Crinoid?

[Allosaurus]

I can't quite figure out what this is if anything. Its from the Madison limestone in Montana (Mississpian in age).

At first I thought maybe some kind of crinoid but this specimen has ridges that are vertical not horizontal like most crinoids would normally have. It measures about 4 inches or so in length and was found with many brachiopods.

[izak_]

Probably a coral or bryozoan… Im not too sure though

[izak_]

I did also just notice some smaller crinoid segments, so they are there.

[Rockwood]

Perhaps an encrusting tabulate. .

[tmaier]

A nice "death assemblage" of many thing...

The big thing at the center might be a fan type of bryozoa?

http://www.google.com/images?q=fan+bryozoa&btnG=Search&hl=en&gbv=1

And look at the middle of the photo, right above the bryozoa-type object... a thing with what looks like five arms... Could it be?

And like dinoboy says, lots of crinoid bits.

And maybe in the center lower left, a piece of trilobite cephalon?

These assemblages are always so interesting to see.

[Allosaurus]

Five arms? I'm not seeing that, but if it is there, then maybe I have a fossilized alien!

As far as the trilobite cephalon goes, could it be something else? If I'm looking at the same thing there is another, much smaller one slightly above (and just above the bryzoa-thing) and to the left. When I look at that one it doesn't appear to be covered by anything and more or less like its just sitting on top the rest of the rock (unconnected to anything else). Could the cephalon have been separated from the rest of the trilobite, or is it something else?

It could be a fan bryozoa, but it does have similarities to a tabulate. However when I looked up pictures of an encrusted tabulate, I couldn't find any that matched the physical shape of what I have.

Not sure if it is worth mentioning, but when I went to this site this was the only piece with a bryozoa-thing. Everything else that I found was a crinoid or brachiopod (there were some really nice specimens, but I couldn't get them separated from the rest of the limestone; it was incredibly hard). Is there any way to further identify the crinoids? If so, I assume I'll need to post more up close, clearer pictures of them?

[tmaier]

Check out item #1. It's too blurry to make out in this photo, but I think it is worth a look. What is that?

Number 2 doesn't look like a crinoid segment, unless it is a honking big one. It's a piece of something, possibly the underside edge of a cephalon.

[Rockwood]

Encrusting forms of anything take the shape necessary to cover the surface being encrusted. The colony has no set shape. If it is a tabulate it would be a cross sectional view of the successive layers. The finer details of individual coralites are often lost in the fossilization process. The reason I went with coral over bryozoan is that the left side of it appears to have weathered enough to indicate that it was thicker than a fenestrate would have been.

Edited November 30, 2014 by Rockwood

[Allosaurus]

#1 looks like small pieces of crinoids that happened to settle next to each other. The picture makes them look like they're connected, but I I looked at it closely and I don't think so. Tomorrow when I have good light I can try to take a better picture of them.

Rockwood, what is a fenetrate? I'm not familiar with the word and when I looked up the definition I couldn't find anything.

[Rockwood]

Sorry, I get too used to ignoring spell check when I'm on here. I've edited in an s. Fenestrate should work better.

[Allosaurus]

Ah I see now. Thank you to everyone for their help.

[howard_l]

There is a long flattened rugose coral that is common in middle Mississippian rocks in Kentucky. They look a lot like what you have here but it is hard to tell from the pictures.

[Herb]

it looks like a coral on a piece of crinoidal limestone.

[JustPlainPetrified]

I like fenestrate bryozoan if images on google are anything to go by.