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Tamiami bivalves help needed


Plantguy

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Well so much for getting distracted again...Uggh! I need to pay attention..Anyways, I just realized I created an earlier thread for a gastropod that I was labeling as a bivalve.oops..I also do need help with actual bivalve IDs....both are from APAC spoils Sarasota County.  Possibly Beds 10 or 11 lower Tamiami formation. Thinking the first one is a Chama. Matrix removal has been a bear on these..

5bb01eeec565c_Chamaunknownpanorama.thumb.jpg.06530c750f1174b4ba93fcad195e1596.jpg

 

And the 2nd I was thinking it might be Marvacrassatella but thats just a guess. I'm going to consolidate the exterior hopefully this week and then separate the valves to get a look at the scar/hinge area if they can be separated. 

5bb01fca8b4de_PossibleMarvacrassatella.thumb.jpg.ba8ca3d98981b1104d97140c53193054.jpg

Thanks for any help/confirmation. 

Regards, Chris 

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Thanks for sharing, nice bivs!

Sorry, but can not help, I am always at a loss with bivs myself...

Franz Bernhard

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I think @MikeR will be able to help with identifications...

 

@Max-fossils is also a fan of bivalves... (I am, too, but I'm not good at identifications :P)

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Very nice shells!

The second one is probably Eucrassatella meridionalis. You were on the right lines :) LINK

The first ones definitely look like Chama's, but which species I'm not so sure... I'm gonna take a guess and say the left one is Chama corticosa and the right one C. emmonsi.

 

Did you find these yourself?

 

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2 hours ago, Monica said:

@Max-fossils is also a fan of bivalves... (I am, too, but I'm not good at identifications :P)

Thanks for the tag; probably would've missed these beauties otherwise :D 

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Hi Chris

 

On the left is Chama conregata Conrad, 1833 found in all Southeastern US Upper Pliocene deposits from Virginia to South Florida.  The other is Eucrassatella meridionalis (Dall, 1900) also found in the Jackson Bluff Formation in the Florida panhandle.

 

Mike

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4 hours ago, MikeR said:

On the left is Chama conregata Conrad, 1833 found in all Southeastern US Upper Pliocene deposits from Virginia to South Florida.

Is this for both Chama shells or only for the left one?

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18 minutes ago, Max-fossils said:

Is this for both Chama shells or only for the left one?

 

For both.  One is an upper valve the other the lower.

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38 minutes ago, MikeR said:

 

For both.  One is an upper valve the other the lower.

Ok that makes sense, thanks.

Just for me to learn more: how can you tell the different Chama species apart? What is it (morphologically speaking) that made you say that these are C. conregata and not C. corticosa or C. emmonsi?

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On 9/30/2018 at 3:13 PM, Max-fossils said:

Ok that makes sense, thanks.

Just for me to learn more: how can you tell the different Chama species apart? What is it (morphologically speaking) that made you say that these are C. conregata and not C. corticosa or C. emmonsi?

 

Although all three have similar characteristics, once you know what to look for it can be quite easy to tell them apart.  The attached valve is the large valve of the two which attaches to a hard surface such as a rock or another shell.  If it bends clockwise (to the right) it is Chama congregata.  Both Chama corticosa and C. emmonsi bend counter-clockwise (to the left). C. emmonsi can be differentiated by its squarish shape and has an indentation along the lower margin of the shell.

 

5bb157cecad4b_MR14134-1151.thumb.jpg.cba054c72ec2ba576e7098ecbf2e8c13.jpg 5bb157cfb6c4a_MR14135-1151.thumb.jpg.2a2c7a229bcc839854a18e5be0cd51ae.jpg 5bb157cdbfe90_MR1121-92.thumb.jpg.062657f288148dfdde5f3310b8e693d1.jpg

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You all are awesome! Thanks again for the comments/help and ID's and discussion...I need to go look at my other Chama's---didnt ever notice bend orientations---probably should have..gonna be neat to see a bunch of them next to each other...they were surface finds from years ago that are in different places/drawers at the moment. Good stuff---thank you. 

@FranzBernhard, @Monica, @Max-fossils, @MikeR

Regards, Chris 

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17 hours ago, MikeR said:

 

Although all three have similar characteristics, once you know what to look for it can be quite easy to tell them apart.  The attached valve is the large valve of the two which attaches to a hard surface such as a rock or another shell.  If it bends counter-clockwise (to the right) it is Chama congregata.  Both Chama corticosa and C. emmonsi bend clockwise (to the left). C. emmonsi can be differentiated by its squarish shape and has an indentation along the lower margin of the shell.

 

5bb157cecad4b_MR14134-1151.thumb.jpg.cba054c72ec2ba576e7098ecbf2e8c13.jpg 5bb157cfb6c4a_MR14135-1151.thumb.jpg.2a2c7a229bcc839854a18e5be0cd51ae.jpg 5bb157cdbfe90_MR1121-92.thumb.jpg.062657f288148dfdde5f3310b8e693d1.jpg

Thanks for the explanation, that's helpful! 

So the orientation of the shell can be a determining factor for the Chama, similarly to how sinistral/dextral shells are sometimes the main criteria in gastropods. Very interesting!

It's true that it's the kind of stuff you never think about, but once you know it it's so obvious. 

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2 hours ago, Max-fossils said:

Thanks for the explanation, that's helpful! 

So the orientation of the shell can be a determining factor for the Chama, similarly to how sinistral/dextral shells are sometimes the main criteria in gastropods. Very interesting!

It's true that it's the kind of stuff you never think about, but once you know it it's so obvious. 

Exactly.  Its encoded within the organism's DNA.

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