Subopercle (or Subopercule) Bones -- Who From?

[jbstedman]

I turned up subopercle bones from bony fish on recent hunts in North Carolina. The generic ID isn't in question (I don't think). The North Carolina Fossil Club's field guide to Neogene Fossils of North Carolina is pretty clear on what these are.

I was hoping for some help on linking these to particular genus and species of bony fish. The field guide points to pufferfish.

Is pufferfish a pretty reasonable ID for each of these?

broken and repaired (sort of):

[Guest bmorefossil]

yes it is and to add the first one looks to be reworked

Sphoeroides hyperostosus

extinct puffer, suboperculum

[jbstedman]

yes it is and to add the first one looks to be reworked

Sphoeroides hyperostosus

extinct puffer, suboperculum

Thanks.

What do subopercle bones from other fish look like?

Reworked? I'm familiar with that term being applied to fossils that, through erosion or being redeposited, appear in younger layers/formations than they originated in. In the Green Mill Run, everything is all mixed together in the stream (Cretaceous on forward). So, that makes sense. I take it that it's the black color that suggests that it was reworked.

Just for the record, the Green Mill one seems to be denser and fully fossilized (fully mineralized?) -- the second is more fragile (pretty clear since I found it in two pieces).

[Harry Pristis]

Thanks.

What do subopercle bones from other fish look like?

Reworked? I'm familiar with that term being applied to fossils that, through erosion or being redeposited, appear in younger layers/formations than they originated in. In the Green Mill Run, everything is all mixed together in the stream (Cretaceous on forward). So, that makes sense. I take it that it's the black color that suggests that it was reworked.

Just for the record, the Green Mill one seems to be denser and fully fossilized (fully mineralized?) -- the second is more fragile (pretty clear since I found it in two pieces).

I just looked at a page of line drawings of suboperculars of nine other families of fish. None looks much like the Tetraodontidae (Cf. Sphoeroides sp.) subopercular bone illustrated in the NC guide. That's not to say that the guide has it wrong. I just can't confirm that ID from my own resources. (Intuitively, the bones you have seem too "lumpy" to be part of the gill cover; but, the Tetraodontidae includes some unusual fish!)

"Reworked" may be equivalent to "stream-polished" in bmorefossil's observation. Fossils from spring-fed Florida rivers are always better mineralized than similar bones found in a dry (or dryer) situation. The spring water that feeds those streams are saturated with SiO2.

[jbstedman]

I just looked at a page of line drawings of suboperculars of nine other families of fish. None looks much like the Tetraodontidae (Cf. Sphoeroides sp.) subopercular bone illustrated in the NC guide. That's not to say that the guide has it wrong. I just can't confirm that ID from my own resources. (Intuitively, the bones you have seem too "lumpy" to be part of the gill cover; but, the Tetraodontidae includes some unusual fish!)

"Reworked" may be equivalent to "stream-polished" in bmorefossil's observation. Fossils from spring-fed Florida rivers are always better mineralized than similar bones found in a dry (or dryer) situation. The spring water that feeds those streams are saturated with SiO2.

Thanks, Harry. Perhaps a mystery. I exhausted my web browsing skills and found very little to help confirm this ID. Typically, the images are drawings of the skull with the various gill plate bones identified. Hard to tell what the subopercular bones would look like in 3-D.

[Maryland Mike]

Hmm. On the Fossilguy's website he shows what he says are suboperculum and postcleithrum bones from the puffer fish from Lee Creek.

Yours look much more like the postcleithrum.

Link to Fossilguy's page

[Harry Pristis]

Hmm. On the Fossilguy's website he shows what he says are suboperculum and postcleithrum bones from the puffer fish from Lee Creek.

Yours look much more like the postcleithrum.

Link to Fossilguy's page

I think "fossilguy" probably has it right. I don't have the photocopied page of the fish paper that illustrates the postcleithrum, darn it! The subopercular bones that "fossilguy" illustrates are quite similar to those nine fish illustrated in the same paper -- sort of banana-shaped. Good job, Mike.

There may be a few here who don't know what a "postcleithrum" is . . . here's a diagram of the boney fish pectoral bones which, you may note, support the pectoral fin.

[jbstedman]

I think the original ID by bmorefossil is probably valid.

Maryland Mike's ID prompted me to search the web for postcleithrum and it came up with a link to volume III of the Smithsonian series on Lee Creek (Geology and Paleontology of the Lee Creek Mine, North Carolina, III).

Surprisingly (I guess you can never search thoroughly enough on the web), when I uploaded my version of that volume and searched for the term, I also found images of what the authors identify as suboperculum bones from puffer fish. They match what I found very closely. The image of the postcleithrum included there is different -- much more of a stretched oval with tapered ends (what fossilguy is labeling suboperculum).

Here's a link to the Smithsonian report in case you don't have it -- [click here for a low-res version of the report -- still a large pdf file]. Look at page 186. The suboperculum bones in the image are characterized as being to varying degrees hyperostosed (I guess thickening of the bone).

Possibly, fossilguy has his labels flipped?

[Maryland Mike]

Hmm, a real mystery. If Smithsonian's Lee Creek Publication is right then you've got it.

This one is hard to find much on the internet on.

Check out these two links to Fishbase.org

Fishbase Subopercle definition

Fishbase Postcleithrum definition

Sounds like we need the input of a fish biologist to figure out this one.

[Harry Pristis]

I think the original ID by bmorefossil is probably valid.

Maryland Mike's ID prompted me to search the web for postcleithrum and it came up with a link to volume III of the Smithsonian series on Lee Creek (Geology and Paleontology of the Lee Creek Mine, North Carolina, III).

Surprisingly (I guess you can never search thoroughly enough on the web), when I uploaded my version of that volume and searched for the term, I also found images of what the authors identify as suboperculum bones from puffer fish. They match what I found very closely. The image of the postcleithrum included there is different -- much more of a stretched oval with tapered ends (what fossilguy is labeling suboperculum).

Here's a link to the Smithsonian report in case you don't have it -- [click here for a low-res version of the report -- still a large pdf file]. Look at page 186. The suboperculum bones in the image are characterized as being to varying degrees hyperostosed (I guess thickening of the bone).

Possibly, fossilguy has his labels flipped?

I am feeling a bit uneasy here because I don't have anything but a few line drawings to call upon. I haven't been able to open Mike's links, either. This being the case, I'll limit my remarks to these:

Errors are made in prime source documents. Little, bitty errors get ignored because the cognoscenti know the correct information. Such errors get passed on in subsequent, derivative publications which rely on the prime source information. This happens in all fields and areas of knowledge. With this premise in mind, what prime source documents did Dick Chandler use in his 1994 North Carolina guide? Or what source did "fossilguy" use to identify these bones?

It kills me that the page with the postcleithra was inadvertantly left out of the photocopy of my fish paper! Here are the subopercula illustrated in that paper. This bone is located at the bottom-rear margin of the gill cover, a location that seems to call for a flat bone. But, then, pufferfish are strange creatures.

[jbstedman]

I am embarrassed for not having pursued the ID as extensively as I should, though I think the NC Fossil Club field guide probably has it right.

Here is a copy of the relevant image from the Smithsonian Lee Creek volume III (p. 186) -- not sure how clear it will be. I understand the problems Harry and others might have opening the whole volume, it's huge. This might work.

I also violated a cardinal rule for IDing shark AND fish material -- always check elasmo.com before going public. I just found a page on puffers by Jim Bourdon on elasmo.com [this is the link]. This page has several pictures of suboperculum bones that match mine. Apparently, opercular material from Sphoeroides is considered abundant at Lee Creek and much of it very swollen (hyperostotic). If you read the Bourdon piece, be careful -- the label for an image is below the image.

[Maryland Mike]

Good detective work. With Elasmo as a start you at least have a couple references to primary sources, if you can get access to them. Jim Bourdon seems to be pretty careful in his research. This one has been an interesting journey and I wouldn't put it past Harry to turn up some more good info. I never in my life thought I would be learning about fish skeletal anatomy. Now there are a couple more bits I may recognize if I ever see them.

[Harry Pristis]

Good detective work. With Elasmo as a start you at least have a couple references to primary sources, if you can get access to them. Jim Bourdon seems to be pretty careful in his research. This one has been an interesting journey and I wouldn't put it past Harry to turn up some more good info. I never in my life thought I would be learning about fish skeletal anatomy. Now there are a couple more bits I may recognize if I ever see them.

Good work, JB. This was interesting stuff. The Elasmo images are sooo much more useful than line-drawings in this case!