2nd Attempt at ID

[minnbuckeye]

I had attempted once before to ID these small creatures in the matrix of the Platteville Ordovician rock of SW Wisconsin. Hopefully this time will yield some results. They are small, less than 1/2 inch in diameter. 

 

 

 

Here are the most detailed two.

 

 

 

 

[minnbuckeye]

As my mind goes over possibilities, I come back to a cephalopod found in the same formation which has similar external ornamentation. Here is a Zitteloceras cephalopod found during the same fossil hunt that these were found. It measures 2 inches in length, much larger. And Zitteloceras lacks the spiral. Still, could these be baby cephalopods??

 

 

 

 By the way, Ptychodus 04 was kind enough to remove the matrix from this cephalopods ridges making it a beautiful specimen. Thanks for the help.

[minnbuckeye]

anyone?

[ynot]

I would say that they are baby ammonites. But they could be baby snail just as easily.

[JohnBrewer]

What stunning hash plates!

 

while some do look like ammonites it's a little too early so as Tony says they might even Gastropods. 

[minnbuckeye]

Thanks for the replies. They occur quite frequently so I figured someone would recognize them.

[Peat Burns]

At first glance, they reminded me of the gastropod Phragmolites dyeri, but the ornamentation doesn't quite match.  There appears to be a number of species in that genus.  It might be worth seeing if any match.  Otherwise, I've got nothing 

[minnbuckeye]

I tried searching Phragmolites and get nowhere. Is it spelled correctly or is the problem on my end?

[Peat Burns]

6 minutes ago, minnbuckeye said:

I tried searching Phragmolites and get nowhere. Is it spelled correctly or is the problem on my end?

That's the correct spelling.  Make sure Google doesn't redirect you to the invasive grass Phragmites.. You have to click the "search instead for phragmolites" when it tries to redirect to phragmites.

 

Not a match, but this is what initially came to mind.  Maybe a similar species?

 

[minnbuckeye]

Wow!!! Those look very similar. I will research a bit. Thanks for the direction to an ID!

[Peat Burns]

31 minutes ago, minnbuckeye said:

Wow!!! Those look very similar. I will research a bit. Thanks for the direction to an ID!

My pleasure.  Main difference in surface structure is that P. dyeri is cancellate, while your specimen doesn't appear to be.

[Peat Burns]

Here's another genus that might be worth exploring:

Edit:  this one doesn't look like it occurs in North America, so not likely a candidate.