures!

I now remember a fragment of an Megalograptus ohioensis found in LaGrange, Kentucky in the same general area of where that one was found. The M. ohioensis fragment was donated to the Cincinnati Museum in 2009.

See pictures here: http://louisvillefossils.blogspot.com/2009/08/eurypterid-megalograptus-ohioensis.html

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Missourian

Megalograptus is ridiculously cool looking. If it turns out to be a piece of one, then the next question is: Is there more to be found? If it were me, I'd probably be out there turning over every single stone. I should know, because that what I did when I stumbled upon a partial eurypterid. :)

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erose

Upper Ordovician Eurypterids of Ohio, 1964, by Caster & Kjellesvig-Waering is the paper that described many of these. There are numerous plates showing lots of bits and pieces and a few articulated sections but no complete animals. That specimen from La Grange is one of the more complete appendages.

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GerryK

I'm in agreement with Caleb that it's the ventral surface of a lichid free cheek. He has given me many ventral lichid free cheeks to flip and prep, so I know what a ventral lichid free cheek looks like.

It's not a Placoderm because they didn't live in the Ordovician. It's not a Eurypterid because the fossil composition looks calcite and not chitin and the rock lithology looks wrong for Eurypterids.

Herb, if you could post a close up picture of the side of the rock so I could see the cross section of the fossil, it may help in indicating that it is trilobite.

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piranha

...I'm in agreement with Caleb that it's the ventral surface of a lichid free cheek. He has given me many ventral lichid free cheeks to flip and prep, so I know what a ventral lichid free cheek looks like...

Hi Gerry,

I have tried every way imaginable to make it fit as a lichid but I'm just not seeing it. Assuming it would have to be an Amphilichas, it still does not line up based on the spine. The slender spine on Herb's mystery fossil appears to be complete yet does not match the wide genal spine of Amphilichas. Of course a different lichid is worth investigating, so my next question is: which one?

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Missourian

Now that I think about it, I too doubt it being a eurypterid. Those tend to be impressions or carbon films at best, or at least what I've seen.

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MammothPaleoGuy

SEMI OFF-TOPIC

My knowledge of that area, and/or time period is VERY limited, but I found this not too far south of Louisville a few years ago.

Are we absolutely sure that you are in the Ordovician? I could SWEAR that this is a median dorsal or maybe a nuchal from some kinda placoderm . . . I'm leaning toward median dorsal . . .

diagram.gif

Plus the preservation on that thing that you found south of Louisville looks kinda like the Ohio shale fossils I've seen up around Cleveland.

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erose

I am also feeling less sure of the eurypterid ID. I'm also not convinced the surface texture is original. I have upper Richmond material that is very eroded. It appears etched to me. I'm also hedging my bets toward a trilobite of some sort.

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Herb

post-2520-0-89890300-1360958117_thumb.jpgpost-2520-0-11575300-1360958128_thumb.jpgpost-2520-0-31375200-1360958137_thumb.jpgpost-2520-0-92598600-1360958146_thumb.jpgpost-2520-0-56274100-1360958162_thumb.jpgpost-2520-0-96931100-1360958178_thumb.jpg

1) 100 % sure it is U.Ordovician, I collect in the area myself.

2) Isotelus sp. found in the near area.

3) Megalograptus found in same formation 20 miles away.

4) Ramo's fish fragment was found in the Devonian Black shale south of Louisville. I have found fragments there myself, roughly coincides with Cayahoga (sp.) black shale of Ohio.

5) Does not appear weathered in closeups.

Here are some new pixs showing close ups of spine and skin.

More fun for all! :D

post-2520-0-87111500-1360958164_thumb.jpg

Edited by Herb

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