Does anyone know what this is please?

[Avis]

Found on the shore in New Jersey or North Carolina. Feels like rough texture stone and is heavy for it’s size. Thanks for any info!Back.Front.

Edited 5 hours ago by Avis
Forgot to add a word in the title.

[Ludwigia]

Looks like a steinkern of a Megalodon bivalve with recent Pholad (boring bivalves) borings and remnants.

[jpc]

Megalodon...?  Isn't that a shark?  

I agree though, that this is what it is.  Really cool... a fossil with modern critters preserved in it.  

[Ludwigia]

38 minutes ago, jpc said:

Megalodon...?  Isn't that a shark? 

 

Yes, it also is, isn't it? Although the shark officially has a small letter at the front since it's a species name given by Agassiz in 1835, whereby the bivalve has a capitalized first letter, since it's a genus name given by Sowerby in 1827.

[paleoflor]

Megalodon (bivalve) - Wikipedia

 

EDIT: In the brief amount of time it took get the Wikipedia link and copy it in here, Roger already replied himself...

Edited 2 hours ago by paleoflor

[Al Dente]

Probably Cucullaea.

[Ludwigia]

3 minutes ago, Al Dente said:

Probably Cucullaea.

On second thought, I think you're correct.

[FossilNerd]

I'm with @jpc. Never knew there was a genus of bivalve named Megalodon. 

 

Learn something new everyday. Thanks Roger! @Ludwigia  

[Fossildude19]

Age range discounts a "Megalodon" bivalve.

[Ludwigia]

2 minutes ago, Fossildude19 said:

Age range discounts a "Megalodon" bivalve.

Yup. I'm not familiar with the stratigraphy in those parts, so I wasn't paying proper attention, although it certainly does look like a Megalodon.

[Family Fun]

Cucullaea was a new one for me, looks it up and I totally agree with the identification.   Love this forum and all the expert opinions..

[FossilDAWG]

There is a fair bit to unpack here.

 

As @Al Dente said, this is more likely to be a Cucullaea.  Megalodon (the bivalve) was a Devonian-Jurassic genus (according to Wikipedia), but it certainly has a similar appearance to Cucullaea.  I think the dentition (hinge line) differs quite a lot though.

 

I was not aware that there is a bivalve genus called Megalodon.  Thanks Roger, I learned something. 

 

However, there is no rule in taxonomy that allows a genus name to be spelled with a small first letter, regardless of who named it.  "Megalodon" would be the only way to spell the genus; "megalodon" would be a colloquial or common name but not a formal scientific name.  The bivalve Megalodon was named (by Sowerby) in 1827, after that the name could not be used for any other animal genus.  The rules of taxonomy state that no two genera within a kingdom (which mollusks and vertebrates certainly are) cannot have the same name.  The shark) was named by Agassiz in 1835, initially as Carcharias megalodon.  Note that "megalodon" was the specific (or "trivial") name, and this does not conflict with the genus name Megalodon.  However Agassiz used Carcharias for sand tiger sharks, and "megalodon" is clearly not a sand tiger, so he later changed the genus to Carcharocles.

 

Isn't taxonomy fun? (Don't answer that!).

 

Don

 

[Mark Kmiecik]

The intended pun, referring to size is understood, by me at least.