Cephalopod siphuncle preservation...a curiosity of the Hamilton group in Western New York

[Al Tahan]

My exploration/presentation of possible (I believe probable) siphuncle preservation in Michelinoceras that I found at smokes creek in Buffalo, New York. Enjoy!

 

In the Hamilton group found in western New York (Wanakah shale, Windom Shale) you can find 2 straight shell nautilods known as Spyroceras and Michelinoceras. Both can be found throughout the Hamilton group but there is one particular bed at the base of the Wanakah shale on top of the Ledyard shale that has a high representation of Michelinoceras. The “Mt Vernon Bed” (seen in photo) is a very hard and concretionary calcareous shale with abundant cephalopods, Gastropods and some extra fauna mixed in. You can find this bed at smokes creek and rush creek behind Penn-Dixie in Buffalo, New York

 

The scientist in me likes to collect type (exemplary) specimens...something represantive of the species I can refer to. Once I have a great specimen I’ll only collect other “type” (exemplary) quality specimens or rare “oddities”. I recently found some rare oddities stored away that I collected of Michelinoceras a few years ago. I decided to put some study time into them cause I never really looked at them hard. After some research and observation I think I know what I’m seeing and I’m going to share my thoughts but I would love to hear from some cephalopod experts! 

 

Pic 1 : stratigraphic setting 

 

 

Pic 2: type (exemplary) specimen typical of Mt Vernon bed.

 

 

Pic 3: 2 large supplementary type (exemplary) specimens I have. The complete specimen actually shows very faint sipluncle evidence at the bottom of the picture. 

 

 

 

Pic 4: Bombshell specimen that allowed me to link and ID  the specimen in picture 5 as a Michelinoceras. 

 

 

Pic 5: Partial Michelinoceras showing this same oddity seen in picture 3 and 4.

 

 

 

I am going to follow up with more up close pictures and a few words/ evidence on what I think it is.

 

 

 

 

 

[Al Tahan]

These photos show my “bombshell” specimen. When I collected this specimen I thought I found a Crinoid on top of a cephalopod.

I’m now seeing a much different story....more pictures to follow and the conclusion.

 

 

[Al Tahan]

These last set of photos show what I think are the best preserved siphuncle remains even though the full specimen is gone. These cephalopods made shells with aragonite and you only get casts and molds really. No actual shells. 

 

Siphuncle basics: soft tissue connecting the partitions together and used in bouyancy control....this is a soft part so it would not typically preserve.

 

Basic fossil oddity observations:

1. Appears cylindrical in shape and partitioned.

2. Black carbon-like film on the cylindrical shapes.... just like that found on fossilized organic remains like plant matter. 

3. Found only at the most narrow segments of the shell.

 

How do you preserve a soft structure inside a cephalopod? 

 

My thoughts:

 

1. Siphuncle needs to be structurally preserved somehow......if the shell is completely crushed this will compromise the internal structure and siphuncle. I usually see some type of crush evidence on the wider portions. I think some shells stay intact in the narrow portions because they will resist crushing more and preserve the inter structures and siphuncle. 

2. It needs to have been filled with sediment. You need a matrix. The soft tissue could not have become the hard little segments observed on the fossil. It has to have been filled with sediment leaving a cast of the siphuncle with a thin black carbon film of organic remains.

3. It needs to survive....these are pretty delicate and I have another specimen I can’t find right now with pits showing where the little siphuncle structures would have been but they were destroyed. 

 

I drew up a preservation scenario for these and I don’t know many other ways to pull this off. I think this wasn’t all too common because I never really saw this much...maybe a few times. I imagine all the factors have to come together just right. 

 

Preservation story:

 

1. Michelinoceras dies in possible storm deposition event (Mt Vernon bed believed to be such) and is filled with sediment...including siphuncle.

2. Some of the sediment filled siphuncle is not crushed at narrow end of shell and internal structure is preserved.

3. Shell dissolved away over millions of years and we are left with internal structures with carbon remains where the organic material of the siphuncle was. Partitions form between the siphuncle remains due to the septal neck on each partition of the shell. This makes it so there is a small organic tube connecting each partition separately and not one long continuous organic tube running through each partition. 

 

I hope this is acceptable to the cephalopod expert and fossil oddity enthusiasts. I really do think these can only be siphuncle fossil remains in the form of internal molds.

 

That’s all for me,

Al

[The Amateur Paleontologist]

I really like how you're drawing interpretations out of your fossil finds - you're approaching the situation with quite the scientific mind, I must say  Best part of this thread was probably your research notes on 'Siphuncle preservation scenarios'

Keep up the good work!

 

-Christian

[Fossildude19]

I removed the other topic, Al. One topic is fine. 

If you want something moved, just let one of the Admins or Mods know.   

 

I also fixed the Font and some formatting.

 

 

 

[FossilDAWG]

Interesting post, thanks!

 

I suspect the specimens with traces of the siphuncle and septa are partially pyritized, with the pyrite altering to some other mineral secondarily.  Pyrite deposition is known to be sometimes influenced by decaying organic/bacterial deposits.

 

I'd suggest you avoid the term "type" or "type specimen".  This term has a very specific meaning, as it refers to the holotype (the single specimen selected by the author of the species as the best representative, the one that she/he mostly based the description on) or a paratype (one of a set of specimens that were used as the basis of a species description).  Your specimens are not "types" (or if they are they belong in a museum), but they may well be "typical" or "exemplars" (especially well preserved examples of a species).  

 

Don

[Al Tahan]

5 hours ago, FossilDAWG said:

Interesting post, thanks!

 

I suspect the specimens with traces of the siphuncle and septa are partially pyritized, with the pyrite altering to some other mineral secondarily.  Pyrite deposition is known to be sometimes influenced by decaying organic/bacterial deposits.

 

I'd suggest you avoid the term "type" or "type specimen".  This term has a very specific meaning, as it refers to the holotype (the single specimen selected by the author of the species as the best representative, the one that she/he mostly based the description on) or a paratype (one of a set of specimens that were used as the basis of a species description).  Your specimens are not "types" (or if they are they belong in a museum), but they may well be "typical" or "exemplars" (especially well preserved examples of a species).  

 

Don

Thanks!!! I should have been more specific about the type specimen part. I just like to have a “personal” type specimen...just a personal thing that sounds nice in my head ha...but I should probably use different verbiage so I don’t step on the toes of hard working geologists. I appreciate the feedback....I like “exemplar” specimens best  

[Al Tahan]

5 hours ago, Fossildude19 said:

I removed the other topic, Al. One topic is fine. 

If you want something moved, just let one of the Admins or Mods know.   

 

I also fixed the Font and some formatting.

 

 

 

Omg thank you!! I’m still getting the hang of things here. I appreciate you stepping in and helping a newbie like me out  . Great to know I can reach out as well!

[Fossildude19]

Happy to help Al - anytime.  

[Al Tahan]

@The Amateur Paleontologist Thanks! The drawing was just me trying to share my vision haha and I like drawing science stuff lol. I didn’t want to just make a wild claim with a photo without actually giving a defense. It was fun trying to figure out and fun presenting it to the forum. I did a handful of geology presentations in school it and was nice to dip into that type of thinking again  . I have an unknown fossil I may post soon...I’m totally stumped. 

 

I didn’t think a whole lot about pyrite @FossilDAWG .  So you think maybe the black “film” I talked about is possibly microscopic pyrite as a result of the organic material? 

[ynot]

2 hours ago, Al Tahan said:

 So you think maybe the black “film” I talked about is possibly microscopic pyrite

Pyrite is a brass colored mineral, so black is not pyrite.

Maybe manganese or hematite.

 

Since @Fossildude19  deleted My reply, I reiterate-- nice!

[Fossildude19]

3 minutes ago, ynot said:

Pyrite is a brass colored mineral, so black is not pyrite.

Maybe manganese or hematite.

 

Since @Fossildude19  deleted My reply, I reiterate-- nice!

Sorry Tony.  I tried to move it, but it came at the top of this topic - it puts posts in order by time posted.

I didn't want to cause any confusion.  

[ynot]

1 minute ago, Fossildude19 said:

Sorry Tony.  I tried to move it, but it came at the top of this topic - it puts posts in order by time posted.

I didn't want to cause any confusion.  

Would have been the first time a reply came before a topic eh.

Oh well.

[Fossildude19]

Right. No cart before the horse.   

[Al Tahan]

@ynot I’ve been told that microscopic pyrite and even calcite can appear black if the crystals are small enough.......I never read this in anything scholarly and it was word of mouth so I never considered it a verified truth. I though maybe Don was referring to that but I don’t think I made the right connection lol. Perhaps he was referring to the pyrite in another sense 

[ynot]

Sometimes pyrite that has been altered to other minerals can  be black and is still (inaccurately) referred to as pyrite.

Calcite is a colorless mineral and any "color" it exhibits is from other mineral impurities in the crystal structure.

Size of the crystals does not make any difference.

[Al Tahan]

@ynot thanks!! Great information. This is why I joined this forum. Much appreciated 

[doushantuo]

Some of you may like this:

Palaeontology,v.61-2/2018

RAPID COMMUNICATION

EVIDENCE FOR PALAEOZOIC ORTHOCONIC

CEPHALOPODS WITH BIMINERALIC SHELLS

KENNETH DE BAETS and AXEL MUNNECKE

 

(about 9 MB)

some thoughts

the phanerozoic has known "aragonitic" and "calcitic" seas..

The amount and (depth) of carbonate saturation would presumably have an impact on the taphonomy and diagenesis of aragonitic molluscs

The narrow segment of the shell might have a different mechanical strength from the wider parts.

The last septum might have imploded at around 300 m depth

Given what the siphuncle does,it is not beyond the realms of possibility that the siphuncle was filled with liquid*

The conchiolin in the siphuncle might imply that that part of the animal was taphonomically different.

* on the seafloor,not in the water column

 

I have pointed to this PDF a couple of times :

 

evansphragmocoimplosprocestaphocephalopaleozoicvol35_part3_pp585-595.pdf