Are these all oysters?

[PMA]

Hey,

these pieces were found in the Normandy, France at the Falaises des Vaches Noir near Houlgate. I was wondering if these are all oysters and oysters pieces or if theres also something different?

[Echinoid]

@PMA, could you please post pics of the items in the last photo at different angles?

[PMA]

41 minutes ago, Echinoid said:

@PMA, could you please post pics of the items in the last photo at different angles?

Here are new pics, always 2 of each

[Cowboy Paleontologist]

I know that these two are some sort of Gryphaea which are in fact oysters.  I'm guessing that these are from a Jurassic formation? 

Possibly G. arcuata or G. dilobotes, as these seem to be the most common around the coasts of England and France.

[Ludwigia]

The Gryphaea are G.dilatata. First photo bottom left is a Myophorella. The ones on the right are either Arctostrea or Rastellum, although the experts seem to still be debating about what's what.

[PMA]

5 hours ago, Cowboy Paleontologist said:

I know that these two are some sort of Gryphaea which are in fact oysters.  I'm guessing that these are from a Jurassic formation? 

Possibly G. arcuata or G. dilobotes, as these seem to be the most common around the coasts of England and France.

I don't really know because I got them from friends, but I supposed its Middle Jurassic there. Thanks!

3 hours ago, Ludwigia said:

The Gryphaea are G.dilatata. First photo bottom left is a Myophorella. The ones on the right are either Arctostrea or Rastellum, although the experts seem to still be debating about what's what.

Really helpful, thanks! Arctostrea and Rastellum really look the same.

[elcoincoin]

Hi there

 

First 4 photos : Actinostreon gregaria (lopha gregaria) so yes oyster

photo 5 : myophorella sp so a clam

photo 6 looks like the back side of a gryphaea dilatata so yes oyster

photo 7 and 8 Actinostreon  marshii (lopha marshii) so yes oyster

rest i wont try to id that.

 

10 hours ago, PMA said:

Here are new pics, always 2 of each

 

[Ludwigia]

6 hours ago, elcoincoin said:

 

First 4 photos : Actinostreon gregaria (lopha gregaria) so yes oyster

 

This is what I meant above without going into details. Arctostrea gregaria was reassigned to Actinostreum gregarium according to Koppka & Co. although some paleontologists still use the former name. Actinostreum used to be called Lopha in many cases until someone revised that using the argument that Lopha is modern and not ancient. Cases like this can get confusing for amateur collectors, but it's important to know that different names often mean the same thing.     

 

6 hours ago, elcoincoin said:

 

photo 7 and 8 Actinostreon  marshii (lopha marshii) so yes oyster

 

 You may be right on that. 

[elcoincoin]

6 hours ago, Ludwigia said:

This is what I meant above without going into details. Arctostrea gregaria was reassigned to Actinostreum gregarium according to Koppka & Co. although some paleontologists still use the former name. Actinostreum used to be called Lopha in many cases until someone revised that using the argument that Lopha is modern and not ancient. Cases like this can get confusing for amateur collectors, but it's important to know that different names often mean the same thing.    

 

Hello,

 

This is also true for the other one. we used to call them "trigonia" and now its "myophorella" ( for instance Myophorella clavellata ). Actually, it s even worth because another clam from "les vaches noires" used to be called trigonia and still is : Trigonia elongata