Unknown ordovician fossil

[PaleoOrdo]

I found this strange form in a stone from ordovicium. The size is less than 1 cm, never seen anything like it. Look almost as it is artificial but it is a real fossile. Any one have any idea what it can be? 

Martin

[Tidgy's Dad]

Crinoid columnal. 

[PaleoOrdo]

Is that one of the many parts of the stalk?

Is this form or specimen which I found of interest to keep for a researcher or is it very common? I did nt bring the stone from the field yet and only took a photo.

Thanks.

Martin

[Tidgy's Dad]

Yes, it's a stem segment. 

It's interesting, I like them, but they're fairly common generally, though I don't know the species for your area. 

Here's one of mine, a different genus (I think) Iocrinus from the Late Ordovician of Indiana, USA. They can be very common in some beds. 

 

[PaleoOrdo]

I can see the clear similarity with your specimen. I think the interesting part with mine is the clear forms or lines alone the edges.

Do you think this form, found in the same area, is also a crinoid columnal?

Martin

[Tidgy's Dad]

Yes. 

Another species.

The lines on the edge are articulation facets,

They only cover the crenularium (outer rim) of your specimen, on others they cover the whole columnal and on some, like my specimen, are not present at all. 

Your second type has a stellate lumen (star shaped hole in the centre). 

All these details can sometimes help identify the genus or species of crinoid. 

[PaleoOrdo]

Thank you very much for your excellent information. So as I understand the stalk of some species are round while others are round in the outer surface.

Do you, or anyone else, know of a book or website where I can find out which species or genus I found?

Martin

[Kane]

Discerning the geologic formation will be very helpful in directing your research. 

If found in Norway, the NGU (Geologic Survey of Norway) has several helpful resources: https://www.ngu.no/en/topic/geology-norway

 

[PaleoOrdo]

Thank you, Kane!

Martin

[ClearLake]

I know it is from a different area, but the volume by Moore and Jeffords is a great place to start in trying to ID crinoid columnals.  It is available online.

 

[PaleoOrdo]

By the litterature it seems difficult to determine the order, family and species only by the form of the colomn.

Martin