Ordovician Maclurites?

[tombk]

Hi all, I'm on vacation about 8 miles east of Galena Illinois. I was going to wait until I got home to post a travel piece. I'm too excited to wait, though. I had reached out to a few rock/fossil clubs asking whether there are any known collecting sites around here, and nobody knew of any. There's a road-cut near where I'm staying, and I found what I think is a maclurites fossil! It's not in the best condition, but not bad for about 450-million years old! From what I can tell, the exposed rock around here is in the Galena Group (Trenton Limestone). One app says the stratigraphic unit is the Millbrig k-Bentonite bed. Well, here are some pics, and I hope to post more when I get home and get settled. (The fossil was exposed, and I've done no prepping beyond some light brushing off of dirt.)

 

The domed side:

 

The flat side

 

 

"Face-on" view

 

 

I researched this fossil on TFF and saw that it is a favorite of @Bev

[Carl]

I can't say I know much at all about gastropods, but it looks like Maclurites to  my eye. Let's see what @minnbuckeye says.

[tombk]

30 minutes ago, Carl said:

I can't say I know much at all about gastropods, but it looks like Maclurites to  my eye. Let's see what @minnbuckeye says.

I don't know much about gastropods either, but Maclurites are the only ones I found from the Ordovician that are flat on one side. 

[Tidgy's Dad]

Yup. Decent sized Maclurites. 

Nice find. 

[connorp]

Yes, Maclurites from the Wise Lake Formation of the Galena Group. Maclurites is not super common in Illinois. It is very prevalent in the Wise Lake of NE Iowa and  the Stewartville (Wise Lake equivalent) of SE Minnesota, but in northern Illinois Liospira is much more common (Liospira looks similar to Maclurites but coils in the opposite direction).

[Tetradium]

1 hour ago, connorp said:

Yes, Maclurites from the Wise Lake Formation of the Galena Group. Maclurites is not super common in Illinois. It is very prevalent in the Wise Lake of NE Iowa and  the Stewartville (Wise Lake equivalent) of SE Minnesota, but in northern Illinois Liospira is much more common (Liospira looks similar to Maclurites but coils in the opposite direction).

Also Liospira tend to be much smaller than this lol.  1 inches across ones tend to be somewhat common in Ordovician twin cities. 

[tombk]

I’ve dose some buffing and cleaning of this specimen. Here’s a pic of the basal side as it looks now. 
 

[Bev]

Nice find! You may well have a Maclurites crassus that are not even that common here! I say this because the back is very flatish compare to a "normal" Mac, I was told there are over 30 species of Macs and they are an index fossil for the Ordovician - meaning they only lived in the Ordo. Plus once you cleaned the Mac up on the front I think you could take a dremel tool to it and carefully carve out the inner whorls. Look at my picture to the left and how you can look right through this Maclurites crassus. They crawled along the sea floor on the flat side and they could change sexes! This is of course an infilled cast of the original snail. They are my favorite gastropod! My lucky day every time I find one!  :-D  Congratulations on a Great Find!  :-D