Ordovician donut from Maysville

[connorp]

I found this strange specimen in the Upper Ordovician Fairview Formation outside of Maysville, KY. The thing attached to the donut looks like it could be a crinoid holdfast, but if so I can't recall having seen a similar one from the Cincinnatian. But what might the donut be? A large trace fossil? A strange sedimentary structure? I really have no idea, I've never seen anything similar before.

 

 

[abyssunder]

Stromatoporoid ?

[Ludwigia]

4 hours ago, connorp said:

But what might the donut be?

 

Prasopora bryozoan perhaps?

[fifbrindacier]

Worn cephalopod ?

[minnbuckeye]

17 hours ago, Ludwigia said:

Prasopora bryozoan perhaps?

Size seems to eliminate Prasapora. My largest to date MAY be about 4".

  

Mike

[Ludwigia]

2 hours ago, minnbuckeye said:

Size seems to eliminate Prasapora. My largest to date MAY be about 4".

  

Mike

 

Oops! I thought the scale was in centimeters.

[minnbuckeye]

Just a possiblitiy:

            Large trepostome bryozoans are common in the formation. Here is one from the University of Wooster. Though I do not see definitive direct evidence of bryozoan in Connor's specimen, maybe due to erosional processes, the upper right (darker area) looks very similar to the borings of Trypanites that occur in the area's bryozoans, as seen in the sample from Wooster.     

http://woostergeologists.scotblogs.wooster.edu/files/2017/03/1-Trepostome-585-Bellevue.jpg

Edited November 10, 2021 by minnbuckeye

[abyssunder]

1 hour ago, minnbuckeye said:

Just a possiblitiy:

            Large trepostome bryozoans are common in the formation. Here is one from the University of Wooster. Though I do not see definitive direct evidence of bryozoan in Connor's specimen, maybe due to erosional processes, the upper right (darker area) looks very similar to the borings of Trypanites that occur in the area's bryozoans, as seen in the sample from Wooster.     

http://woostergeologists.scotblogs.wooster.edu/files/2017/03/1-Trepostome-585-Bellevue.jpg

Are you referring to this one? 

[minnbuckeye]

Thanks! Yes, somehow my picture disappeared!! Likely my mistake. 

[connorp]

I discussed this specimen with a couple local collectors, and the consensus seems to be that it's probably a sponge of some sort. Perhaps a stromatoporoid as was suggested here. Unfortunately the specimen shows signs of weathering and thus there is no surface detail on the doughnut, making positive identification challenging. I found an anecdotal account in a book A Sea without Fish: Life in the Ordovician Sea of the Cincinnati Region (Life of the Past) describing a similar specimen, unfortunately there are no accompanying pictures and it is unclear if the specimen discussed is accessioned in a museum somewhere.

 

Regardless, it is quite an interesting specimen. A local museum reached out and indicated they would be interested in this specimen, and I will be bringing it down to donate next time I head down to Cinci.