Michigan Brownstone

[Bob Saunders]

I Found this  last week on what I believe some call Lake Michigan Brownstone ? 3 5/8th in x 4 inch.  Has Bryozoans and one I believe is a  brachiopod 15 mm wide attached to the side. 

Bob

[connorp]

I would agree with you on both. Probably won't be able to identify the bryozoa any more than that, they are notoriously difficult to ID. Maybe someone here recognizes the brachiopod. Nice find!

[Tidgy's Dad]

The brachiopod appears to be a rhynchonellid, but could possibly be an orthid.

Further determination could be difficult. 

[Bob Saunders]

Taxon: Rhipidomella sp. The images are a match and I have a specimen. Known to Michigan but my County in South West Mich.  is off the radar for fossils. I have dental tools so may see if I can clean it up some. 

Thank's, Bob

[Northern Sharks]

46 minutes ago, Bob Saunders said:

Taxon: Rhipidomella sp. The images are a match and I have a specimen. Known to Michigan but my County in South West Mich.  is off the radar for fossils. I have dental tools so may see if I can clean it up some. 

Thank's, Bob

The ribs are far too coarse to be Rhipidomella. Possibly Atrypa???

[FossilDAWG]

Doesn't look atrypid to me, as there are no frills ornamenting the ribs.  Also completely unlike Rhipidomella, the ribs are far too coarse for one thing.  What is the age of "Michigan brownstone"?  It's hard to make a positive suggestions (as opposed to just saying "nope that's not it) without any real geological context.  Age is a must, and actual formation (as opposed to local collector's slang) is very helpful.

 

Don

[Bob Saunders]

Thanks for the replies, I will try to get more information at our club meeting Wednesday. Around Holland, Michigan and around 80 miles north of Indiana. This is from a farm pond dig with a crane. Owner say's around 12-14 foot deep. Finding many Crinoids fossil plates. Along with much sand and too much clay. If this helps with a time period etc. 

[Peat Burns]

I'm guessing this may be Mississippian. Perhaps Coldwater Shale. Glacially transported. 

[Bob Saunders]

Thanks again, here are two from yesterday. 1st 4 5/16th   x 2 1/16th x 1 3/16th.    2nd  3 1/4 x 2 5/8 x 7/8th All of Michigan, Indiana is said to have been a warm shallow ocean south of the equator.                                                                          109.5 mm x 52.3 mm  x 4.76 mm                     82.5 mm x 66.6 mm x 22.2 mm   

[FossilDAWG]

Those latest pieces certainly could be Mississippian, with the fenestellid bryozoans, crinoid stem ossicles, and Leptanea brachiopod.  However, if it is glacially transported as Pete Burns suggested then one could still have a mix of ages and formations.

 

Don

[Shamalama]

On 10/28/2019 at 9:16 AM, Northern Sharks said:

The ribs are far too coarse to be Rhipidomella. Possibly Atrypa???

I agree with Kevin, Ribs are too coarse and there appears to be a shallow sulcus visible. My vote is for a Spirifirid of some sort.

 

As for the Bryozoans, if the rock is Devonian in age I would suggest either Thamnopora sp. or Thamnopytchia sp.