Pennsylvanian Fish of Illinois

[connorp]

Over the past year, I've become fascinated with the often bizarre fish and sharks of the Pennsylvanian. Fortunately, my home state of Illinois is a great place to hunt for such fossils. I've shared several of these in other posts before, but wanted to put everything together in one thread. Probably won't have much to post for a few months after this, but once summer rolls around, I should hopefully have plenty of new finds to share.

 

I would say there are three major settings in which you can find fish fossils in Illinois: Mazon Creek, black shales, and limestone. I have not had luck at Mazon Creek yet, but hopefully that will change. So I'll start out with the black shales.

 

These specimens, my first fish fossils, were collected in August 2019 from the Mecca Quarry Shale exposed at a clay quarry in Utica, IL. This shale directly overlies the Francis Creek Shale (i.e. Mazon Creek) at this location. The three specimens below are stomach ejecta from some kind of fish, and are composed mostly of partially digested fish scales.

 

In addition, I found this very nice pair of associated acanthodian fin spines. The top fin has an area showing damage, possibly due to predation.

[connorp]

Next are a few specimens from another black shale exposed in Grundy/Kankakee County, the Excello Shale. It is lighter and more fissile than the Mecca Quarry Shale I've explored, and all fossils I've acquired so far are pyritized. The first three are Listracanthus hystrix dermal denticles collected at Pit 14 in Kankakee County, which is located directly below the popular Pit 11 where many of us hunt for Mazon Creek nodules. Unfortunately the site has been closed for a while, I'm guessing bulldozed to build a neighborhood.

 

This one was from this year's Christmas Auction. It is the largest and best preserved denticle I've acquired from anywhere in the US.

 

This partial denticle was found on the backside of the above specimen after a quick run under water to wash off the dust.

 

And I have one more, not super well preserved though.

[Misha]

Nice finds!

I always love seeing vertebrate material from the Paleozoic.

[connorp]

The last black shale specimen for now is a favorite of mine, a single tooth whorl of the bizarre shark Edestus. These are not uncommon in coal mines in Southern Illinois and elsewhere, and are colloquially known as 'coal sharks' for this reason. However, you don't often see these outside coal mines. This was stated as coming from the MQS, but having it in hand it very likely came from the Excello Shale, probably Pit 14 as well. There is also a bit of plant material on the plate, though not well preserved.

 

[connorp]

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.

 

[Carboniferouspat]

Thanks  for posting all that, very interesting information that I was not aware of. And I live in Illinois.Great specimens.

[connorp]

Now we'll move on the holocephalians. These chondricthyans are survived today only by the chimeras, or rat fish. On a single day, I often find up to a dozen fragments of these crusher teeth, rarely are they close to complete. And even when nearly complete, they can be hard to identify. These are the nicer ones I've found.

 

This is a nearly complete tooth plate, I believe Deltodus.

 

 

I find this one cool as there appears to be some kind of damage to the tooth plate. Possibly Psammodus.

 

 

This is definitely the most interesting one in my opinion. The unique curvature matches up quite well with Deltoptychius acutus, although I'm not sure if this species has been reported before from Illinois.

 

[connorp]

Here's the last specimen I have for now. This is probably my favorite find due the the spectacular coloration and stippling. I believe this tooth can be assigned to Cymatodus oblongus. In the Illinois Geological Survey (v.7 I think), it is stated that this species was erected for a single similar shaped tooth found in what is likely the same limestone. I can find no other examples of similar teeth published since then.

 

Thanks for looking! Hope this was interesting, and hopefully I'll have more to share in the coming months.

[Petalodus12]

These are some great finds! I’ve found my fair share of Carboniferous vertebrate fossils but my oceanic collection consists of a whopping 2 petalodus teeth. Thanks for sharing these with us!

[fossilsonwheels]

1 hour ago, connorp said:

Next are a few specimens from another black shale exposed in Grundy/Kankakee County, the Excello Shale. It is lighter and more fissile than the Mecca Quarry Shale I've explored, and all fossils I've acquired so far are pyritized. The first three are Listracanthus hystrix dermal denticles collected at Pit 14 in Kankakee County, which is located directly below the popular Pit 11 where many of us hunt for Mazon Creek nodules. Unfortunately the site has been closed for a while, I'm guessing bulldozed to build a neighborhood.

 

This one was from this year's Christmas Auction. It is the largest and best preserved denticle I've acquired from anywhere in the US.

 

This partial denticle was found on the backside of the above specimen after a quick run under water to wash off the dust.

 

And I have one more, not super well preserved though.

Fantastic finds !! These are some spectacular fossils. The Edestus and the Listracanthus are so cool. My Listracanthus is on really dark shale, very difficult to see. all of yours are really nice. Good luck with the future hunts.

[Tidgy's Dad]

Very interesting.

I love that associated acanthodian grouping. 

Than you for sharing your wonderful finds with us all.  

[deutscheben]

Thanks for gathering your excellent Pennsylvanian fish material together, @connorp. It's great to see some new material in there too- as an Illinois resident, Edestus has been on my dream list, but finding one in the field seems pretty difficult- I'm glad you could acquire a specimen! That Deltoptychius is also very cool and seems to be mostly complete. Here's to many more quality shark and fish finds for you!

[Misha]

That edestus tooth and jaw are very cool.

Not a shark though, closer relatives would be the holocephali you have

[connorp]

25 minutes ago, Misha said:

That edestus tooth and jaw are very cool.

Not a shark though, closer relatives would be the holocephali you have

I never even bothered to check that, interesting. All reconstructions look like sharks so I just assumed, but then again nothing besides the whorls are known. Shows just how little we know about these weird fish.

[deutscheben]

I highly recommend the book Resurrecting the shark by Susan Ewing http://pegasusbooks.com/books/resurrecting-the-shark-9781681773438-hardcover for an informative and entertaining look primarily at the Eugeneodontid Holocephalian Helicoprion, but also that order more broadly, including Edestus. It is written for a general audience, but still contains loads of scientific detail. 

[connorp]

I was reading a paper this morning about chondrichthyans from Arizona and a good point was made about Orodus. The teeth have been found in association with hyobodont material, and it’s very likely that teeth assigned to Orodus come from a variety of fish and are just a convergent form of teeth. So even though my tooth in particular is a good match for O. greggi, it would probably not be wise to assign it to that species. Since body fossils are known, the species is not just based on teeth, and thus it is not guaranteed the tooth comes from that specific shark despite being morphologically similar to its teeth.

[connorp]

I've recently been getting in microfossils, and found quite a few interesting fish specimens in the black shales. I've found the Excello to be much more rich than the MQS, although I have very few samples to search at the moment.

 

We'll first start with some conodont elements. No idea on the species, that will be a project for when I get a better microscope (I apologize in advance for the not spectacular pictures). As of right now, I'm just calling them either "straight" elements or "curvy" elements. Here are a few of the "straight" elements.

 

Here are some "curvy" ones.

 

This one is pretty fragmentary but is pyritized which is pretty neat.

 

 

Moving on, we have a few unknown things. Not sure what these are, I'm calling them scales for now although I have no real idea.

 

 

And finally, here is my favorite discovery. These are cladodont denticles. In the Indiana Excello, densely packed masses of these have been found sporadically. Rainer Zangerl proposed that some of these may not be teeth but actually dermal denticles, as the distribution suggests that the dense masses came from individuals, but sharks don't have enough teeth to account for the numbers found. However no such animal has been discovered, so this is just speculation.

 

[doushantuo]

Nice post,Connorp.

good visuals

kudos!

[doushantuo]

the straight conodont element looks "ozarkodinoid" (Idiognathodus?)to me,BTW but conodont taxonomy is plagued by a lot of methodological problems

The buccal apparatus of conodonts is a multi-element one,and a single element is rarely indicative of a genus.

 

[connorp]

Finally have a few new things to add. Here is a partial Deltoptychius armigerus tooth plate, a new species for me.

 

 

I think this next one is really pretty. Looks like a partial, but I couldn't find a match in any of my literature.

 

I also have one more new species, but I want to finish prep before posting.

[doushantuo]

Long shot:Menaspis armata

edit: will let it stand,Menaspis is primarily(solely?)known from the upper Permian

[deutscheben]

I missed your black shale micro post, very cool stuff!

 

The two most recent teeth are excellent as well, that last one is really lovely and quite intriguing. I have no idea what the ID would be, though. 

 

I have been slowly prepping one of the remaining pieces from my trip to the site last fall- I couldn't tell what it was at first, but it turned out to be a cladodont tooth preserved with the root facing out. I'm hoping that at least a few cusps are complete, but I'm not quite there yet. 

[connorp]

1 hour ago, deutscheben said:

I have been slowly prepping one of the remaining pieces from my trip to the site last fall- I couldn't tell what it was at first, but it turned out to be a cladodont tooth preserved with the root facing out. I'm hoping that at least a few cusps are complete, but I'm not quite there yet. 

Nice, the one I'm finishing prepping is a cladodont tooth too. It has all four outer cusps, and the median cusp is about 50% complete. Should be done in a day or two. I look forward to seeing yours.

[Tidgy's Dad]

I love the patterns on this sort of tooth plates.

Lovely. 

[connorp]

Here are two partial shark teeth from the LaSalle Limestone. On a given day I can usually find half a dozen partials, but the vast majority are very fragmentary and not worth the effort to prep out. These are two of the nicer ones I've found recently. The first is a Deltodus tooth plate. If complete it would have been pretty massive.

 

The second one is a tiny Orodus tooth that is nearly identical to the one I posted earlier. I have found quite a lot of probable Orodus partials, but this is the first I've found that included the central cusp. They are quite fragile and usually shatter during prep, luckily this one didn't.