Need help identifying clam shell maybe? SOLVED: LIKELY EXOGYRA OYSTER

[PSchleis]

Ok, another new one for me today. I picked up one at Myrtle Beach, SC because it looked interesting, then found a second almost identical one. Now I'm thinking it's something worth knowing!

 

It's dense and heavy. The top has a gray metallic sheen to it. Both of them have a middle circular area that looks rusty, and as if something had been attached there and pulled off.

 

The back looks completely different. Where the front is smooth and shiny, the backside is rather dull. It is comprised of layers, and they layers come together in a knobby area at one end (again, as if perhaps it had been connected to something.)

 

Overall, it really looks like a kind of clam shell to me, but the metallic sheen, rusty circle and layered interior don't look like any clam I've ever seen.

Thank you again!

- Paula

 

Edited January 6, 2019 by PSchleis
added solved to title

[ynot]

Last couple of pictures look like some type of oyster (?).

[Herb]

looks like an oyster operculum

[Fossildude19]

It looks similar to the Exogyra  costata that are found in Big Brook, in NJ. 

 

Photo from HERE. 

[Ludwigia]

I'll go along with Herb. It's definitely oyster at any rate.

[Pemphix]

+1 for oyster

[Rockwood]

5 hours ago, Herb said:

operculum

Actually the correct term, or used to express the asymmetrical concept ?

[Johannes]

43 minutes ago, Rockwood said:

Actually the correct term, or used to express the asymmetrical concept ?

I guess the last one, to avoid the discussion left valve/ right valve (a question paleontology lecturers usually badger their students with...)

 

Btw.: it is the right valve....

[PSchleis]

Thank you, everyone. This site is such an incredibly wonderful resource. And now I have a new fossil for my small-but-growing collection

[FossilDAWG]

Tim is correct, it is an Exogyra.

 

Don

[SailingAlongToo]

54 minutes ago, FossilDAWG said:

Tim is correct, it is an Exogyra.

 

Don

If it is an Exogyra, then they must be dredging thru a Cretaceous layer. When we were there in early October they were clearly dredging thru the SC equivalent of the Pungo River Formation (middle Miocene), as evidenced by the mollusks and shark teeth being deposited on the beach.

[Johannes]

14 minutes ago, SailingAlongToo said:

If it is an Exogyra, then they must be dredging thru a Cretaceous layer. When we were there in early October they were clearly dredging thru the SC equivalent of the Pungo River Formation (middle Miocene), as evidenced by the mollusks and shark teeth being deposited on the beach.

I guess the genus name Exogyra is used here as a waste-bucket for "an unknown oyster I want to label with a more professional sounding name"?

[SailingAlongToo]

1 hour ago, Johannes said:

I guess the genus name Exogyra is used here as a waste-bucket for "an unknown oyster I want to label with a more professional sounding name"?

 

On the contrary, Exogyra is the actual Genus name for this specimen.

[FossilDAWG]

2 hours ago, Johannes said:

I guess the genus name Exogyra is used here as a waste-bucket for "an unknown oyster I want to label with a more professional sounding name"?

You are way out of line.  There is no excuse for such an insulting comment.

Exogyra is a common fossil along the shore at Myrtle Beach.  I have collected many specimens, as well as other distinctive Cretaceous taxa including Squalicorax and Hardouinia kellumi.  Offshore dredging for beach replenishment often brings up PeeDee Formation material.  Other formations are sometimes encountered, so Miocene to Pleistocene fossils may also be encountered.  However the morphology of Exogyra is distinctive and is quite unlike any of the other oysters that might be encountered at Myrtle Beach.

 

Don

[Johannes]

35 minutes ago, SailingAlongToo said:

 

On the contrary, Exogyra is the actual Genus name for this specimen.

Why not Crassostrea, Ostrea or Pycnodonte (which are, in my opinion more probably for serveral reasons)?  Oyster taxonomy is tricky, esp. with only right valves, so I would be really happy if you can explain why you assign the first shown oyster to Exogyra genus! Thank you very much in advance!

 

@FossilDAWG: edit: sorry, I don`t want to insult a person. I only know that a lot of so asigned oysters in many collections finally do not belong to Exogyra. But the species is so heteromorph, that the morphology of the right valve is maybe not so distictive to use. But, if I have insulted you questioning your determination or your local site  knowledge, my apologies!

[MikeR]

16 minutes ago, Johannes said:

Why not Crassostrea, Ostrea or Pycnodonte (which are, in my opinion more probably for serveral reasons)?  Oyster taxonomy is tricky, esp. with only right valves, so I would be really happy if you can explain why you assign the first shown oyster to Exogyra genus! Thank you very much in advance!

 

Exogyra is correct because those of us who collect the Upper Cretaceous in the Southeastern US see it at almost all sites and based upon the species can date any outcrop as Santonian, Campanian, or Maastrichtian.  Don is correct about the Peedee which is frequently encountered in dredging operations not only on the coast but also the Intercoastal Waterway at Mrytle Beach.  The Peedee is Maastrichtian so more than likely it is Exogra costata.  LINK

[Misha]

Definitely agree with everyone above, here are a few that I have found myself in NJ.

[erose]

At least one of those, the one with the distinct "layers" is absolutely the upper valve of the oyster genus Exogyra. There are a number of possible species that would have very similar valves. We would need the larger lower valve to make an ID. Not sure what is most common in the Peedee.

 

Exogyra is one of the most common oysters of the Cretaceous. The genus evolved a variety of species over time and they can act as index fossils for the various stages of the Cretaceous. 

 

Not sure why everyone got so hot and bothered (unless they were being facetious) by your catch bucket comment. Here in Texas every weird thing is a "rudist" until proven otherwise...much to the detriment of that poor step-child group of bivalves.

[FossilDAWG]

22 minutes ago, erose said:

Not sure why everyone got so hot and bothered (unless they were being facetious) by your catch bucket comment. 

What I did not appreciate was the insinuation that I was trying to come off as sounding "more professional" by offering an unfounded "waste bucket" ID.

 

Don

[erose]

20 minutes ago, FossilDAWG said:

What I did not appreciate was the insinuation that I was trying to come off as sounding "more professional" by offering an unfounded "waste bucket" ID.

 

Don

Sorry Don, Still didn't get any of that from his postings. You're a moderator and that reaction surprised me. That's all.

 

But I think everyone made it clear that it wasn't your intention and Johannes just needed more explanation/confirmation.

 

[Auspex]

21 minutes ago, FossilDAWG said:

What I did not appreciate was the insinuation that I was trying to come off as sounding "more professional" by offering an unfounded "waste bucket" ID.

 

Don

It's a shock to the system when you helpfully offer an informative answer, and feel like it was thrown back in your face.

[SailingAlongToo]

1 hour ago, erose said:

At least one of those, the one with the distinct "layers" is absolutely the upper valve of the oyster genus Exogyra. There are a number of possible species that would have very similar valves. We would need the larger lower valve to make an ID. Not sure what is most common in the Peedee.

 

Exogyra is one of the most common oysters of the Cretaceous. The genus evolved a variety of species over time and they can act as index fossils for the various stages of the Cretaceous. 

 

Not sure why everyone got so hot and bothered (unless they were being facetious) by your catch bucket comment. Here in Texas every weird thing is a "rudist" until proven otherwise...much to the detriment of that poor step-child group of bivalves.

@erose

For the record, I like my oysters raw, steamed and fried. A dozen of each, in that order, followed by a couple of oyster shooters for dessert and you have a perfect meal!