Shell Identification (Brachiopod)

[briana]

Hi there,

 

I believe I found a brachiopod fossil (pedicle valve). I'm hoping for some help identifying it more specifically - family, genus, or species?

 

It was buried a few feet deep on an eroding, sandy hillside about 30 meters above sea level. The hill is about 2 kilometers from an inlet around the Puget Sound region of Washington state (glacial till). Please see attached photos. It looks like there might be other shells fossilized within the cavity. Please let me know if you need more info/different angle photos. Thank you in advance for any help!

 

[Misha]

Interesting find, looks like a bivalve rather than brachiopod to me though

[Ludwigia]

I agree with Misha. Brachiopods show a bilateral symmetry. This shell does not show that.

[briana]

1 hour ago, Misha said:

Interesting find, looks like a bivalve rather than brachiopod to me though

 

1 hour ago, Ludwigia said:

I agree with Misha. Brachiopods show a bilateral symmetry. This shell does not show that.

 

Thank you for your responses!

 

I thought it was a bivalve when I first found it, but the hole in the back confused me. A marine biology professor told me the hole meant it was a brachiopod, so I went with that. The symmetry issue is helpful.

 

If it is not a brachiopod, what could cause a hole like that? What bivalve could it be? I'm wondering if uneven wear on the specimen is making it look less symmetrical, so I'm still not ruling brachiopod out. I've been searching for online resources about bivalve/brachiopod fossils in this area but haven't seen anything that is a clear match. 

 

 

[BobWill]

I don't recognize the fossil but it resembles the scallops I find. The hole may be a boring but seems too large for a foramen. There seems to be several pieces of other shells laying inside the valve, visible on the back side.

[JohnJ]

@MikeR

 

[Misha]

The pedicle opening on brachiopods would usually be a lot more round, even and symmetrical than what you see here. The hole could've simply been caused by weathering of the fossil, many modern bivalve shells also tend to get holes near the beak

[Coco]

Hi,

 

This shell is very worn, so I think the hole is caused by erosion. If it was a brachiopod, the hole would be proportionally smaller, same for a predation hole.

 

Coco

[briana]

12 hours ago, Misha said:

The pedicle opening on brachiopods would usually be a lot more round, even and symmetrical than what you see here. The hole could've simply been caused by weathering of the fossil, many modern bivalve shells also tend to get holes near the beak

 

9 hours ago, Coco said:

Hi,

 

This shell is very worn, so I think the hole is caused by erosion. If it was a brachiopod, the hole would be proportionally smaller, same for a predation hole.

 

Coco

 

Ah, this makes sense! Maybe the hole even started as predation, but also eroded and became larger/more irregular? Could it be cockle?

[FossilDAWG]

I agree with some sort of Cardium (cockle) or relative.  There are some Eocene and Oligocene deposits around Puget Sound that produce fossils like this.  Some of those deposits formed near shore and many of the fossils are wave-worn like your specimen.

 

I'm a little surprised that a marine biologist could misidentify this as a brachiopod.  Maybe more involved in plankton or algae I guess.

 

Don

 

[MikeR]

19 hours ago, JohnJ said:

@MikeR

 

Bivalve.  My best guess is Cardium as well.  

[briana]

On 9/27/2022 at 10:29 AM, FossilDAWG said:

I'm a little surprised that a marine biologist could misidentify this as a brachiopod.  Maybe more involved in plankton or algae I guess.

 

 

I am going to needle him about it, for sure. Ha!

 

Thank you everyone for taking the time to look and for such fast replies. I think Cardium is pointing me in the right direction! I appreciate the help very much.