Bivalve in Lincoln Creek concretion

[winnph]

I've been busy whacking concretions today (ok not so much whacking as gently knocking around and around until they give way), and this is the first one where it contained something that I suspect can be identified.

 

Anyone know what bivalve this is? It's from the middle of the formation, so I think that means Lower Zemorrian? At least that's what it was called in the 1960s when the relevant report was published, I dunno if it's been standardized to some other designation since then. The shell measures 3cm across.

[winnph]

Also notice that small circular fossil below the main shell that looks like a much smaller shell or something... I'm not sure what that is! Here's a closer photo.

[caldigger]

That was a nice clean break/split. You should feel good about that one. 

[winnph]

2 hours ago, caldigger said:

That was a nice clean break/split. You should feel good about that one. 

 

Sure do! I've had pretty good luck with the concretions from this trip splitting nicely, and this one in particular was lucky because I was actually trying to split it the other way. The two immediately before it were jellyfish, and this one looked almost the same shape, so I was trying to split it vertically to show a jellyfish cross section. Goes to show you should never assume your concretion is anything in particular!

 

The thread for this trip is here in case anyone is curious about the other finds: 

 

[Plax]

had to look up Zemorrian. Local stage names can sure be confusing. So the stage is Oligocene to earliest Miocene and your specimen being from the lower part is Oligocene. I'd google "Oligocene bivalves (or pelecypods), puget sound" and see what you get.

[winnph]

13 minutes ago, Plax said:

had to look up Zemorrian. Local stage names can sure be confusing. So the stage is Oligocene to earliest Miocene and your specimen being from the lower part is Oligocene. I'd google "Oligocene bivalves (or pelecypods), puget sound" and see what you get.

Thanks! It's from the southern Olympic peninsula, not around Puget Sound, but thank you for doing the legwork on figuring out what Zemorrian means! I'll do some more searching.

 

Edit: Didn't find anything similar looking, but did find this helpful chart in a report on different bivalve species on the Olympic peninsula.

[Max-fossils]

https://www.researchgate.net/publication/276295388_Fossil_Vesicomyid_Bivalves_from_the_North_Pacific_Region

If you search up "Lincoln" in the search bar (Ctrl + F on Windows), there's a bit of info on the Lincoln Creek Formation. There, it seems like three species are mentioned as possibilities for your shell: Archivesica knapptonensis, Cryptolucina sp and (maybe) Pliocardia sp.

Which one of the three it is, I can't tell... the hinge isn't visible on your specimen, and that makes bivalve determination very difficult  

 

Very cool find though! I love it!  

 

Max

[winnph]

Thanks! I bet with the proper tools the hinge could be revealed! I lack the proper tools, but maybe some day...

 

4 minutes ago, Max-fossils said:

https://www.researchgate.net/publication/276295388_Fossil_Vesicomyid_Bivalves_from_the_North_Pacific_Region

If you search up "Lincoln" in the search bar (Ctrl + F on Windows), there's a bit of info on the Lincoln Creek Formation. There, it seems like three species are mentioned as possibilities for your shell: Archivesica knapptonensis, Cryptolucina sp and (maybe) Pliocardia sp.

Which one of the three it is, I can't tell... the hinge isn't visible on your specimen, and that makes bivalve determination very difficult  

 

Very cool find though! I love it!  

 

Max

 

[Max-fossils]

Just now, winnph said:

I bet with the proper tools the hinge could be revealed! I lack the proper tools, but maybe some day..

I know the feeling only too well...