A bunch of different Glycymeris

[Max-fossils]

Hi all,

 

So, here are a bunch of fossil bittersweet clams (Glycymeris) from different locations. So far they are all labeled as "Glycymeris" (which I'm pretty sure is correct). But I would really like to put a species name on each of them. Therefore I am reaching out to you all, because hopefully you will be able to help me sort this out!

 

1) Glycymeris from Westerschelde, Netherlands; from the late Pliocene (2.5 million years old). I'm thinking G. radiolyrata, but I'm not sure...

 

 

2) Glycymeris from Westerschelde, Netherlands; from the late Pliocene (2.5 million years old). G. obovata maybe? Or G. variabilis???

[Max-fossils]

3) A small one from Oosterzele, Belgium. From the Lede Sand formation, Lutetian, early Eocene (45 mya). Got no clue for this one...

[Max-fossils]

4) A bittersweet clam from Kaloot, Zeeland, Netherlands. From the Miocene-Pliocene. Not sure about this one either...

5) And finally, one from the Antwerp area, Belgium. From the Miocene-Pliocene. Could it be G. obovata??? 

 

Please help me with this intricate puzzle! 

 

Best regards,

 

Max

[Spinosaurus]

these are a few nice ones

[Max-fossils]

34 minutes ago, Spinosaurus said:

these are a few nice ones

Thanks 

The first two were given to me when I joined the WTKG. The second one I got in an old collection. The last two are my personal finds.

[abyssunder]

According to Moerdijk, Peter W., & Freddy A.D. van Nieulande. 1995. Glycymeris (Glycymeris) radiolyrata sp. nov. (Mollusca, Bivalvia, Glycymerididae) from the Pliocene of the North Sea Basin. — Contr. Tert. Quatern. Geol., 32(1-3): 3-17, the distinguishing characters of G. variabilis and G. radiolyrata are as follows:

 

G. variabilis invariably shows distinct grooves on the ligamental area, the external ornament consists of a very fine reticulate sculpture, tending .to efface rapidly, and the shell is generally markedly inequilateral, being drawn out posteriorly. In juvenile specimens the umbo is quite prominent.

G. radiolyrata has a principally smooth ligamental area and a distinctive external ornament consisting of welldeveloped radial elements especially near the umbones; towards the shell margin the reticulate ornament is less fine and more irregular. The shell is almost equilateral and circular in outline. The umbo of juvenile specimens is not prominent; their external ornament consists of coarse radial elements (Fig. 1) overprinted by concentric grooves.

The ornament in juvenile G. variabilis is decidedly finer.

 

here is your older topic:

Also, here is a more recent document which may help you: Moerdijk, Peter W. & Freddy. A.D. van Nieulande. 2000. Revision of Pliocene Glycymerididae (Mollusca, Bivalvia) from the North Sea Basin. - Contr. Tert. Quatern. Geol., 3(1-2): 3-21

[Shamalama]

I recall finding something like those in the Miocene sediments of Calvert Cliffs, MD.

[Max-fossils]

1 hour ago, Shamalama said:

I recall finding something like those in the Miocene sediments of Calvert Cliffs, MD.

Doesn't surprise me 

The bittersweet clams are a very widespread family! 

 

1 hour ago, abyssunder said:

According to Moerdijk, Peter W., & Freddy A.D. van Nieulande. 1995. Glycymeris (Glycymeris) radiolyrata sp. nov. (Mollusca, Bivalvia, Glycymerididae) from the Pliocene of the North Sea Basin. — Contr. Tert. Quatern. Geol., 32(1-3): 3-17, the distinguishing characters of G. variabilis and G. radiolyrata are as follows:

 

G. variabilis invariably shows distinct grooves on the ligamental area, the external ornament consists of a very fine reticulate sculpture, tending .to efface rapidly, and the shell is generally markedly inequilateral, being drawn out posteriorly. In juvenile specimens the umbo is quite prominent.

G. radiolyrata has a principally smooth ligamental area and a distinctive external ornament consisting of welldeveloped radial elements especially near the umbones; towards the shell margin the reticulate ornament is less fine and more irregular. The shell is almost equilateral and circular in outline. The umbo of juvenile specimens is not prominent; their external ornament consists of coarse radial elements (Fig. 1) overprinted by concentric grooves.

The ornament in juvenile G. variabilis is decidedly finer.

 

here is your older topic:

Also, here is a more recent document which may help you: Moerdijk, Peter W. & Freddy. A.D. van Nieulande. 2000. Revision of Pliocene Glycymerididae (Mollusca, Bivalvia) from the North Sea Basin. - Contr. Tert. Quatern. Geol., 3(1-2): 3-21

Thanks a lot! 

Ah, yup, I have a lot of different Glycymeris  I forgot about this topic... re-reading it was quite helpful.

 

For the other people, here are the two pictures @abyssunder posted on the older topic:

PLATE 2
Glycymeris (Glycymeris) radiolyrata sp. nov.
Fig. 1. Right valve, paratype (RGM 393 824, leg. M. Vervoenen), Lillo Formation, Oorderen Member, Pliocene (Scaldisian), construction pit Beveren tunnel at Kallo (Belgium), x c. 1.25; c - hinge; d - detail of external ornament.
Fig. 2. Juvenile left valve (RGD Coll. Mol.673), Pliocene, borehole Nijmegen (’Midden-Plioceen’), x c. 10.

 

PLATE 4
Fig. 1. Glycymeris (Glycymeris) variabilis (J. de C. Sowerby, 1824), right valve (RGM 393 826, leg. M. Vervoenen), Lillo Formation, Oorderen Member (level with Angulus benedeni), Pliocene (Scaldisian), construction pit Beveren tunnel at Kallo (Belgium), x 1.7; c - detail of external ornament; d - hinge.

 

 

Looking at the paper that you just gave, I think that these are the IDs for mine:

1) Glycymeris (Chevronia) variabilis

2) Glycymeris (Glycymeris) radiolyrata exaggerata

3) Glycymeris (G.) radiolyrata pseudodeshayesi

4) Glycymeris (Chevronia) turonica

5) Glycymeris (Glycymeris) radiolyrata exaggerata

 

Do you agree? 

 

Thanks again!

 

Max

[abyssunder]

You could be right, but to be sure, try contacting the above authors, they'll know exactly how to assign them to the species.

Nice finds, btw!

[Max-fossils]

21 hours ago, abyssunder said:

You could be right, but to be sure, try contacting the above authors, they'll know exactly how to assign them to the species.

Nice finds, btw!

Thanks! As I said before, only #4 and #5 are personal finds. But in total I found a lot more (I just didn't display them because they were very similar to the ones I just posted), including some big ones in the Antwerp area.

 

I'll try contacting Freddy van Nieulande, he will surely be able to help me. Thanks again for the help