Question for the Texas Crinoid-philes

[dre464]

I have what I think are somewhat technical questions for those more knowledgeable than myself. Wandering the wonderland that is the Wilson Clay Pits of central Texas, you tend to run across numerous examples of these fossils...

The above photo shows only one side of the spines. The other side is smooth...

In the University of Texas Bulletin #2132 Stratigraphy of the Pennsylvanian Formations of North-Central Texas (1921), Plummer and Moore have them identified as Hydreionocrinus sp. spines. So, for my first question, is Hydreionocrinus still a valid genus? If not, what is the new name?

While I knew that they were spines, I have been confused by the placement on the animal itself. I had seen reconstructions of Delocrinus sp. with the spines radiating from the top of the cup. But these looked different. I then stumbled across a paper from the Ohio Journal of Science called TEGMEN ROOF OF PLAXOCRINUS MOORSI (WHITFIELD) by J.J. Burke. He describes very similar plate spines on the tegmen roof of the anal sac of Plaxocrinus sp. Below is the figure in his paper that caught my attention.

So, I tried a quick sketch of what I thought Hydreionocrinus might look like.

Am I correct in assuming the spines are located at the tip of the anal sac? I'm guessing that the textured plate surface is attached to the sac. Is there a complete Hydreionocrinus calyx that I could look at (I'm kinda visually minded...)?

I'm sure the drawing is out of proportion. I was drawing from memory and imagination more than anything. It could be a crinoid chimaera...

Your comments are welcome and appreciated...

[BobWill]

I can't help you with the names but you are correct about the placement. The axial plate spines that can occur around the top of the cup only have one straight attachment surface. I have found both kinds at WCP. Yours are from the anal tube.

Edited May 19, 2016 by BobWill

[dre464]

Thanks Bob...

I'm curious. Are both of your spines in the pictures from the same type of crinoid? I've seen some reconstructions that have spines in both positions. I'm just wondering if the spines that I have with the straight attachment surface are from the cup of Delocrinus, or from the cup of Hydreionocrinus.

[doushantuo]

i found some stuff you might like:

https://etd.auburn.edu/bitstream/handle/10415/3805/Sarah%20Sheffield%20Final%20Thesis.pdf;sequence=2

[dre464]

Thanks doushantuo! That's a wealth of information!!!

[BobWill]

Thanks Bob...

I'm curious. Are both of your spines in the pictures from the same type of crinoid? I've seen some reconstructions that have spines in both positions. I'm just wondering if the spines that I have with the straight attachment surface are from the cup of Delocrinus, or from the cup of Hydreionocrinus.

I always find the different spines separately so I don't know if they are on the same crinoid. Even the cup plates I find are disarticulated except for the occasional base consisting of five plates.

[abyssunder]

Not a complete Hydreionocrinus calyx (only with one spine attached) is in the picture below, also, compared with the other, you could see the difference between the two type of spines, as Bob exemplified as well. http://pennsylvanianatlas.org/genera/hydreionocrinus/

Also here is a document describing Hydreionocrinus uddeni n. sp., including (in Figs. 3-5) -Three views of a spinous plate from the summit of the ventral sack, probably belonging to this species. (Pal. Coll. Walker Museum, No.13363), in S. Weller. 1909. Description of a Permian crinoid fauna from Texas. Journal of Geology 17:623-635 Description of a Permian Crinoid Fauna from Texas - Stuart Weller.pdf
Hydreionocrinus uddeni belongs to Neozeacrinus (Neozeacrinus uddeni Weller 1909) according to G. D. Webster and N. G. Lane 1967.