Mazon Creek Riddle

[Jones1rocks]

Can someone tell me what I'm looking at here? This is a split open Mazon Creek nodule with what I'm thinking is Cyclopteris, but if so, I cannot figure out what gave the fossil such depth in the concretion. Is it simply the way the concretion happened to open, or is some of the fossil hidden?

 

[trilobites_are_awesome]

@stats @RCFossils@Nimravis

Any ideas?

100% a fossil.

Edited October 25 by trilobites_are_awesome

[Fossildude19]

The pinnule may have settled on top of something else, that was already buried, yet bulging out.

Then it got fossilized on top of the other thing.  Maybe a shell or seed?

Only preparation from below on the other side would tell for sure.

[stats]

Could be one of the cases where the fossil formed on the outside of a concretion and then other layers built up.  When it opened, it broke through the outer layers and cupped out the "inner" concretion layers.  This isn't uncommon for concretions from Pit 11.  But, I've also seen for ones from other places.  I've also seen concretions with layers of fossils, fossils on the outside, and the worms of the Braceville spoil pile can wind through a concretion.

 

Some concretions are nice and well shaped, while others are ugly.  When they were forming, there was a sort of chemical cloud that hardened due to the iron and carboninate combining.  Do a search of "taphonomy of Mazon Creek".  People have long wondered how and why about the formation of the concretions of Mazon Creek and actully the late Pennsylvanian period.   I know of a few paleontologists interested in the question.

 

Here are just some of the known localities with fossils in siderite concretions.  There are more locations.

https://www.esconi.org/esconi_earth_science_club/2020/06/mazon-monday-5-mazoncreek-fossils.html

 

Cheers,

Rich

 

[RCFossils]

This is a single leaf of Sphenophyllum emarginatum.

 

[Nimravis]

41 minutes ago, RCFossils said:

This is a single leaf of Sphenophyllum emarginatum.

 

That is what I am seeing.

[Plantguy]

Great find and photos! 

Regards, Chris