Brachiopod or Bivalve?

[Darbi]

Kiowa formation and Albian. Approximately 1.3cm long and its quite flat and thin. Not sure if it's brachiopod, more specifically a lingula brachiopod, or a bivalve. Unfortunately the umbo is missing so I'm not sure if it's symmetrical or not. I'm leaning more on bivalve but I would like to read your opinion. What's the lowest taxonomy level you can identify?

 

[Creek - Don]

inceromous clam.  There are brachiopods in Kansas, but nothing like this.  

[Pemphix]

1 hour ago, Creek - Don said:

inceromous clam.  There are brachiopods in Kansas, but nothing like this.  

+ 1 for Inoceramus = Clam

https://www.cretaceousatlas.org/species/inoceramus-labiatus/

https://www.sciencedirect.com/science/article/pii/S0195667115300987

https://books.google.de/books?id=D5pTRDcJUc8C&pg=PA36&lpg=PA36&dq=kansas+inoceramus+alb&source=bl&ots=AWc_magB8O&sig=ACfU3U0Xn5WcIv5aw7Gzae48G7K48OWciA&hl=de&sa=X&ved=2ahUKEwj7qK7SjO_pAhWFDewKHdjeD3EQ6AEwBnoECAcQAQ#v=onepage&q=kansas inoceramus alb&f=false

 

 

[Al Dente]

It looks phosphatic to me. I think it is a lingulid brachiopod.

[Ludwigia]

I'll go along with Al Dente.

[FossilDAWG]

I agree with lingulid brachiopod.

 

Don

[westcoast]

Looks like a mytilid bivalve to me.

[Darbi]

On 6/7/2020 at 1:12 AM, Creek - Don said:

inceromous clam.  There are brachiopods in Kansas, but nothing like this.  

 

On 6/7/2020 at 2:46 AM, Pemphix said:

+ 1 for Inoceramus = Clam

https://www.cretaceousatlas.org/species/inoceramus-labiatus/

https://www.sciencedirect.com/science/article/pii/S0195667115300987

https://books.google.de/books?id=D5pTRDcJUc8C&pg=PA36&lpg=PA36&dq=kansas+inoceramus+alb&source=bl&ots=AWc_magB8O&sig=ACfU3U0Xn5WcIv5aw7Gzae48G7K48OWciA&hl=de&sa=X&ved=2ahUKEwj7qK7SjO_pAhWFDewKHdjeD3EQ6AEwBnoECAcQAQ#v=onepage&q=kansas inoceramus alb&f=false

 

 

 

On 6/7/2020 at 5:02 AM, Al Dente said:

It looks phosphatic to me. I think it is a lingulid brachiopod.

 

On 6/7/2020 at 6:44 AM, Ludwigia said:

I'll go along with Al Dente.

 

On 6/7/2020 at 12:53 PM, FossilDAWG said:

I agree with lingulid brachiopod.

 

Don

 

On 6/7/2020 at 4:19 PM, westcoast said:

Looks like a mytilid bivalve to me.

 

 

Wow, everyone are divided on which one it is. Right now, I'm leaning more toward Inoceramus. My justification: fossilized Inoceramus from Kiowa formation are fairly common while lingulid brachiopods are not. Inoceramus also have prominent, semicircular growth lines, as in pictures shown above.

 

I have never encountered a fossilized juvenile Inoceramus or Inoceramus this small before. I am not familiar with mytilid bivalve from Kiowa, I will have to look into this. I have list of scientific journals on Kiowa formation and its fossils saved on my computer, I have not reviewed them all yet, only a couple of them. I hope to find more descriptions on Inoceramus, lingulid brachiopod, mytilid, and others from Kiowa before I make a solid judgment. Thank you everyone!

[FranzBernhard]

It "looks" asymmetric, so it would be bivalve.

The shell seems nicely preserved, so what do you see in detail: Is the shell prismatic/fibrous or platy/scaly?

Franz Bernhard

[jpc]

Brachiopods and bivalves are both symmertrical.  In bivalves the plane of symmetry runs along the hinge line and between the two shells; each shell is symertrical with the other half of the shell.  In brachiopods, the plane of symmerty runs down the middle of the each shell, going perpendicular to the plane delinaeting the two individual shells.  In the photo of the lingula above, you can see that it can be divided symmetrically down the middle, top to bottom.  That is a brachiopod.  The shell in the original post does not have this, as the concentric circles lean towards one side.  The fossil in question is a clam.  Kiowa Fm... I would vote for Inoceramus.

[Al Dente]

18 minutes ago, jpc said:

Brachiopods and bivalves are both symmertrical.  In bivalves the plane of symmetry runs along the hinge line and between the two shells; each shell is symertrical with the other half of the shell.  In brachiopods, the plane of symmerty runs down the middle of the each shell, going perpendicular to the plane delinaeting the two individual shells.  In the photo of the lingula above, you can see that it can be divided symmetrically down the middle, top to bottom.  That is a brachiopod.  The shell in the original post does not have this, as the concentric circles lean towards one side.  The fossil in question is a clam.  Kiowa Fm... I would vote for Inoceramus.

I think it is symmetrical down the middle, there is more broken off one side than the other. 
 

 

[Al Dente]

Here’s an article on the Kiowa I found online that states “Invertebrate fossils include lingulid brachiopods, which were a very common element of the fossil fauna from the clastic unit”
 

 

[jpc]

45 minutes ago, Al Dente said:

I think it is symmetrical down the middle, there is more broken off one side than the other. 
 

 

Hmmm... if some is missing from the bottom... I could go with that.  Darn, I thought I had solved it.  

[piranha]

40 minutes ago, Al Dente said:

Here’s an article on the Kiowa I found online that states “Invertebrate fossils include lingulid brachiopods, which were a very common element of the fossil fauna from the clastic unit”

 

 

According to this paper the species is: Lingula subspatulata

 

Scott, R.W. 1970

Paleoecology and Paleontology of the Lower Cretaceous Kiowa Formation, Kansas.

The University of Kansas Paleontological Contributions, 52(1):1-94  PDF LINK

[Darbi]

On 6/10/2020 at 10:43 AM, FranzBernhard said:

The shell seems nicely preserved, so what do you see in detail: Is the shell prismatic/fibrous or platy/scaly?

I am not sure what you mean by this. Can you please elaborate?

[Darbi]

On 6/7/2020 at 4:02 AM, Al Dente said:

It looks phosphatic to me.

How do you tell it's phosphatic? I do not know what fossilized phosphatic shell are supposed to look like.

[Darbi]

On 6/10/2020 at 12:09 PM, Al Dente said:

Here’s an article on the Kiowa I found online that states “Invertebrate fossils include lingulid brachiopods, which were a very common element of the fossil fauna from the clastic unit”

Apparently I misremembered from the literature I read, sorry!  Thank you for correcting me. 

Quoting from the literature I was referring to:

 

"OCCURRENCE AND MATERIAL.—TWENHOFEL (1924) reported Lingula fragments in shale and in "Mentor beds." Additional molds and chitino-phosphatic shells are rare in shale, sandstone, and shell conglomerates in central and southern Kansas ranging throughout nearly the entire thickness of the Kiowa. The species ranges from Cenomanian to Maastrichtian in the Western Interior and Gulf Coast."

 

Scott, R.W. 1970

Paleoecology and Paleontology of the Lower Cretaceous Kiowa Formation, Kansas.

The University of Kansas Paleontological Contributions, 52(1):1-94

This is probably where I misremembered or misread from.

 

On 6/10/2020 at 12:03 PM, Al Dente said:

I think it is symmetrical down the middle, there is more broken off one side than the other. 
 

On 6/10/2020 at 12:52 PM, jpc said:

Hmmm... if some is missing from the bottom... I could go with that.  Darn, I thought I had solved it.  

I looked at my specimen again and I think it's symmetrical down the middle. I looked at the edge of both sides:

 

the one where it was more broken off, the internal matrix is more exposed than the other side that is less broken off. That indicates it's most likely symmetrical down the middle. You got me convinced it's most likely a lingulid brachiopod.

 

On 6/10/2020 at 12:54 PM, piranha said:

 

 

According to this paper the species is: Lingula subspatulata

 

Scott, R.W. 1970

Paleoecology and Paleontology of the Lower Cretaceous Kiowa Formation, Kansas.

The University of Kansas Paleontological Contributions, 52(1):1-94  PDF LINK

It's one of a couple literature I read on Kiowa fm. I think it's probably Lingula subspatulata. Thank you!

 

Everybody, thank you for the help! I still have few kilograms of broken matrices from Kiowa, I hope to find more specimens of this same species.

[FranzBernhard]

1 hour ago, Darbi said:

I am not sure what you mean by this. Can you please elaborate?

Fibrous/Prismatic: Fibers or slender "columns" are arranged perpendicular to the shell´s  extension.

Scaly/Platy: Thin plates or sheets are arranged parallel to the shell´s extension.

Here are two pics of Miocene shells (not the best, cobbled together from old pics). Pinnid bivalve to the left, mytilid bivalve to the right.

 

2 hours ago, Darbi said:

How do you tell it's phosphatic?

You can exclude phosphatic with an acid test. If a fragment of a shell bubbles in vinegar or hydrochlorid/muriatic acid (HCl), than it is calcite or aragonite.

Phosphate ("apatite") will dissolve very slowly in HCl, without much bubbling, if any.

Franz Bernhard

[Darbi]

On 6/15/2020 at 12:39 AM, FranzBernhard said:

Fibrous/Prismatic: Fibers or slender "columns" are arranged perpendicular to the shell´s  extension.

Scaly/Platy: Thin plates or sheets are arranged parallel to the shell´s extension.

Here are two pics of Miocene shells (not the best, cobbled together from old pics). Pinnid bivalve to the left, mytilid bivalve to the right.

 

You can exclude phosphatic with an acid test. If a fragment of a shell bubbles in vinegar or hydrochlorid/muriatic acid (HCl), than it is calcite or aragonite.

Phosphate ("apatite") will dissolve very slowly in HCl, without much bubbling, if any.

Franz Bernhard

I can't tell if it's fibrous, even under the 1000x magnification. The shell is thinner than hair. I don't think it's platy or scaly, I don't see this pattern around the broken edges. I added a drop of vinegar on the shell and it didn't bubble after 30 minutes, no visible bubbles under the microscope either. Is it safe to assume it's phosphatic?

[FranzBernhard]

3 hours ago, Darbi said:

I can't tell if it's fibrous, even under the 1000x magnification. The shell is thinner than hair. I don't think it's platy or scaly, I don't see this pattern around the broken edges. I added a drop of vinegar on the shell and it didn't bubble after 30 minutes, no visible bubbles under the microscope either. Is it safe to assume it's phosphatic?

At least the shell is not composed of calciumcarbonate (calcite or aragonite) and by exclusion of other possibilities and the general appearance, phosphatic is extremely highly likely.

Franz Bernhard