Bumpy Unknown in need of Identification

[minnbuckeye]

I need opinions on whether this bumpy unknown from the Ordovician/ Galena of NE Iowa is coral, bryozoan, or something completely different. I lean towards and hope for the latter. A dozen years of heavily hunting this exposure has produced only this solitary specimen. There are images of the positive and negative sides. Also notice, that there is no depth to this fossil. It appears to be wafer thin. I will look forward to the responses! 

 

 

 

 

 

 

 

 

[Jaybot]

Part of shrimp burrow, possibly.  Reminds me of some I found in WY, Frontier fm.

 

Not my specimens, some examples from the web:

 

 

 

 

 

 

 

They remind me of corn.....

 

 

[Jaybot]

If you'd like, I can upload a pic of the ones I found in WY 

[minnbuckeye]

@Jaybot, looks similar but were there shrimp in the Ordovician?

 

Actually, I found this:

      Shrimp evolved over a long period of time, with the oldest reliable fossils dating back to the Triassic period, around 200–250 million years ago. However, the origins of shrimp may go back even further, with some evidence suggesting that they may have evolved as far back as the Paleozoic era, around 360 million years ago

[Rockwood]

This looks a bit like the eggs of apple snails. Snails were around in the Ordovician. 

[doushantuo]

bit of a receptaculid?

[TqB]

Looks like a piece of Cyclocrinites, a calcareous alga. (So a receptaculitid sort of thing, depending on how you classify them.) 

A Silurian (Llandovery) one:

[doushantuo]

that's some awesome photography right there, great specimen.

Edit:

Minn , awesome find, cyclocrinitids are perceived** to be good "facies fossils"/ ecological indicators

 ** by those who go for an algal affinity 

 

 

Edited November 4 by doushantuo

[minnbuckeye]

Thanks for the responses! I knew it was something that I do not ordinarily find. And it does not look like the recepticullitids, Fisherites oweni or Ischadites iowensis, that commonly exist in the Galena.

[minnbuckeye]

4 hours ago, doushantuo said:

cyclocrinitids are perceived** to be good "facies fossils"/ ecological indicators

 

@doushantuo  Could you explain this to a lay person like me. Much appreciated!

[doushantuo]

A facies fossil is a fossil that is thought to be indicative of certain physiographical, sedimentological, or climatic conditions, both preburial, and postburial.

 

Cyclocrinitidae are found in sediments thought to be fully marine,which in itself is a sort of salinity indicator, unless one supposes a wholly different geochemistry of Paleozoic marine waters .

 

If they were dasyclad  algae, their habitat would be the zone where the quantity of sunlight is sufficient for the algae to photosynthesize, and thrive.

The temperature can't be too low either.

 

Of course, how deep sunlight penetrates in sea water is very much correlated with the quantity and quality of the sediment in the water column, and/or the turbulence of the water.

 

Now dasyclads are generally found in shallow, clear water (which would make their habitat the shallow continental shelf ), but rare deep water occurrences are known. Generally cyclocrinitids are found within approximately 20 degrees north and south of the paleo-equator, which, given reasonable insulation parameters and a atmosphere comparable to the current one, would make their distribution "circumtropical".

 

Sometimes juvenile (smaller) "thalli" are found accumulated, and these are presumed to be swept together by bottom currents.

 

Let me know when I haven't been clear!!!

 

 

[minnbuckeye]

@doushantuo, Your response is CRYSTAL CLEAR! Thanks for the in depth explanation.

[Jaybot]

Interesting!  Neat looking algae, nice find @minnbuckeye

[doushantuo]

for "insulation" in my monday 2.30 post read:  "INSOLATION"

That error annoys me no end

 

A necessary remark: past solar luminosity *parameters are not known of course,there are indications of change in that parameter 

*'total light output "