Chondrichthyan spines from Utica, Illinois

[Joseph Fossil]

On Saturday I went fossil hunting with @Tales From the Shale in Utica, LaSalle County, Illinois! We drove for some time looking for roadcuts when we discovered an abandoned clay pit not too far away from the town itself. I learned later its rocks date to the Pennsylvanian period of the Carboniferous era. There were also a bunch of nodules there too, but mostly it was stark shale and Excello shale. We opened the shale rocks up and we found a massive amount of small fossil imprints. But we also found some likely Chondrichthyan spines which I was wondering if anyone could ID the genera?

 

This first specimen I found after breaking open a large piece of Stark Shale. I asked @Tales From the Shale for an ID and he said it very likely a Listracanthus spine.

 

 

 

 

Here is the specimen under a dissecting scope!!! The striations typically seen on chondrichthyans like Listracanthus or Cladodus are more visible here, but I'm a bit unsure if these could be matched to either of these genera?

 

 

 

 

 

[Joseph Fossil]

Later I opened up some of the large clay shale pieces I collected and I found these large black streaks, which are harder than the clay shale around them and have striations. I think these are Listracanthus spines or that of a large ctenacanthiform but I'm not 100% sure on the ID of genera? Would anyone be able to ID these specimens?

 

 

 

 

 

 

 

 

 

 

 

 

[deutscheben]

I don't see anything in the pictures of the first specimen that make me think it is a fossil. I would be inclined to think it is mineral deposits of some sort. 

 

The second specimens are definitely not fish material, but they could be fragmentary plant remains. They could also be mineral in nature though, it is hard to tell.  

[Fossildude19]

I agree - not really seeing any spines here.

Listracanthus spines are pretty distinctive looking.

Not seeing any of those features here.  

 

 

Image from this PDF.

[Joseph Fossil]

6 hours ago, deutscheben said:

I don't see anything in the pictures of the first specimen that make me think it is a fossil. I would be inclined to think it is mineral deposits of some sort. 

 

The second specimens are definitely not fish material, but they could be fragmentary plant remains. They could also be mineral in nature though, it is hard to tell.  

 @Fossildude19 @deutscheben I appreciate the imput, but I actually emailed the images of the first specimen after posting this topic to an ichthyology professor I know at the University of Chicago who also specializes in fossil fish. Though it was not in the very best preservation, he did ID the specimen positively as a Listracanthus spine.

[Joseph Fossil]

@Fossildude19 @deutscheben I also looked at the other specimens under a dissecting and microscope today and some do look like Listracanthus and Cladodus spines and denticles. One might be a cladodont or part of a crusher plate tooth.

 

 

 

 

 

 

 

[westcoast]

Can ypu get a clearer image of the 'feathery' denticles that are typical of Listracanthus?

[Joseph Fossil]

5 minutes ago, westcoast said:

Can ypu get a clearer image of the 'feathery' denticles that are typical of Listracanthus?

 

@westcoast I'll definitely try and I appreciate the suggestion! The one from the green Stark shale is incredible fragile - I got it under a dissecting scope but the matrix couldn’t fit under a microscope without me breaking parts of the matrix it's part of. I'm just a bit worried since it's shale one wrong hammer swing and the specimen might break in two or something. It's also just barley preserved so I wouldn’t be surprised if the feathery denticles I want to donate that specimen so I want to keep it as safe as possible. I did get some good photos of one of the smaller specimens under a microscope. 

 

 

 

The striations on a Listracanthus spine look pretty prevalent here!

[Joseph Fossil]

@Fossildude19 @deutscheben I am curious how common is stark shale in Illinois and how often can you find fossils in it?