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KimTexan

Modern or fossil clam?

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KimTexan

I went out to the North Sulfur River (NSR) yesterday and went down a particular feeder creek. Along the creek I kept finding clam shells that looked modern, but not like any fresh water clam that I’ve ever seen before. 

I have never seen this category of preservation of clams in the NSR or elsewhere in Texas for that matter. 

The formation out there is Ozan of the Cretaceous. If they are Cretaceous they are quite remarkably well preserved.

There are 2 varieties of clams as best I can tell. There is the smaller one that is smooth and then the larger that have a wavy or ruffled shell. Both have fairly heavy, thick shells that are a beautiful soft pink/baige pearly color.

Here are the smaller smooth ones.

633B7DF6-1838-4881-A721-2513FF40890A.thumb.jpeg.f37c0890ec632b2063c9d9340c3d5f68.jpegB454DCDF-3F45-4FB3-98C4-39681C381EE6.thumb.jpeg.971b5977805453d7b376f4f269004fb8.jpeg

One up close.

B662CF88-2E90-4201-BA4B-D1AADED6BC42.thumb.jpeg.70b4d4625c67f77c44b2d58047ad6dec.jpeg

Here are the ones with wavy shells.

556B13FE-FEB1-4017-9AEA-7FB751D8B4C0.thumb.jpeg.66a2153bbb5c2c036e1c2b83623e6d5b.jpeg86A342ED-AE96-4AA2-BCB6-0818B24D3DC2.thumb.jpeg.2896bb3e93806f482e13e2a609d05ff4.jpeg

 

I also found 2 modern fresh water clam shells that are common in Texas

. Their shells are pretty thin and light.

3401C80A-4ACD-4AAC-9E7D-C68333B9AC40.thumb.jpeg.c686047ad7bb77f5b1ab51a383a58bad.jpeg

E04BFB7E-4D88-4D3D-B54A-0FB0EAA8813D.thumb.jpeg.75154f9ee5eeaca399e12de309b159ef.jpeg

 

Anyway, can anyone tell me if the first 2 kinds are even fresh water? If so I have never seen a fresh water clam like them. 

I think they are Cretaceous, but I have never seen such preservation in Texas.

Any thoughts or comments would be appreciated.

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Rockwood

Just a hunch: Cretaceous fossil.

The smooth one that is.

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-AnThOnY-

They all look modern to me.

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KimTexan
18 minutes ago, -AnThOnY- said:

They all look modern to me.

Do you know of any Texas fresh water clams that look like that? I’ve spent my whole life living in the South hiking in creeks anywhere from Virginia, Florida, Mississippi, Tennessee, Alabama, Texas and Arkansas and I have never seen a fresh water clam like that. I’ve hike spots across North America for that matter, with the exception of New England and north of there and never seen a fresh water clam like the wavy one.

The preservation looks modern, but the two modern clams aren’t chipped and they’re thin and fragile. The thick, heavy ones are all chipped, which makes me think they have been around a long time.

I just saw Dan’s, @Uncle Siphuncle post about the mammoth tusk. I now tend to think that they could be Pleistocene that washed into the creek. That would make more sense than Cretaceous.

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thair

Kim

The wavy one is modern if that's the one you are asking about. I have found living ones like those in Lake Brownwood. One thing to note however is these can also be found in Indian campsites quite a distance form a water source.

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Uncle Siphuncle

I’d wager modern.

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-AnThOnY-
31 minutes ago, KimTexan said:

Do you know of any Texas fresh water clams that look like that? I’ve spent my whole life living in the South hiking in creeks anywhere from Virginia, Florida, Mississippi, Tennessee, Alabama, Texas and Arkansas and I have never seen a fresh water clam like that. I’ve hike spots across North America for that matter, with the exception of New England and north of there and never seen a fresh water clam like the wavy one.

The preservation looks modern, but the two modern clams aren’t chipped and they’re thin and fragile. The thick, heavy ones are all chipped, which makes me think they have been around a long time.

I just saw Dan’s, @Uncle Siphuncle post about the mammoth tusk. I now tend to think that they could be Pleistocene that washed into the creek. That would make more sense than Cretaceous.

 

I've seen them in the Trinity with pronounced ribs on them like that.

 

I will agree, however, that it is certainly possible that they could be Indian campsite related.

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Herb

They look modern to me also, though you can get Cretaceous shells that are preserved like that

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KimTexan

Let’s not take the preservation into account. If we can identify the species then we will have the answer. The last time I had this dilemma it was Cameleolopha bellaplicata  oysters in Post Oak Creek which a number of people told me they were modern. I thought they were Pleistocene, but turned out to be Turonian, upper Cretaceous in age. The preservation seemed too good for that, but you can’t argue with a defined species and established period it shows up in.

Who are some good bivalve people on here? Maybe @Ludwigia, @fifbrindacier Or @DPS Ammonite have some thoughts. @abyssunder can almost always come up with a reference.

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Peat Burns

They both look like Unionidae. The first one reminds me of Amblema plicata.  Without looking it up, I don't know if they are found in your area of Texas, but this would be one to compare to and check range / distribution. 

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abyssunder

Maybe they are Unionidae bivalves.

 

Peat beat me to it.

Edited by abyssunder

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Peat Burns

The second one might be Pyganodon grandis.   Again, this is off the top of my head, and just a suggestion for you to follow up on

 

Also, you may wish to check with Texas state law. I know that in Michigan it is illegal to take any unionid shells, even if dead ,without a permit.  It is unfortunate, but there are unscrupulous people who take them live, and there is no way to tell that a dead shell that has been cleaned was not taken alive. Many of the unionid mussels are in extreme Danger.

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JohnJ

Not sure of the species @KimTexan but I have seen both types, with their live creators, many times in Texas rivers and creeks.

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Fruitbat

The ones with the 'wavy' shells definitely remind me of Amblema plicata (kudos to @Peat Burns) , the 'Threeridge' mussel (one of the Unionidae), which is currently extant in the North Sulphur River (though not common).  I have found fairly large concentrations of these in some of the Late Pleistocene/Early Holocene sediments near the Hwy.24 bridge.  The smaller, smoother ones may be Lampsilis radiata, another member of the Unionidae which is also locally common in Late Pleistocene/Holocene sediments on the NSR.  Shells of this mussel are also relatively abundant in certain areas.  

 

Back in the 1980s, a friend of mine and I found a largely-complete skeleton of Bison antiquus resting on a layer of both of these mussels in the bank of the NSR close to the Hwy.24 bridge.  The late Chuck Finsley of the Dallas Museum of Natural History (now the Perot Museum) submitted them to one of his experts who identified them.  Apparently they were among the favorite mussels used for food by the Native Americans who used to inhabit the area.

 

-Joe

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KimTexan
1 hour ago, Fruitbat said:

The ones with the 'wavy' shells definitely remind me of Amblema plicata (kudos to @Peat Burns) , the 'Threeridge' mussel (one of the Unionidae), which is currently extant in the North Sulphur River (though not common).  I have found fairly large concentrations of these in some of the Late Pleistocene/Early Holocene sediments near the Hwy.24 bridge.  The smaller, smoother ones may be Lampsilis radiata, another member of the Unionidae which is also locally common in Late Pleistocene/Holocene sediments on the NSR.  Shells of this mussel are also relatively abundant in certain areas.  

 

Back in the 1980, a friend of mine and I found a largely-complete skeleton of Bison antiquus resting on a layer of both of these mussels in the bank of the NSR close to the Hwy.24 bridge.  The late Chuck Finsley of the Dallas Museum of Natural History (now the Perot Museum) submitted them to one of his experts who identified them.  Apparently they were among the favorite mussels used for food by the Native Americans who used to inhabit the area.

 

-Joe

Thank you Joe. That info is very informative at a number of levels.

I’m not a bivalve person, but I can appreciate the beauty of the shell.

 

@Peat Burns Thanks for the info. Very interesting that they are so endangered and protected there.

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doushantuo

Haas(Die Unioniden):

 

 

specicgghkkitopugyytykkanguujjjiidp88humb.jpg

some unionids with more unusual shapes for the group:

 

 

 

 

 

 

specicgghkkitopugyeytykkanguujjjiidp88humb.jpg

Unionids have great filtering capacity  and are heavily monitored because of their inportance in keeping rivers and lakes clean.

Hence the protection.

Because of their ecological preferences,they are great proxies for the water quaility of the dulcaquicole (lit."freshwater"/("non-marine")environment.

I can wholeheartedly recommend this:

 

specicgghkkitopugyeytykkanguujjjiidp88humb.jpg

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KimTexan

Regarding the ones with ridges: I’m not sure where you start counting ridges. Mine have more than 3 ridges. There is a Fiveridge one, the Coosa Fiveridge, Amblema elliottii, which use to be called Amblema plicata perplicata. 

Below is the most complete one I found. I’d say it is definitely not the plicata, but it most likely is of the same genus.

DFADD911-8145-4F27-B382-C02308314366.thumb.jpeg.147ac1b031685d8d14c44846cbccb347.jpeg

I think I could have more than one species of them, but for all I know the differences I see could be attributed to dimorphism or juvenile vs adult specimens. I know nothing about Pelecypoda ID. (I can’t remember if the class is italicized. My taxonomy class was close to 30 yrs ago).

 

I’m trying to learn about the ID of most all of the fossils I find (some of which may be modern). I started making the attempt last Fall, 2017. It is slow going, but I am making a sincere effort to learn. I’ve got a biology and clinical medicine background, which helps a little, but I have a long way to go. I truly appreciate your insight and invite any tutorial and educational comments, guidance and direction you may have to offer.

 

This is the Pelecypoda fauna list I have from the “Fossil Collector’s Guidebook to the North Sulfur River” from the “Occassionsl Papers of the Dallas Paleontological Society, Vol. 4.”

878F8509-116B-4E49-A851-59FF37584E14.thumb.jpeg.0661d43c55dfafd0da21e63e02b104a4.jpeg

Maybe some of you who are familiar with the names listed may be able to associate them with the 2 clams in question, if they are fossils. If they’re not fossils then they definitely wouldn’t be in the list. However not being in the list doesn’t automatically exclude them from being fossils either.

 

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MeargleSchmeargl

I say MAYBE modern, but it's really hard to be certain with some shells, as fossils can look almost identical to recent ones (particularly Mussels). 

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Plax
2 hours ago, KimTexan said:

 

 

Maybe some of you who are familiar with the names listed may be able to associate them with the 2 clams in question, if they are fossils. If they’re not fossils then they definitely wouldn’t be in the list. However not being in the list doesn’t automatically exclude them from being fossils either.

 

the list is cretaceous and your clams are Pleistocene or Modern right? Most modern mollusks have representatives that go back at least to the Pleistocene.

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abyssunder

They are too shiny below the external degraded layer(s), in my opinion. :headscratch:

 

" The slow dissolution of these shells releasing calcium carbonate into the water raised the water's pH high enough to prevent the eggshell fragments from dissolving before they could be fossilized. " - Wikipedia

 

 

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Coco
16 hours ago, KimTexan said:

(I can’t remember if the class is italicized. My taxonomy class was close to 30 yrs ago).

No, class doesn't need italicized, only genus and species need ;)

 

Coco

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fifbrindacier

I agree with @abyssunder.

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Plax
9 hours ago, abyssunder said:

They are too shiny below the external degraded layer(s), in my opinion. :headscratch:

 

" The slow dissolution of these shells releasing calcium carbonate into the water raised the water's pH high enough to prevent the eggshell fragments from dissolving before they could be fossilized. " - Wikipedia

 

 

I don't understand what this is in reference to? Perhaps I didn't read back far enough.:(

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Peat Burns
1 hour ago, Plax said:

I don't understand what this is in reference to? Perhaps I didn't read back far enough.:(

I had same question.   I wonder if this relates to the theory that the presence of mollusks is thought to be a factor in buffering deposits with dinosaur eggs, helping to prevent them from dissolving and thus contributing to their preservation.  Interesting, but wondering how it relates to the thread.

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Plax

They made mother of pearl buttons out of fresh water clams (or mussels if you prefer) for a few centuries. The keratinous outer layer was buffed or ground off before the buttons were cut. To me Kim's shells look like old and perhaps Pleistocene examples with the outer layer decomposed baring the nacreous shell within.

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