Pennsylvanian Fish of Illinois

[connorp]

A couple weeks ago I posted an ID thread for this small bit of bone, which was tentatively ID'd as a small fragment of a fish spine.

 

It spent the time since then in a vinegar bath and just finally was freed from the limestone yesterday. The picture above is the "back side" of it. The front side is really interesting I think.

 

 

[Mark Kmiecik]

Not looking much like spine anymore.

[deutscheben]

 Holy cow! That is most definitely not what I though it would look like under there. That is most fascinating, it seems like some kind of tooth element? But I have not seen anything like it before. Congratulations on another fascinating find. 

[connorp]

8 hours ago, deutscheben said:

 Holy cow! That is most definitely not what I though it would look like under there. That is most fascinating, it seems like some kind of tooth element? But I have not seen anything like it before. Congratulations on another fascinating find. 

It is quite perplexing. I scanned all the literature I've collected so far and found nothing like it. For what it's worth, the base is similar in composition to that of the partial cladodont tooth I posted earlier. Maybe @jdp or @Archie have seen something like it.

[deutscheben]

Could you explain how you used the vinegar for prep? I tried using some to dissolve matrix from this site and didn't see much effect after a few weeks. 

[connorp]

5 minutes ago, deutscheben said:

Could you explain how you used the vinegar for prep? I tried using some to dissolve matrix from this site and didn't see much effect after a few weeks. 

It is very slow. For reference, the specimen above (which is small) took three successive 1-day vinegar baths to be freed from the matrix. I haven't bothered trying to break down matrix to search for fossils, it would take weeks if not months and a lot of vinegar. I only use it when I have a partially exposed specimen that looks too fragile to use my engraver on. But even then, I've had quite a few specimens (nothing too nice fortunately) crumble up because there were evidently hairline fractures that were being held together by limestone underneath.

[connorp]

I received this beautiful tooth in the mail yesterday from another member: a nearly perfect Petalodus lateral tooth from the Anna Shale (Middle Pennsylvanian) in Southern Illinois. This would have been collected several hundred feet underground in a coal mine, so certainly a place I will never be able to hunt. The horizon it was collected from is the same where most Edestus whorls and pyrite suns from Illinois are collected.

 

[jdp]

On 5/13/2020 at 2:35 PM, connorp said:

A couple weeks ago I posted an ID thread for this small bit of bone, which was tentatively ID'd as a small fragment of a fish spine.

 

It spent the time since then in a vinegar bath and just finally was freed from the limestone yesterday. The picture above is the "back side" of it. The front side is really interesting I think.

 

 

Could be a chunk of a head spine from some sort of holocephalan. That would be my first guess here.

[Archie]

Wow, that is such an awesome and diverse collection! I love the crusher teeth you find. My first guess on that mystery object would be a section of holocephalan spine as well, what a cool piece!

[connorp]

2 hours ago, Archie said:

Wow, that is such an awesome and diverse collection! I love the crusher teeth you find. My first guess on that mystery object would be a section of holocephalan spine as well, what a cool piece!

Thanks! And yes I agree, crusher teeth are some of my favorites. A few of the ones I’ve found match up really well with species that have only been reported from your hunting grounds in Scotland and the greater UK. Makes me wonder just how many of the hundreds of described species are actually valid. 

[Rob Russell]

On 1/12/2020 at 9:50 PM, connorp said:

I'll now switch gears and move on to the marine limestones. All these finds are from the LaSalle Limestone of the Bond Formation exposed in Oglesby, IL. This limestone is upper Pennsylvanian, so slightly younger than Mazon Creek which is mid-Pennsylvanian.

 

The first is a classic shark tooth and the first I ever found. It is a very tiny Orodus tooth, possibly O. greggi. By the way, if you're ever in Chicago, you have to check out the Field Museum, if nothing else than for the massive ~6ft O. greggi specimen they have. I believe it is one of the most complete Pennsylvanian sharks ever found.

 

 

Next, another classic Pennsylvanian shark. These are fragments of Petalodus crowns, probably P. ohioensis. I have not found any complete teeth yet, although these fragments are super common. I rarely bother with them any more though, as they're usually much smaller than the ones below and tend to shatter during prep.

 

Cladodont teeth look the most like modern shark teeth out of the Pennsylvanian sharks. Unfortunately, to date I have only found this root fragment with a single cusp. Finding a complete one is on my bucket list for this new year.

 

Remarkable finds, and a fabulous presentation of your material! 

I’m curious to know, if you know, whether or not the greggi at the FM was found in the Lasalle limestones? Or even the Bond Formation; more specifically?

[connorp]

6 hours ago, Rob Russell said:

Remarkable finds, and a fabulous presentation of your material! 

I’m curious to know, if you know, whether or not the greggi at the FM was found in the Lasalle limestones? Or even the Bond Formation; more specifically?

I wish it were possible to find a complete shark in the LaSalle Limestone! I believe the one at the Field Museum came from the Logan Quarry Shale, from one of the small quarries Rainer Zangerl dug in the late 1900’s in Indiana.

[Archie]

On 5/19/2020 at 5:34 PM, connorp said:

Thanks! And yes I agree, crusher teeth are some of my favorites. A few of the ones I’ve found match up really well with species that have only been reported from your hunting grounds in Scotland and the greater UK. Makes me wonder just how many of the hundreds of described species are actually valid. 

Its really interesting to see the similarity between the fauna's! Agreed a lot the taxonomy definitely needs revising. 

[connorp]

25 minutes ago, Archie said:

Its really interesting to see the similarity between the fauna's! Agreed a lot the taxonomy definitely needs revising. 

Yes for sure, especially since most literature is from the late 1800’s. I’ve mostly given up on identifying teeth to the species level since it is a fairly fruitless effort.

 

I read a paper the other day that attempted to reclassify the various species of Edestus. The authors, if I remember correctly, used morphometric analysis to bring the count down from 13 to 4. I suspect something similar would happen with a lot of holocephalian tooth genera.

[connorp]

I just collected this partial Petalodus crown yesterday. It's the most complete tooth I've found so far, though is far from complete. But it is certainly quite beautiful!

[Fossildude19]

Very Nice! 

Even partials of this species are very cool to me! 

[deutscheben]

Awesome!!! I love the dendritic pattern on that crown, I have seen it on other fossils there, but this one looks like leopard spots or something. 

 

I'm glad to hear you were able to get out to the site, I might not be able to make it up there until the fall. 

[connorp]

It appears the petalodont gods are smiling down upon me this week. I believe this is a (nearly perfectly bisected) Ctenoptychius apicalis crown in lingual view. It's not in super good shape but the cusplets are mostly there which is cool.

 

[connorp]

These two specimens are not from Illinois (though they are from the Midwest), but both groups of fish are well represented in Illinois, and I love these specimens, so I'll post them here anyways.

 

This is a fairly completely paleoniscid from the famous Linton site in Ohio.

 

Second is a partial acanthodian from the famous Hamilton Quarry lagerstätte in Kansas.

 

Acanthodes bridgei

Hamilton Quarry (Upper Pennsylvanian)

Greenwood County, Kansas

[Archie]

Brilliant finds with those two petalodonts and love the two fish   Totally agree about the Holocephalan tooth genera, theres so much overlap and variation in morphology such as Psephodus dentitions having Helodus type anterior teeth and also possibly a preservation and collecting bias on the larger posterior tooth plates and then still so few articulated specimens to sort it out!

[deutscheben]

Nice additions to your collection! That Ctenoptychius is very cool with those sharp points.

[connorp]

Still in love with the Petalodus crown. Here are a couple shots under magnification. The dendrites (?) are quite lovely.

 

Lingual side                                                                                                  Labial side

  

 

I was acid prepping a small crusher tooth and decided to look through some dissolved matrix since I had my (very cheap) digital microscope out to take the pictures above. As I stated before, vinegar takes a long time to break the limestone down, so I got maybe a pill-capsule full of residue from soaking a grapefruit-sized limestone chunk in vinegar for 24 hours. But contrary to what I expected, I did find quite a few interesting items.

 

1) Some kind of denticle/armor plate

 

2) Another denticle/armor plate?

 

3) Maybe a fish tooth?

 

4) Fish tooth?

 

5) Two tiny Petalodus crown fragments

 

6) This was tough to get an angle on, but maybe a tiny cladodont cusp or something similar

 

7) This is the most interesting find. The spongy structure makes me think of specimens I've seen on here that were supposedly skull elements of tetrapods. Thoughts?

[deutscheben]

That is fascinating, thank you for sharing your results. It's good to know that the matrix really does contain micro vertebrate material, I will have to try the vinegar treatment on a smaller piece and be more patient. 

 

I don't know enough to say what #7 is, but #4 really looks like a dermal denticle to me with that flattened base. 

[connorp]

52 minutes ago, deutscheben said:

but #4 really looks like a dermal denticle to me with that flattened base. 

That's a possibility. I was thinking maybe an actinopterygian tooth as it looks like there might be a clear acrodin tip which I believe is unique to the ray finned fish. I think what looks like the "base" is extra material clinging on. Hard to say though. I really need to get a better microscope.

[connorp]

I found this just a minute ago and about screamed in excitement. Easily my best conodont find so far.