New Mazon Creek Collection

[bigred97]

Here is a bivalve found in Pit 11, I believe Mazonomya mazonensis. I have a number of other specimens that broke into many fragments when they opened in freeze thaw, and some day will see if I can piece some of those together. But this one luckily broke very cleanly across an even plane.

 

[bigred97]

[bigred97]

[Mark Kmiecik]

That's a keeper! And a showy nodule as well. You could sell it online as a Clamosaurus egg with embryo. 

[Tidgy's Dad]

A beaut. 

[deutscheben]

Nice one! 

[bigred97]

Thanks, @Mark Kmiecik @Tidgy's Dad and @deutscheben! Clamosaurus - LOL!

[bigred97]

I have found what I believe are 5 specimens of Cyclus americanus, all from Pit 11. @stats if I recall you really like these guys, so I didn't want you to miss it.

Here is #1, which is somewhat hard to make out but I think I see the line up the middle and at least the start of one of the antennae:

 

Next is #2, which is my smallest. It is on the "end" of a long, thin concretion, and these kind almost never have anything in them. This was the exception. Unfortunately the other side sort of crumbled away in freeze thaw, but I like this little guy:

 

 

[bigred97]

[bigred97]

#3 is my largest. It has a really pronounced center ridge, or line up the middle. You can also make out the back two appendages but they aren't terribly clear.

[bigred97]

[bigred97]

[bigred97]

I think #4 is my favorite so far. It has a lot of detail including the center line and clearly visible hind appendages (fins?):

[bigred97]

[bigred97]

[bigred97]

 

I forgot to mention, in specimens #2 and #4, I see little holes at different spots. I'm curious about them. Does anyone know what those might represent? I've never seen holes like that on any other Mazon Creek fossil.

[bigred97]

Finally #5. This one I found unopened but it opened very quickly and seemed somewhat damaged inside, making me think that it was almost open for a while and was damaged in a similar way as if it had been opened. But what makes me curious about this one is that it seems to have some type of structure to the body that I haven't seen in any others. It almost looks like fibrous material, running from the outer edge of the shell towards the center, but stopping somewhat away from the center in a uniform pattern. Maybe this is just damage to the fossil? But it made me wonder if it's possible that this is the internal structure of the creature that I'm seeing?

[bigred97]

[bigred97]

[bigred97]

Final Cyclus pic for now, until I find another one! Chris

[Tidgy's Dad]

I love Cyclus americanus. 

The one with appendages is particularly splendid. 

And the last one very intriguing. 

[deutscheben]

That is a very nice collection of Cyclus, you have some with quality detail and preservation there. Regarding the structures you noticed- I have also seen that the holes around the perimeter are typical for the Cyclus I have. The paper describing the Mazon cycloidea can be read online: https://www.researchgate.net/publication/254788906_Mazon_Creek_Cycloidea and talks about the carapace having bumps, so maybe that's what they are. 

 

That structure on the last one is interesting, I wonder if it is revealing some internal structure or partial decomposition? For a look at some similar structures and some amazingly preserved Cyclus from elsewhere, check out @t-tree's post:

 

http://www.thefossilforum.com/index.php?/topic/103247-carboniferous-cyclus/

[deutscheben]

Actually! I finished reading through the Mazon Creek Cycloidea paper and I think your last one may not be a Cyclus at all, but rather Halicyne max. The overall shape and the anatomy all matches, and the paper depicts multiple examples with visible gill lammelae or rugae that look just like the structures in question. Another nice find!

[bigred97]

Wow, @deutscheben are you a detective in real life? Awesome find! I looked at that paper and page 278 in the upper left picture looks remarkably similar. How interesting. And to think that at one point I was thinking that was kind of a ruined specimen and maybe when I had a number of other Cyclus specimens I might want to toss it! But those structures always kind of puzzled me, they looked to have some symmetry. Gosh am I thankful for your sleuthing skills!

 

+1 to my Mazon Creek species count! Chris

[stats]

You remembered correctly!  One of my favorites.  Nice specimens, Chris!

 

Cheers,

Rich