Pennsylvanian Fish of Illinois

[Tidgy's Dad]

This really is a great thread. 

Wonderful specimens. 

[connorp]

Thanks for the kind words all.

 

Here are a couple new finds. First some Petrodus denticles. For some reason they are all coming out as impressions. Even when I find them by splitting open a fresh layer of shale, the actual denticle isn't even there, just the impression. Kind of weird, but regardless I'm happy to finally find some of my own.

 

There is quite a range of shapes with these, ranging from very elongate to perfectly circular.

 

And although I have quite a few, I am again happy to finally find my own Listracanthus denticles. I've found quite a few so far plus many many partials, this is my favorite. The iron oxide(?) staining is quite visually appealing.

 

[connorp]

If you look at the Listracanthus specimen immediately above, you might notice some large bumps. Those are the result of phosphatic nodules, which are very concentrated in the lower Mecca Quarry Shale (equivalent). The fossils in these nodules top even those found in the Mazon Creek nodules. A high bar you say? Well by top, I do literally mean top, since this black shale immediately overlies the Francis Creek Shale where the MC nodules originate.

 

A lot of these are probably fish coprolites, so often what's inside is clearly a fossil but too jumbled and/or distorted to identify. These also do not split very well. Sometimes they split when you pull apart two sheets of shale (this is ideal), but if they don't I just hammer them and hope for the best. A lot of the fossils inside are very fragile or 3D and would probably shatter if freeze-thawed like MC nodules. They remind me a lot of the Muncie Creek nodules I've seen posted here, but these ones are usually very small. Most are about 1cm at the widest dimension.

 

I've split a couple hundred so far, here are my favorite fishy finds.

 

Palaeoniscoid scale

 

Partial Listracanthus denticles

 

A quite nice Petrodus denticle

[connorp]

I initially thought these were patches of fish scales, but have since learned that they are actually bits of the carpace of the flea shrimp Concavicaris sinuata. They are by far the most common identifiable fossil in these concretions.

 

And although not a fish, I do want to share this small guy. Easily my favorite find so far. I think it's a ammonoid, confirmation would be appreciated.

Part

Counterpart

[minnbuckeye]

Any evidence to a siphuncle being present?? 

 

Mike

[Al Dente]

7 hours ago, minnbuckeye said:

Any evidence to a siphuncle being present?? 

 

Mike

I’m pretty sure there is a siphuncle. I’ve circled it in red. Interesting preservation on this ammonoid.

 

 

[deutscheben]

Outstanding additions! That last Petrodus is especially nice, I am still hoping to turn one of those up in my hunts.

[connorp]

A vertebrate, not a vertebrate, a vertebrate, not a vertebrate... At least one study suggested the Tully Monster is closely related to lampreys, so I think that's enough to qualify it for this thread. I was aiming for my first Tully to be a personal find, but I came across a dirt cheap specimen that had potential to have the proboscis and claw preserved, and I couldn't pass it up.

 

A few more freeze-thaw cycles and a bit of prep work later:

This specimen preserves the anterior of the body with both the proboscis and claw. The body split weirdly, so the eye bar is buried but one eye is visible.

 

 

[bigred97]

Awesome! I wonder if there is any way to uncover the eye bar. I suppose you could keep freeze-thawing that piece. You would risk damage to the eye on that side, I suppose.

[connorp]

Finally able to add an Illinois classic to the collection.

 

Edestus heinrichi

Anna Shale Member

Carbondale Formation (Desmoinesian)

Herrin, IL

 

The crown is a bit beat up, but the tooth is much more detailed than the whorl I posted a while back. Still waiting to find one out in the field, but this more than suffices for now.

[connorp]

Here's a strange find I made yesterday in the LaSalle limestone.  It's maybe half a centimeter at the widest dimension. It's very reflective, so I didn't even notice the punctate surface until I put it under the scope. Looks too thin to be a tooth fragment, but I have no idea really

[Bullsnake]

20 hours ago, connorp said:

Here's a strange find I made yesterday in the LaSalle limestone.  It's maybe half a centimeter at the widest dimension. It's very reflective, so I didn't even notice the punctate surface until I put it under the scope. Looks too thin to be a tooth fragment, but I have no idea really

    

Maybe ostracod?

[jdp]

Fish scale. Strange one. This could be something like Pappophiscus?

[deutscheben]

The shape, texture and color sure looks like vertebrate although I’ve never seen anything exactly like that one before. Another interesting fossil from this site!

[connorp]

3 hours ago, jdp said:

Fish scale. Strange one. This could be something like Pappophiscus?

What kind of fish is that? I can't find any information on that genus.

[RCFossils]

I think this might be a partial Megalichthys scale.

They are relatively abundant in certain sections of the Bond Formation.

[jdp]

On 10/10/2020 at 3:34 PM, connorp said:

What kind of fish is that? I can't find any information on that genus.

It's a weird little ray-finned fish from the Bear Gulch, and I misspelled the name because it is a tongue-teaser and my offhand memory for name spelling can be shoddy...the genus name is Paphosiscus. It came to mind because it is characterized by these sorts of pore-canal systems perforating the scales and cranial bones. It's definitely not the same genus (Paphosiscus is aquarium fish sized and doesn't exceed maybe 10 cm in length) but I figured I'd mention it. My first thought was megalichthyid but the punctae/pores aren't really consistent with that ID.

[connorp]

My first non-shark tooth from the LaSalle Limestone. I would guess palaeoniscoid. It's tiny, only a couple of millimeters long. You can't tell from the photo, but the exposed surface of tip is missing, so I can't whether the tell-tale acrodin cap is present or not.

[Thomas.Dodson]

A very enjoyable thread with beautiful specimens. I had the fortune of getting into some Pennsylvanian fish fossils of Illinois while I lived there this summer so this thread interests me a lot.

[connorp]

5 hours ago, Thomas.Dodson said:

A very enjoyable thread with beautiful specimens. I had the fortune of getting into some Pennsylvanian fish fossils of Illinois while I lived there this summer so this thread interests me a lot.

Feel free to post your finds here, I'd love to see them!

[Huntonia]

Wow, I haven't really looked through this thread before somehow. Great finds! You're edestus whorl from earlier is especially impressive in my opinion. I can't wait to see more 

[Thomas.Dodson]

15 hours ago, connorp said:

Feel free to post your finds here, I'd love to see them!

I found this Peripristis semicirculatus in a shale outcrop in Vermillion County. Shelburn-Patoka Formations Undivided (what they used to call the Modesto Formation).

[Thomas.Dodson]

And this worn Petalodont crown (Chomatodus?) came from Union County. I believe the outcrop is Golconda Formation.

[connorp]

Found a small bag of LaSalle Limestone micros while organizing today. Always fun to rediscover fossils!

 

Looks like a chip of the cutting edge of a petalodont tooth

 

I find small pieces of cancellous bone often. Never anything more than little unidentifiable bits though, and very fragile.

 

A tiny scale, I'm guessing palaeoniscoid based on the rhomboidal shape.

[connorp]

Here's a cool little denticle. It feels familiar, maybe acanthodian? I will have to go back through my literature when I have time.

 

And then this super small thing. It superficially resembles a vertebra (to me at least), but I don't know.