California bivalve ID

[Misha]

Hi everyone,

I have recently received this fossil as part of a trade with @Huntonia the bivalve comes from California, but other than that I have no more information.

I am guessing it is from somewhere in the cenozoic which is an era that I am not highly familiar with.

Any info would be great,

Thank you. 

[Misha]

The last picture is from the other side where not munch of the large shell is left but there are two others.

[Fossildude19]

@caldigger  @siteseer

[caldigger]

Definately not in my field of knowledge.

That's why I always defer bivalve IDs to @Max-fossils

Although the type of matrix seems like it may be from Northern California. 

@RJB may know this one. If I remember correctly he said he collected bivalves from N.Calif. 

[siteseer]

4 hours ago, Fossildude19 said:

@caldigger  @siteseer

 

Yeah, without even a general area, it's impossible to say but it does resemble the preservation of some shells in the Purisima Formation, Santa Cruz County.  There are sites farther north with Pliocene shells too.  Someone more familiar with mollusks might have a better idea but I would say it might be a Clinocardium.

 

Yeah, I would say show it to RJB too.

 

Jess

[Max-fossils]

I am very unfamiliar with Californian shells, and generally not very good at identifying shells in matrix. 

But, assuming that @siteseer's assumption of Purisima Formation is correct, googling for 'Purisima Formation fossils' delivers some results, including this one here: LINK

In here it says: 

Quote

Abundant bivalve taxa are: Anadara trilineata, Clinocardium meekianum, Macoma sp., Protothaca staleyi, and Tresus pajaroanus.

Macoma and Tresus are definitely not correct for your specimen, and I don't think Anadara or Protothaca fit really well either. 

That leaves Clinocardium: while the concentric ridges don't fit very well IMO, the shape does fit well (quite a high umbo, umbo poiting to a side, bit bulbous, etc), meaning Jess' guess was probably accurate  (The different concentric ridges may be due to erosion; Cardiidae shells always erode weirdly I've noticed)

 That being said, there are obviously other rarer species in the formation, and perhaps one that fits better, but seeing that these are the most abundant taxa makes it likely yours is a Clinocardium. 

 

So, if you wanna update your label from "Shell, California", I would do this:

• Clinocardium meekianum (?)
• Purisima Formation, Pliocene (?)
• Capitola Beach, Santa Cruz (?), CA, USA 

The question marks are just to be safe, as it isn't sure that this is the correct info. 

 

[FossilDAWG]

@MikeR is knowledgeable about West Coast molluscs, as well as the South East.

 

Don

[RJB]

  Looks very much like a worn Clinocardium,, but something about the shape says Anadara?  Just not sure. 

 

RB

[Misha]

1 hour ago, RJB said:

  Looks very much like a worn Clinocardium,, but something about the shape says Anadara?  Just not sure. 

 

RB

I also have this picture if it helps

I can get more later if that would help

[RJB]

No help. Too worn.   Try and compair with this Clinocardium.  Only picture I have of this clam.

 

RB

[Misha]

29 minutes ago, RJB said:

No help. Too worn.   Try and compair with this Clinocardium.  Only picture I have of this clam.

 

RB

The general shape does seem accurate