Unknown new Fossil Decorah Formation Ordovician

[Tetradium]

First trip of the year to Decorah Shale Formation in Ordovician Minnesota. This was one of the few fossils I found - I assumed it was a regular Large Gumdrop Bryozoan, Prasopora conoidea. Then when I got to cleaning the clay and soft shale off it looks so different. No noticeable pores and sharp angles.  Here's two Large Prasopora conoidea - one smooth form and one rough and layered form on the left side for comparation. There is also a little Hormotoma fragilis gastropod on top. It doesn't even look like a trace fossil, as trace fossils are usually harder than usual shale or gathering of coarse sediments. 

 

[Crusty_Crab]

If you'll allow me to recite one of my mantras regarding invertebrate specimens, my response is "If there is a question of identification, your first step is high magnification."  

 

You are not sure if your specimen is a bryozoan. Bryozoans are colonial organisms. That should be evident under magnification. I do not hold much to gross morphology when it comes to a colonial organism. 

 

Looking at my examples from the Decorah Shale of Minnesota, here are some examples under 25.8x magnification:

To the left is a part of a trilobite, to the right a bryozoan. 

 

To the left, a bryozoan and to the right a part of a trilobite cephalon.

 

Above is what I consider classic bryozoan morphology.

 

Round specimens are crinoids. You can see a partial example with radial spines pointing to the center. Next to it is a bryozoan with classic fenestrate type structure.

 

Here you see long striate ribs indicative of a brachiopod. The bryozoans have a fenestrate structure to the bottom.  

 

Anyway, thats a first pass analysis. There are always exceptions to the rule in science, but I'd like to see a good high magnification image to start. Perhaps some of the more experienced members with the Decorah Shale can offer a better perspective.

 

 

 

 

[Tetradium]

7 hours ago, Crusty_Crab said:

If you'll allow me to recite one of my mantras regarding invertebrate specimens, my response is "If there is a question of identification, your first step is high magnification."  

 

You are not sure if your specimen is a bryozoan. Bryozoans are colonial organisms. That should be evident under magnification. I do not hold much to gross morphology when it comes to a colonial organism. 

 

Looking at my examples from the Decorah Shale of Minnesota, here are some examples under 25.8x magnification:

To the left is a part of a trilobite, to the right a bryozoan. 

 

To the left, a bryozoan and to the right a part of a trilobite cephalon.

 

Above is what I consider classic bryozoan morphology.

 

Round specimens are crinoids. You can see a partial example with radial spines pointing to the center. Next to it is a bryozoan with classic fenestrate type structure.

 

Here you see long striate ribs indicative of a brachiopod. The bryozoans have a fenestrate structure to the bottom.  

 

Anyway, thats a first pass analysis. There are always exceptions to the rule in science, but I'd like to see a good high magnification image to start. Perhaps some of the more experienced members with the Decorah Shale can offer a better perspective.

 

Ok I can try that. It will take time for me to do it as I have been really busy, This weekend is no exceptions. I do knows some Bryozoans but its still very tricky to id. I am just showing why I thought it was Prasopora conoidea at first but the lack of pores killed it. Later I will have to look at my trace fossils as I am musing about whenever it is an isolated example of one. 

Your last picture looks like Phylloporina sublaxa. I don't find Phylloporina sublaxa that often and they are much more lace like compare to Stictoporellina cribrosa and I usually finds Phylloporina sublaxa in tiny pieces less than half a inch long. The others bryozoans in your pictures are what I had classified as "Homotrypa" types - I hadn't researched that far yet as most looks very similar. The ones I have classified as far is Batostoma fertile/Batostoma minnesotense. They are large pores types, which makes them distinct from most other bryozoan, and I still are researching some more but one unproved theory that I have is they start out as crusting on hard substances then develops into stubby rugosa forms. 

 

The others that I have is Stictoporellina cribrosa/Stictoporella frondifera, Hallopora multiabulata, even a few Nicholsonella sp. And that's just the named ones ha. I still have to pore over that one online documentary - I have one distinct rugosa type that is much longer than the others with pore structures similar to Stictoporella frondifera but is still searching to name it. The more distinct they are, the more I can whittle down the names and such. 

7 hours ago, Crusty_Crab said:

 

 

 

[Tetradium]

On 4/1/2022 at 1:26 PM, Crusty_Crab said:

If you'll allow me to recite one of my mantras regarding invertebrate specimens, my response is "If there is a question of identification, your first step is high magnification."  

 

You are not sure if your specimen is a bryozoan. Bryozoans are colonial organisms. That should be evident under magnification. I do not hold much to gross morphology when it comes to a colonial organism.

Finally found the link again. 

 

The Bryozoa of the Lower Silurian in Minnesota : Ulrich, Edward Oscar, 1857-1944 : Free Download, Borrow, and Streaming : Internet Archive

[Tetradium]

On 4/1/2022 at 1:26 PM, Crusty_Crab said:

If you'll allow me to recite one of my mantras regarding invertebrate specimens, my response is "If there is a question of identification, your first step is high magnification."  

 

You are not sure if your specimen is a bryozoan. Bryozoans are colonial organisms. That should be evident under magnification. I do not hold much to gross morphology when it comes to a colonial organism. 

 

Anyway, thats a first pass analysis. There are always exceptions to the rule in science, but I'd like to see a good high magnification image to start. Perhaps some of the more experienced members with the Decorah Shale can offer a better perspective.

 

Sorry but I have to add one more thing I just found out - omit the species. I'm sorry but I didn't realize there are several species into genus Phylloporina that is also found into Decorah Shale Formation. 

 

[Tetradium]

On 4/1/2022 at 1:26 PM, Crusty_Crab said:

If you'll allow me to recite one of my mantras regarding invertebrate specimens, my response is "If there is a question of identification, your first step is high magnification." 

No pores seen with a closeup picture. The second picture is a beautiful trace fossil from Decorah Shale that might resembles this this one.

 

Found several specimens of this kind of trace fossils which is an unknown single animal radiating out to feed then returning to its same home location. 

[Ludwigia]

I think that your trace fossil is a Phycodes.