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La Salle County Brachiopod Unknown


minnbuckeye

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Here is a brachiopod that I am completely lacking a guess on its identity. The specimen is from the Bond Formation, LaSalle Limestone, Pennsylvanian, found in LaSalle County, Illinois. It is tiny for the formation's other brachiopods.

 

2022-07-019.thumb.jpg.f9af0294f901ea2747030f64a587dd76.jpg

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  • minnbuckeye changed the title to La Salle County Brachiopod Unknown

Based on: inflated nature, wide hinge line, strong sulcus, weak radial ornamentation, and moderate growth lines, I would call this one of the species of Quadrochonetes.  But that genus is only known from a little later than the Lasalle LS time (middle Missourian) and the overall shape of it might suggest more of a Chonetinella.   The more I stare at the materials developed by the Dallas Paleo Society, the more I lean to Chonetinella.  Both C. flemingi and C. papilioniformis are from the proper age and look similar to yours.  I would have to study the details separating those two more to decide between them.

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@ClearLake Thanks for the research!! I couldn't find anything that was similar. Your suggestion looks like a winner!! I wish I had magnification so it could be exposed better.

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Based on @ClearLake's super informative post, I have sourced the publishing papers of one two species mentioned - I cannot seem to find anything online regarding Chonetinella papilioniformis.

 

From PENNSYLVANIAN BRACHIOPODS OF OHIO by Myron T. Sturgeon and Richard D. Hoar | (core.ac.uk)

 

image.png.ad32cbd87cf2d5088d320a2ca144172b.png

 

Isaac

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~ Isaac; www.isaactfm.com 

 

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See Chonetina papilioniformis 4a - 4f in plate 55.
Newell, N. D. (1934). Some Mid-Pennsylvanian Invertebrates from Kansas and Oklahoma: I. Fusulinidae, Brachiopoda. Journal of Paleontology, 8(4), 422–432. http://www.jstor.org/stable/1298131
 

https://www.jstor.org/stable/1298131?read-now=1&refreqid=excelsior%3Aca1f206ddc8295fbdb79e611f8666add&seq=13#page_scan_tab_contents

 

 

02E2E3AB-F68F-4D24-842A-95BE9450BC9F.jpeg

141C5277-9EB3-4171-9AD7-2C69A22B9136.jpeg

Edited by DPS Ammonite
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My goal is to leave no stone or fossil unturned.   

See my Arizona Paleontology Guide    link  The best single resource for Arizona paleontology anywhere.       

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19 minutes ago, DPS Ammonite said:
See Chonetinella papilioniformis 4a - 4f in plate 55.
Newell, N. D. (1934). Some Mid-Pennsylvanian Invertebrates from Kansas and Oklahoma: I. Fusulinidae, Brachiopoda. Journal of Paleontology, 8(4), 422–432. http://www.jstor.org/stable/1298131
 

https://www.jstor.org/stable/1298131?read-now=1&refreqid=excelsior%3Aca1f206ddc8295fbdb79e611f8666add&seq=13#page_scan_tab_contents

 

 

02E2E3AB-F68F-4D24-842A-95BE9450BC9F.jpeg

141C5277-9EB3-4171-9AD7-2C69A22B9136.jpeg

 

 

I'm a little confused. image.png.98bede87a661e6764f608e916aec3372.png

 

Newell referred to it as Chonetes papilioniformis - is this just an archaic form of it?

~ Isaac; www.isaactfm.com 

 

"Don't move! He can't see us if we don't move!" - Alan Grant

 

Come to the spring that is The Fossil Forum, where the stream of warmth and knowledge never runs dry.

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And then he even refers to it as  image.png.be8c9f21e0e7487c389f30addfd02384.png

 

Very confusing...

~ Isaac; www.isaactfm.com 

 

"Don't move! He can't see us if we don't move!" - Alan Grant

 

Come to the spring that is The Fossil Forum, where the stream of warmth and knowledge never runs dry.

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2 minutes ago, IsaacTheFossilMan said:

And then he even refers to it as  image.png.be8c9f21e0e7487c389f30addfd02384.png

 

Very confusing...


I should have said Chonetina.

 

I think that there are several very similar generic names associated with this species; I have not figured out which one is most accepted.

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My goal is to leave no stone or fossil unturned.   

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I found the divergence of the walls of the fold to be around 47deg:

image.png.652532ebae59557292138c08aecddc6e.png

 

image.thumb.png.b5c2206057fce804966f7b187608eb49.png

Given 1.00 is 5mm, the average spacing of the radial lirae is (5 * 0.4775)mm, or 2.3875mm. 

This is a discarded measurement not to be used - see below post

 

image.thumb.png.b5a1af9d298da5506c99418e1193d77e.png

Given 0.50 is 5mm, thus 1.00 is 10mm, then the length of the specimen is 7.8mm, and the width is 10mm.

Length to width ratio = 1 : 1.282

 

Edited by IsaacTheFossilMan

~ Isaac; www.isaactfm.com 

 

"Don't move! He can't see us if we don't move!" - Alan Grant

 

Come to the spring that is The Fossil Forum, where the stream of warmth and knowledge never runs dry.

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Just now, DPS Ammonite said:


I should have said Chonetina.

 

I think that there are several very similar generic names associated with this species; I have not figured out which one is most accepted.

Neither, I've been looking all over.

~ Isaac; www.isaactfm.com 

 

"Don't move! He can't see us if we don't move!" - Alan Grant

 

Come to the spring that is The Fossil Forum, where the stream of warmth and knowledge never runs dry.

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Just now, IsaacTheFossilMan said:

image.thumb.png.b5c2206057fce804966f7b187608eb49.png

Given 1.00 is 5mm, the average spacing of the radial lirae is (5 * 0.4775)mm, or 2.3875mm. 

 

I've decided I can't see the specimen well enough to define the radial lirae, so ignore this measurement. i would need to see under a microscope.

~ Isaac; www.isaactfm.com 

 

"Don't move! He can't see us if we don't move!" - Alan Grant

 

Come to the spring that is The Fossil Forum, where the stream of warmth and knowledge never runs dry.

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Finding my diagnoses from The Superfamily Chonetoidea : catalogue of genera and species - Persée (persee.fr)

 

 

 

Looking at the diagnosis of Newell, N. D. (1934):

C. papilioniformis: 

  • the expected divergence of the walls from the beak is 34deg
  • length ~5.6mm
  • width ~9.5mm
  • L:W "in mature specimen does not range far from" 1 : 1.6

 

Looking at the diagnosis of Dunbar, C.O., Condra, G.E. (1932):

C. flemingi: 

  • the expected divergence of the walls from the beak is 25-30deg
  • length (calculated from ratio) ~8.4mm
  • width ~14mm
  • L:W "varying but more often less than" 1 : 1.7

 

The proportions of this specimen seem to not fit either of these - the divergence is waaay too high, and the l:w way too low. 

~ Isaac; www.isaactfm.com 

 

"Don't move! He can't see us if we don't move!" - Alan Grant

 

Come to the spring that is The Fossil Forum, where the stream of warmth and knowledge never runs dry.

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I'll try looking at other Chonetoidea (with distinct preference for the aforementioned genera).

 

 

~ Isaac; www.isaactfm.com 

 

"Don't move! He can't see us if we don't move!" - Alan Grant

 

Come to the spring that is The Fossil Forum, where the stream of warmth and knowledge never runs dry.

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Looking at the diagnosis of Dunbar, C.O., Condra, G.E. (1932):

C. flemingi var. alata: 

  • the expected divergence of the walls from the beak is 60deg (this is stated as "below the hinge-line")
  • length ~11mm
  • width ~22mm
  • L:W 1 : 2

 

Looking at the diagnosis of Dunbar, C.O., Condra, G.E. (1932):

C. flemingi var. plebeia: 

  • described as a smaller variant of C. flemingi, it is described as having sometimes rounded cardinal extremities 
  • length ~7mm
  • width ~12mm
  • L:W 1 : 1.714

 

Looking at the diagnosis of Dunbar, C.O., Condra, G.E. (1932):

C. flemingi var. crassiradiata: 

  • less strongly bilobed as other C. flemingi variants
  • length ~8mm
  • width ~15mm
  • L:W 1 : 1.875

 

Before I go further, it is worth noting that most of these species and subspecies are diagnosed with their rib count (which @minnbuckeye is going to have the unfortunate job of counting), density of radial lirae (note "crassiradiata" means "dense radii") and cardinal spine count. Without a magnifier, it is unlikely that we will be able to get a more precise ID. :shrug::SadSmile:

~ Isaac; www.isaactfm.com 

 

"Don't move! He can't see us if we don't move!" - Alan Grant

 

Come to the spring that is The Fossil Forum, where the stream of warmth and knowledge never runs dry.

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After your input, I now know why I couldn't ID. Never realized such measurements were needed. Your time is appreciated!!!

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1 minute ago, minnbuckeye said:

After your input, I now know why I couldn't ID. Never realized such measurements were needed. Your time is appreciated!!!

 

No worries! I have a feeling we both learnt the same amount from this - I've never really fully immersed myself in brachiopod ID until today!

~ Isaac; www.isaactfm.com 

 

"Don't move! He can't see us if we don't move!" - Alan Grant

 

Come to the spring that is The Fossil Forum, where the stream of warmth and knowledge never runs dry.

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