Fossil in reddish sandy stone

[EphemeralMoose]

I've been chipping away at this cobble when I have spare time, and slowly exposing this fossil.

I found the stone itself in western Illinois, relatively near the rivers. The matrix is shockingly tough, I can only rarely make a difference with any sort of precision, unpowered hand tool. Each grain of sand is firmly in place and does not want to leave.

 

The exposed matrix was originally reddish to brownish, though newly exposed faces of chips broken off lack the red-brown color (the reddish color is entirely lost in the photos). Presumably the stone is Mississippian or Devonian. Other fossils in this rock are all flakey white brachiopod material ranging from 0.5 cm to 4 cm across at the widest points. I have tested some matrix scraps against vinegar, which dissolved the stone around the sand grains, but left the sand grains untouched.

I've decided to hold off on any more matrix removal until I know what I should expect to find in the matrix. I found a second one of these, but it chipped off and lost it in my prep area outside.

When it comes to the horses & zebras adage I always put more consideration into the zebras than I should, which is why I'm hoping this is some part of a vertebrate but more likely an oddly colored crinoid bit. We just don't have much vertebrate material where I'm at.

The photos with circular borders are taken through a stereoscope at 15x magnification. The others have some level of digital zoom applied, but have a scale nearby (mm, cm). I apologize for any focus issues, this new phone has a finicky camera.

 

[Kane]

It does look like a tooth. I would leave it alone until some of our other members can weigh in on this.

 

Placoderm tooth is my guess.

 

Compare with this example: 

 

[connorp]

Definitely a fish tooth. If Devonian, then from a ptyctodont placoderm. If Mississippian, then from a holocephalan. Could you post pictures of the whole rock and associated fossils? Also a more precise location (closest city is fine). Might help narrow down the age.

[EphemeralMoose]

18 minutes ago, Kane said:

It does look like a tooth. I would leave it alone until some of our other members can weigh in on this.

 

Placoderm tooth is my guess.

 

Compare with this example: 

 

That example is remarkably similar. If not a very different tooth of the same species (age and/or location) then certainly a different species. The one in the example you provided appears to have a more uniform texture than mine, but that also could be an optical trick due to mine still being quite dirty.

[EphemeralMoose]

1 minute ago, connorp said:

Definitely a fish tooth. If Devonian, then from a ptyctodont placoderm. If Mississippian, then from a holocephalan. Could you post pictures of the whole rock and associated fossils? Also a more precise location (closest city is fine). Might help narrow down the age.

In Illinois, across from St. Louis is as precise as I can be in a public post due to verbal agreement with the landowner. The landowner had problems with people trespassing before. I can provide photos of the rest of the rock shortly.

 

I can say that within an hour's drive if the area I found this, a geological survey found an arthrodire fragment in a Devonian matrix which was described as brownish-oxidized quartz-sand limestone with brachiopod and gastropod fossils.

[Fossildude19]

4 minutes ago, EphemeralMoose said:

In Illinois, across from St. Louis is as precise as I can be in a public post due to verbal agreement with the landowner. The landowner had problems with people trespassing before. I can provide photos of the rest of the rock shortly.

 

I can say that within an hour's drive if the area I found this, a geological survey found an arthrodire fragment in a Devonian matrix which was described as brownish-oxidized quartz-sand limestone with brachiopod and gastropod fossils.

 

 

County should be close enough.

[EphemeralMoose]

The beautiful red/brown oxide color really comes out in some of these photos.

 

[EphemeralMoose]

16 minutes ago, Fossildude19 said:

 

 

County should be close enough.

I would love to say exactly where I found it for both the joy of finding fossils and for scientific completeness. However, my current agreement with the landowner was all I could get. I knew I couldn't ID things found on the property by myself, so the landowner finally, begrudgingly said I could give the info stated. When I say they had trespasser issues in the past, it's an understatement. Their land is still recovering well over a decade later.

 

I hope I can show them this post after a few days and convince them to allow more information.

It was either zipped lips from me, or no fossils from that land for anyone. I am hoping this pushes them to be a bit more open.

 

I did forget I can share slightly more detailed info in PM's. It's the whole public access thing that bothers them.

Edited January 15 by EphemeralMoose
forget to add info

[Kane]

You certainly don’t want to break any confidences in public, so there may be other ways to figure this out. 
 

With the aid of a USGS bedrock map of the area, you should be able to cross reference this with the landowner’s location. Note the name of the formation. You can then research further to find out more about the formation by reading its lithologic description (reddish sandstone/grainstone would likely mean you have a match). 
 

Additionally, you have some other fossils in related sediments that might serve as index fossils. Some poking around the literature on brachiopods listed in that area may help pinpoint this further.

 

Once age and formation are known, then a deep dive into the literature for any listed fish/placoderm species. 
 

In a way, this route of sleuthing and clue collecting is a lot more fun!

[connorp]

I'm gonna go with Mississippian. Those brachiopods look like productiids which are plentiful during that time. Plus to my understanding, the Devonian units in that area are quite thin. Maybe @pefty recognizes this matrix.

[Collector9658]

This rock looks much like Bushberg Sandstone. Your teeth look very similar to the Ptyctodont teeth I found last year in the St. Louis area. Check around online and research on the county you located these in. There are exposures of Bushberg Sandstone scattered throughout the area in Central and Eastern MO, as well as Western IL.

 

The top and underside both look pretty consistent with the Placoderm teeth I found. Here's a post with some of the teeth I found if you want to compare.

 

https://www.thefossilforum.com/topic/135129-chomatodus-mississippian-fish-teeth-id/

 

Edited January 15 by Collector9658

[EphemeralMoose]

I sent the landowners screenshots of this post. After seeing that I was keeping my word, that other users others here respected the agreement, and their own curiosity about it being a tooth, they relented to allow me to share info that was previously relegated to private messages & emails.

That being said, I still feel responsibility to say don't trespass to get rocks, if a landowner says no you need to respect that, and don't leave signs that you were on the land busting rocks apart. Offering trades and to take the landowners with you may help them agree.

 

It's in Jersey County, IL.  The most similar matrix description is from the USGS Grafton Quadrangle bedrock map description of Cedar Valley Limestone, which is the youngest Devonian rock in the area and best matches the matrix in my layman's opinion. The exception to that is @connorp noting the brachiopods appear to be productiid brachiopods. The Cedar Valley Limestone (and sandstone) is described to be full of Paraspirifer and Mucrospirifer brachiopods, platycerid gastropods, and rugose corals.

[EphemeralMoose]

11 hours ago, Kane said:

You certainly don’t want to break any confidences in public, so there may be other ways to figure this out. 
 

With the aid of a USGS bedrock map of the area, you should be able to cross reference this with the landowner’s location. Note the name of the formation. You can then research further to find out more about the formation by reading its lithologic description (reddish sandstone/grainstone would likely mean you have a match). 
 

Additionally, you have some other fossils in related sediments that might serve as index fossils. Some poking around the literature on brachiopods listed in that area may help pinpoint this further.

 

Once age and formation are known, then a deep dive into the literature for any listed fish/placoderm species. 
 

In a way, this route of sleuthing and clue collecting is a lot more fun!

As a biologist, I'm all too familiar with the fun yet frustrating task of hunting down primary literature of species descriptions and distributions (mostly insects and plants). I managed to record two new state records of species newly found in Illinois this way, both ground beetles (Carabidae).

I'm also painfully aware that vocabulary is a make-or-break aspect of finding the right papers.

Any tips on finding the right papers or terms? Paleontology is a different world of phylogeny and vocabulary that I know very little of. Anything would be helpful. I've already started at Wikipedia's references.

[pefty]

On 1/14/2024 at 9:01 PM, connorp said:

I'm gonna go with Mississippian. Those brachiopods look like productiids which are plentiful during that time. Plus to my understanding, the Devonian units in that area are quite thin. Maybe @pefty recognizes this matrix.

 

Thanks for the tag, Connor.

MATRIX
Unfortunately, I don't happen to recognize this particular matrix other than as a clear example of a hematite-cemented quartz sandstone, but I trust Collector9658's visual match with the Bushberg above. As for the Cedar Valley Group, I have seen it but only in the quad cities and in central Missouri; as I understand, the southwest Illinois version is quite different anyway. In any case I have never seen the sandy facies of the Cedar Valley Group and so can't say whether the photos above look anything like it. 

 

BRACHIOPODS

I really like productoid brachiopods, but I have to say none of the pictured brachiopods looks particularly indicative or particularly productoid to me. (Fwiw there are common productoids in Late Devonian time, which I believe the Cedar Valley Group does admittedly extend into.) That said, I am not trying to argue in favor of a Cedar Valley Group interpretation here. As the OP notes, the pictured brachiopods are clearly not the typical Cedar Valley Group brachiopods, which along with the absence of coral seems a red flag for a Cedar Valley Group ID for the rock. Typical Bushberg Sandstone, on the other hand, lacks a preserved fauna other than shark teeth, at least in Missouri, but these seem to the most common brachiopods when any are found (Moore, 1928) :

• Schuchertella? sp.
• Camarotoechia sp.
• Delthyris missouriensis Weller
• Syringothyris bushbergensis Weller
• Spirifer jeffersonensis Weller 

And I could buy Schuchertella? for many of the brachiopod photos above. More focused photos with multiple angles of the same brachiopod might help clarify.

 

OTHER EVIDENCE

The dentine texture does seem a dead match for Ptyctodus as several folks mentioned above. (I am not a fish person, but even to me the pattern seems quite distinctive visually.) To me, Occam's Razor makes this Ptyctodus ID the strongest evidence that the OP is likely in the Bushberg Sandstone, since the Bushberg is a well known source regionally (though admittedly not the only one) for plentiful Ptyctodus.

 

All that said, I'm honestly not sure why this thread even needs to ponder the question of age/formation; the Illinois State Geologic Survey has produced highly accurate, detailed quadrangle maps that should allow the OP to pinpoint the age by pinpointing the location, as Kane noted above. Failing that, a look at the limestone above this sandstone should make a very easy check on the sandstone age. The sandstone is basal in the Cedar Valley Group, right? So the limestone above it should be classic Cedar Valley Limestone with classic Devonian corals, Mucrospirifer, etc. On the other hand, the Bushberg Sandstone is succeeded by Mississippian limestones either of the Chouteau Group or by cherty Burlington Limestone. Either of these should be easily distinguishable from Cedar Valley Limestone.

 

 

[jdp]

Just here to agree with the ptychtodont ID. This isn't the same material as the placoderm-bearing rocks a bit further south but it looks quite interesting. If you find anything more complete, I'd be keen to see some pics!

[Velvetmaggot]

I have property in the vicinity. I think I have a lot of fossils in similar matrix. I call it “sticky”.  

[EphemeralMoose]

22 hours ago, pefty said:

 

Thanks for the tag, Connor.

MATRIX
Unfortunately, I don't happen to recognize this particular matrix other than as a clear example of a hematite-cemented quartz sandstone, but I trust Collector9658's visual match with the Bushberg above. As for the Cedar Valley Group, I have seen it but only in the quad cities and in central Missouri; as I understand, the southwest Illinois version is quite different anyway. In any case I have never seen the sandy facies of the Cedar Valley Group and so can't say whether the photos above look anything like it. 

 

BRACHIOPODS

I really like productoid brachiopods, but I have to say none of the pictured brachiopods looks particularly indicative or particularly productoid to me. (Fwiw there are common productoids in Late Devonian time, which I believe the Cedar Valley Group does admittedly extend into.) That said, I am not trying to argue in favor of a Cedar Valley Group interpretation here. As the OP notes, the pictured brachiopods are clearly not the typical Cedar Valley Group brachiopods, which along with the absence of coral seems a red flag for a Cedar Valley Group ID for the rock. Typical Bushberg Sandstone, on the other hand, lacks a preserved fauna other than shark teeth, at least in Missouri, but these seem to the most common brachiopods when any are found (Moore, 1928) :

• Schuchertella? sp.
• Camarotoechia sp.
• Delthyris missouriensis Weller
• Syringothyris bushbergensis Weller
• Spirifer jeffersonensis Weller 

And I could buy Schuchertella? for many of the brachiopod photos above. More focused photos with multiple angles of the same brachiopod might help clarify.

 

OTHER EVIDENCE

The dentine texture does seem a dead match for Ptyctodus as several folks mentioned above. (I am not a fish person, but even to me the pattern seems quite distinctive visually.) To me, Occam's Razor makes this Ptyctodus ID the strongest evidence that the OP is likely in the Bushberg Sandstone, since the Bushberg is a well known source regionally (though admittedly not the only one) for plentiful Ptyctodus.

 

All that said, I'm honestly not sure why this thread even needs to ponder the question of age/formation; the Illinois State Geologic Survey has produced highly accurate, detailed quadrangle maps that should allow the OP to pinpoint the age by pinpointing the location, as Kane noted above. Failing that, a look at the limestone above this sandstone should make a very easy check on the sandstone age. The sandstone is basal in the Cedar Valley Group, right? So the limestone above it should be classic Cedar Valley Limestone with classic Devonian corals, Mucrospirifer, etc. On the other hand, the Bushberg Sandstone is succeeded by Mississippian limestones either of the Chouteau Group or by cherty Burlington Limestone. Either of these should be easily distinguishable from Cedar Valley Limestone.

 

 

I greatly appreciate your detailed summary of evidence.

I knocked this cobble off of a large boulder on the property -- larger than I figure anyone with machinery in any decade would care to move. Following the information you provided, I talked to the landowner about the history of the property. Previously they had insisted that everything on the land had originated on the land. Except that isn't true. They spoke of an old, abandoned, hairbrained project on their land. Long story short, the geographical information I have provided here is nearly useless as this massive boulder I sourced the stone from may have been brought onto the property. Lesson learned for the umpteenth time: trust, but verify. I'll update this thread in upcoming months whether or not I find similar stone in situ on the property or nearby areas. Until I find new evidence, I am suspending any of my implication it may be Cedar Valley Limestone/sandstone (uppermost Devonian material found in the area), and am deferring to the expertise provided by those in this thread that the stone is Bushberg sandstone. While Bushberg Sandstone is not included in the Illinois State Geologic Survey Grafton Quadrangle Bedrock map, the source stone may have been brought to the site, so it could be any sandstone described as having quartz grains of sand and as tough material. Those grains do not come off easily.

 

I can get some much more detailed photos of the brachiopods. If there are any in the photos above that you particularly wish to see in detail, please indicate which ones. Otherwise I'll just choose 1 or 2 to focus on.

Overall, I think I'm going to resume preparation, much slower than before.

[EphemeralMoose]

11 minutes ago, Velvetmaggot said:

I have property in the vicinity. I think I have a lot of fossils in similar matrix. I call it “sticky”.  

Would you be willing to provide photos of the similar matrix you have for comparison?

[Velvetmaggot]

I’ll find some better pics that I’ve taken, but I grabbed my nearest example…I could build a mother-in-law house with all the rocks I’ve collected.