Phosphatic Concretions Of The Pennsylvanian Muncie Creek Shale

[Plantguy]

1. It's hard to say how many. We've gone through so many over the years. I'd say roughly a thousand concretions to find a Lawrenciella (though Roz may have had better luck in Texas). Even more are needed to find a complete shrimp.

2. We've always used a hammer. It starts with taps, then whacks, then smash. We hadn't tried freeze-thaw (actually, we hadn't thought of it, and early on, I'm not sure what my parents would have thought of a couple hundred nodules in the freezer. ). Hammering is rough, but I'm not sure how freeze-thaw would work on complexly structured fossils like Lawrenciella and ammonoids. I'm afraid they would fall to pieces. Still, it may be worthwhile to prep certain pieces like specimen #4 above by freeze-thawing away some of the nodule matrix.

3. There are most likely no Euproops or any other freshwater types. The preserved fossils in the Muncie seem to be pelagic animals that lived closer to the surface of the open sea and then sank to the anoxic bottom after death.

Thanks Missourian for taking the time to explain some of the process! I should probably go read something about the mid-continental Penn basin and what was going on geologically back then--appreciate the Muncie faunal insights! Regards, Chris

[Missourian]

So how do you tell bony fish from cartilaginous fish? It's fairly easy, but I didn't clue in until recently.

 

Bony fish elements in these concretions usually have the smooth to spongy texture like any bone that we'd see in everyday life (eg. steak bones left on the plate at Ponderosa). Examples:

 

 

 

Cartilaginous fish elements, on the other hand, typically have a fine cellular, almost honeycomb-like texture. Example:

 

 

 

This is just the first step in identifying a bewildering assortment of scattered skeletal elements....

[Roz]

I did not know that.. I now have a notebook just for fossil fish/sharks information and that is one page 1.

I have to start somewhere.. I am glad you posted that!

[Missourian]

Speaking of cartilaginous fish, here is a piece that resembles Lawrenciella at first glance:

 

 

Again, the honeycomb structure indicates that this is a piece of a shark:

 

[Missourian]

Through the microscope:

 

 

 

I don't know where this piece fits into the shark skeleton, but it does appear to be bilateral. Skull, perhaps?

[Roz]

I love those halves! I think it looks like something found in the skull but have no idea

of exactly what! I will be interested in what others think..

[Coco]

Hi,

Missourian, are you sure it is selachian ? I understand you mean it is selacian skin (had I well understand ?).

Shark and ray skin is covered with small very hard "scales", consisted of the same material as their teeth (dentin). These small scales seem relief. On your pics, I see "holes", and not relief.

Would it be the imprint of the small scales ?

Here are pics of recent shark skins :

Centrophorus squamosus

Centroscymnus coelolepis

Galeorhinus galeus

Mustelus asterias

Coco

[Missourian]

On 7/1/2013 at 3:58 AM, Coco said:

Hi,

Missourian, are you sure it is selachian ? I understand you mean it is selacian skin (had I well understand ?).

Shark and ray skin is covered with small very hard "scales", consisted of the same material as their teeth (dentin). These small scales seem relief. On your pics, I see "holes", and not relief.

Would it be the imprint of the small scales ?

Here are pics of recent shark skins :

 

Selachian.... I haven't even heard of that before, so I'm not sure.

 

If by 'selachian', you mean 'shark skin', then yes. I figure it's shark because of the cellular structure of the fin 'bones' below the covering, as well as the scales. I figure these are scales (dermal denticles) because of their regular pattern and the fact that they are preserved at all. The lighting is from above, if that helps in interpreting the photos. To my eyes, they appear to be little barbs that are nearly parallel to the surface. They could merely be the imprint of scales, especially considering they aren't differentiated like those in the photos you provided, but I would think some actual scales would still be in place.

[Coco]

Sharks, rays, skates and ratfishes are selachians, they are cartilaginous fishes.

Coco

[Missourian]

On 7/1/2013 at 2:53 PM, Coco said:

Sharks, rays, skates and ratfishes are selachians, they are cartilaginous fishes.

Coco

 

Ok.

 

Regarding cartilaginous versus bony, I was going primarily by the structure of the skeletal elements. For convenience, here are some in a (somewhat blurry) cropped portion of the image posted above:

 

[Missourian]

'Baby back rib' :

 

 

The 'bone' broke completely free from the concretion:

 

 

It is massive like the 'chicken bones' that occasionally show up in the concretions (see http://www.thefossilforum.com/index.php?/topic/25758-phosphatic-concretions-of-the-pennsylvanian-muncie-creek-shale/?p=412571 ), but they are not related:

 

 

Instead, this is a skeletal element of a shark. Under the microscope, the cellular structure of cartilage can be seen:

 

[Missourian]

Colorful fish scales....

 

 

 

[crinoid1]

Nice fossils! I especially like the fish mandible. Thanks for sharing!

Gabe

[Missourian]

On 7/3/2013 at 11:50 PM, crinoid1 said:

Nice fossils! I especially like the fish mandible. Thanks for sharing!

Gabe

 

Thanks. Since a number of people like the mandible, here is another:

 

 

Under the scope. This is a combination of two images:

 

[Missourian]

Teeth:

 

 

Surface detail. The pores may be vascular canals:

 

 

Bone structure:

 

[Missourian]

Many Muncie Creek concretion contain regurgitation and coprolites of fish. Besides revealing much of their diet, they conveniently 'bundle' together the remains of various species that can be readily studied. In some cases, this may be their only preservation.

 

Regurgitation (left) and coprolite:

 

 

At least a couple distinctive types of scales can be spotted in the throw-up:

 

 

The material in coprolites has been through more (no pun intended ):

 

 

It's hard to make out anything for certain. The chip-like things are probably the remains of scales.

[Plantguy]

Many Muncie Creek concretion contain regurgitation and coprolites of fish. Besides revealing much of their diet, they conveniently 'bundle' together the remains of various species that can be readily studied. In some cases, this may be their only preservation.

Regurgitation (left) and coprolite:

8254-Muncie-regurg-coprolite.jpg

At least a couple distinctive types of scales can be spotted in the throw-up:

8240-Muncie-regurg.jpg

The material in coprolites has been through more (no pun intended ):

8231-Muncie-coprolite.jpg

It's hard to make out anything for certain. The chip-like things are probably the remains of scales.

Well, Missourian, I am fascinated, particularly of the scales. My initial thoughts however brought back lots of fond memories of having young kids and having a dog and cat in the house and all of those unexpected gifts they provided us! Just kidding!

Keep those nodules coming! Wish I could bust a few open myself. Regards, Chris

[Auspex]

Name the left one "Ralph".

[Missourian]

On 7/5/2013 at 11:57 AM, Plantguy said:

Well, Missourian, I am fascinated, particularly of the scales. My initial thoughts however brought back lots of fond memories of having young kids and having a dog and cat in the house and all of those unexpected gifts they provided us! Just kidding!

 

No hairballs or carpet yarn in any of these concretions.

[crinoid1]

Those scales are awesome, and the shark bone is unreal. Amazing stuff, and the preservation looks astounding.

Gabe

[Roz]

Through the microscope:

7883-Muncie-shark-element-4.jpg

7877-Muncie-shark-element-3.jpg

I don't know where this piece fits into the shark skeleton, but it does appear to be bilateral. Skull, perhaps?

I think you may be right on skull.. I have looked numerous times and I can't think of anything else

that it could be with that shape.. Very cool!

[Missourian]

More fish regurgitation (reposted from my 'Adventures in Microscopy' thread)....

 

This one contains a jumble of fish bones, scales, plates, spines, and whatever else:

 

The detail is exquisite:

 

A close-up of a complex skeletal element of some kind:

[Missourian]

More....

 

A jumbled mess:

 

Stack of 'plates':

 

Close-up of some intriguing details:

[Roz]

More....

A jumbled mess:

2347-Muncie-4-coprolite-plate-pile.jpg

Stack of 'plates':

2368-Muncie-5-Coprolite-plate-stacks.jpg

Close-up of some intriguing details:

2372-Muncie-6-coprolite-plate-detail.jpg

Very nice plates! I love looking at these.. I have found a few so far.. That first one you posted is very large.

I am really curious about those white structures that are almost shaped like double sided jaws with teeth. I wonder

where on the fish they were! I haven't seen that before.. Hmmm

[Missourian]

On 7/10/2013 at 5:49 PM, Roz said:

I am really curious about those white structures that are almost shaped like double sided jaws with teeth. I wonder

where on the fish they were! I haven't seen that before.. Hmmm

 

The only thing I can think of is that they were some kind of reinforcing structures in the plates.