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6/28 Illinois black shale trip w/ Listracanthus


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Last weekend I decided to take a short drive to Vermilion County, IL and get outside for a little bit. I haven’t been able to do any fossil hunting since COVID-19  reached our shores, so I had a few iffy sites less than 40 minutes from home in mind as I was driving. The first two proved fruitless, but I decided on a whim to take a new road over a local river in hopes of finding some exposures there. 
 

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The river was running high with verdant growth all around and dragon and damselflies filling the air. As I looked down from the bridge I saw sandy shore, concrete bridge abutment, and then a small section with some intriguing rocks scattered along the river’s edge.

 

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Once I made my way down to river level, I found that the black rocks visible above were pieces of black shale and coal. I was excited! I had been thinking of black shale since collecting some on an ESCONI trip last year and reading @connorp’s posts about black shale finds. This shale was much more fragile and bedded than the Mecca Quarry Shale I found last year, so I was able to split it easily by hand. I was too excited, so I forgot to take any in situ photos (I took the ones above on my way back to the car).
 

Before too long, I spotted the unmistakeable shape of a dermal spine from the iconic black shale chondrichthyan fauna Listracanthus hystrix- a strange shark relative covered in spiny denticles. 
 

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I spent about 30 minutes searching this small exposure and turned up several more Listracanthus, the inarticulate brachiopods Lingula and Orbiculoidea, fish scales, and some mysterious spine fossils. Unfortunately, almost everything was tiny (less than 1 cm) and I don’t have a macro lens for my phone yet, so photos of most of them will have to wait. Here is everything I kept after trimming the matrix down:

 

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I will share some more pics of the best Listracanthus in my next post.

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The Listracanthus denticles that I split were preserved with part and counterparts. This is the best one, it is complete with clear details.

 

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As I mentioned above, all of the fossils I found were quite small, both the fish and brachiopod remains. The Listracanthus I found were considerably smaller than the grouping I found in the Mecca Quarry Shale- here is a comparison:

 

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Finally, on the topic of tiny things, when examining the finds under a microscope at home I found many loose conodont elements, my first ones! But obviously there is no chance of me photographing them with my current set-up. 

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Always nice to find a new location. :)

Nice finds, would love to see the brachs in close up. 

One day....................

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Life's Good!

Tortoise Friend.

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Good sleuthing. Looking forward to seeing close up shots of conodonts. Sometimes I put my phone right up to the microscope lense and am able to get a decent shot.

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1 hour ago, aek said:

Good sleuthing. Looking forward to seeing close up shots of conodonts. Sometimes I put my phone right up to the microscope lense and am able to get a decent shot.

I have done this too. If you crop it a bit, the photos can come out quite nicely, although the resolution can sometimes be a problem.

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It is better to keep your mouth closed and let people think you are a fool than to open it and remove all doubt

 

-Mark Twain

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Thanks, @Tidgy's Dad, @aek, @Nimravis, @Monica, and @Thecosmilia Trichitoma! It really was a pleasant surprise, and I hope to do a lot more exploring in the area in the future.

 

I tried taking a few pics of some smaller ones through my loupe since I wasn’t having much luck doing it through the microscope, they are still a bit blurry though. 

 

First is an Orbiculoidea:


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Next is another inarticulate brachiopod, Lingula:

 

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And finally, what I think is a pyritized fish scale:

 

B82ABD25-B80C-4389-AF79-689EEE3D3DCD.thumb.jpeg.3b32a8345a63edc3bd3e810e722df0bb.jpeg 
 

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Thanks for the brachiopod piccies. 

Yum, yum. :)

Life's Good!

Tortoise Friend.

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3 minutes ago, aek said:

Nice assortment. I think #3 is a paleoniscoid scale.

Yup I agree. The rhomboidal shape is a good indicator.

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nice finds

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"Absence of evidence is not evidence of absence"_ Carl Sagen

No trees were killed in this posting......however, many innocent electrons were diverted from where they originally intended to go.

" I think, therefore I collect fossils." _ Me

"When you have eliminated the impossible, whatever remains, however improbable, must be the truth."__S. Holmes

"can't we all just get along?" Jack Nicholson from Mars Attacks

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Thanks all! I realized I forgot to mention the geological setting in my post- I believe, based on some nearby sites mentioned in field trip guidebooks, that this is an unnamed black shale member of the late Pennsylvanian Bond Formation.

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Cool trip report, and that listracanthus is awesome! You and Connorp have inspired me to do a Missouri shale post...just gotta make the time!

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30 minutes ago, Titan said:

Cool trip report, and that listracanthus is awesome! You and Connorp have inspired me to do a Missouri shale post...just gotta make the time!

Thanks, and I can’t wait to see your post, your entry for the FOTM contest was a stunner!

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I was finally able to take more macro shots of some of my finds through a loupe this evening. 
 

Up first, I was able to capture a few of the many conodont elements, they are not the clearest pictures- each was about 2 mm long:

 

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The rest of these finds are, I believe, various fish bits of some sort or another- please share if you have any ideas about IDs! 
 

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This next piece is larger- about 6-7 mm, and seems to show some fibrous structure beneath the surface. 
 

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This next larger scale? looks different than the other ones I have found, with distinctive ridges.

 

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This finely detailed scale? has a very different shape.

 

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These two scrappy pieces have somewhat similar morphologies.

 

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And here are some distinctly spiny spines- very pointy and sharp looking. The two images are showing both sides of the piece of shale, and there were a few more scattered elsewhere on it too.

 

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I also wanted to share some more of the Listracanthus denticles I found. First is a small one with relatively simple “feathering”

 

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Next is the largest one I found at over 4 cm. It required a little light prep to remove some of the mineral deposits covering it.

 

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I was also able to take closer pics of some of the ones I already shared above.

 

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Just found this topic,

Super cool finds!

I have seen these black shales many times on the forum but they still always seem to surprise me with how beautiful the fossils found in them are.

Palaeozoic Fishes and Brachiopods are some of my favorite fossils in general.

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Intriguing and mysterious finds. The light cream colored conodont probably indicates 90℃ metamorphism according to the conodont alteration index. Here's a paper you might find interesting.

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15 hours ago, Misha said:

Just found this topic,

Super cool finds!

I have seen these black shales many times on the forum but they still always seem to surprise me with how beautiful the fossils found in them are.

Palaeozoic Fishes and Brachiopods are some of my favorite fossils in general.

Thanks! I am hoping that this is just the first of many explorations of the black shale in this area.

2 hours ago, aek said:

Intriguing and mysterious finds. The light cream colored conodont probably indicates 90℃ metamorphism according to the conodont alteration index. Here's a paper you might find interesting.

Thanks, I will have to check that out later- although I am generally familiar with conodonts, I have to admit I have not done any in-depth reading about them yet (the link you attached didn’t work for me, but I believe it was this paper: Assessing the paleoenvironmental significance of Middle-Late Pennsylvanian conodont apatite δ18O values in the Illinois Basin?)

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