Brittlestar identification.

[Mctapmonkey]

I picked up this Brittlestar recently at a fossil fair, but when I tried to research it later the Cyphaspis label seems to refer to a Trilobite sp.

Can anyone clarify what I have here?

[Miocene_Mason]

Ophiura sp. ?  Or maybe a very strangely shaped trilobite

[doushantuo]

More detail would be nice ,particulary of the oral disk

[Sagebrush Steve]

15 minutes ago, WhodamanHD said:

Ophiura sp. ?  Or maybe a very strangely shaped trilobite

I think you mean Ophiopetra.  I have a similar specimen from the Solnhofen formation in Germany.  This one may have had some paint applied to the center disk (I can't tell for sure) but it is a very nice specimen.

[doushantuo]

like this,I suppose

[Sagebrush Steve]

2 minutes ago, Sagebrush Steve said:

I think you mean Ophiopetra.  I have a similar specimen from the Solnhofen formation in Germany.  This one may have had some paint applied to the center disk (I can't tell for sure) but it is a very nice specimen.

Or it could be Ophiura, they apparently both show up in the fossil record.  Perhaps an expert can say for sure.

[doushantuo]

It does have a aplocomid vibe,BTW

[Miocene_Mason]

11 hours ago, Sagebrush Steve said:

I think you mean Ophiopetra.  I have a similar specimen from the Solnhofen formation in Germany.  This one may have had some paint applied to the center disk (I can't tell for sure) but it is a very nice specimen.

 

11 hours ago, Sagebrush Steve said:

Or it could be Ophiura, they apparently both show up in the fossil record.  Perhaps an expert can say for sure.

I'm not sure, Ophiura is just what most Sellers say, although I'm not sure the trustworthiness of them.  I hope there is an Paleophiuroidologist that can help somewhere on the forum.

[Miocene_Mason]

This paper may be a good help, I wasn't able to extract an answer from it, but maybe someone more knowledgeable on the subject will.

[Sagebrush Steve]

1 hour ago, WhodamanHD said:

This paper may be a good help, I wasn't able to extract an answer from it, but maybe someone more knowledgeable on the subject will.

Here is a link to an article with some good photos of Ophiopetra lithographica from the Solnhofen formation in Germany.  I now realize the arms of the specimen in question don't match Ophiopetra very well, so it's probably something else.  Not sure what.

http://woostergeologists.scotblogs.wooster.edu/2013/03/10/woosters-fossil-of-the-week-a-brittle-star-from-the-upper-jurassic-of-germany/

[doushantuo]

I posted a pic out of the first reference that page mentions,Enay//Hess.

BTW,I've got (probably)ALL of Hess's ophiuroid studies

I've got a pretty good idea of ophiuriod systematics.

The fossil shown is the spitting image of an as yet unnamed ophiuroid fossil from the Triassic of Lombardy

[doushantuo]

Hess(SJG,2008):

Subfamily Ophiopetrinae new Diagnosis. – Arms spines robust, erect, inserted on distinct
sockets; lateral arm plates not striated.
Ophiopetra ENAY & HESS 1962
Diagnosis. – Teeth conical; 3–4 arm spines, length up to two arm
segments; dorsal arm plates triangular with convex distal edge,
in contact only in proximal part of arms.
Ophiopetra lithographica ENAY & HESS 1962
Diagnosis. – Teeth conical, increasing in size dorsally and becoming
flattend; six oral papillae, proximally four leaf-like papillae,
distally two conical papillae; surface of lateral arm plates
slightly concave; arm spines longer than arm segment; adoral
shields barely in contact; plate bar-like.

[doushantuo]