What Are These Cylinders?

[rwise]

Here are some others that I need help with from Jacksboro, TX, Pennsylvanian, Graham formation, fins shale......These are some examples of items that are quite common in this area.....They are cylindrical, with a definite center core running thru the specimen and seem to have "growth lines" on the sides, almost like orothocones, but the lines are not as straight. All sizes are abundant.

1. 2.

3. 4.

5. 6.

7 . 8 .

I have had several suggestions of what they are, but none are in agreement. Again, Thanks in advance for your help.

[RyanNREMTP]

5 and 7 look like crinoid stems.

[amour 25]

Something that was in a Burrow that got fossilized?

I see what you say about Crinoid but I always see the rings around the stem , coral maybe , bryozoan maybe?

Jeff

[Plax]

straight cephalopod? Not seeing the siphuncle on all the segments though. Just a guess of course....

[Ptychodus04]

They all look like cephalopod chamber sections to me.

[gturner333]

I think they are burrows, R. They are pretty common out there. The straight cephalopods are usually better defined.

[erose]

I think they are burrows, R. They are pretty common out there. The straight cephalopods are usually better defined.

I agree. Definitely not crinoid. You can find these in situ going down into the layers.

[rwise]

Why would burrows fill in kn layers with several concentric circles in the center....i think it must be something else

[BobWill]

This makes the second unresolved cylindrical fossil found at Jaxbro. Texas Fossil Hound posted some a while back that had linear groves and occasional concentric divisions. Roz and Lance and I posted ours and some were cut open revealing the same layering like a kind of long concretion. I find these a lot there. Some have the segmentation, others not but they do not resemble the typical coprolites, crinoid stems, or orthocone cephalopods found there. That's the odd part, most fossils from there are so well preserved. They come out of the shale without excessive wear and clean up with soap and water so you know what they are without question. These things need a look, in hand, by a professional who can make a determination without all this guesswork.

[rwise]

I agree Bob...maybe we can talk to someone at the society....i have several more examples and i know others do too...

[Plax]

I read somewhere, I think MacFall's Fossils For Amateurs, that fossils can grow, like popcorn, under certain conditions. I suspect that this fossil is either a straight ceph or a crinoid that has grown in this manner, some detail is lost of course. Wish I had my references at work.......

[fossilized6s]

I read somewhere, I think MacFall's Fossils For Amateurs, that fossils can grow, like popcorn, under certain conditions. I suspect that this fossil is either a straight ceph or a crinoid that has grown in this manner, some detail is lost of course. Wish I had my references at work.......

Yes, this is true. I have found a few crinoids that have undergone this process. But they usual don't stay so flat. Mine are basically rounded everywhere, like an obese crinoid.

[outdoorfunblonde]

Yes, actually ALL of those are crinoid stem sections. They just so happen to fall apart like that sometimes.

[BobWill]

I've seen different ways crinoid stems can be preserved but like everything else found there, the ones from Jacksboro all look like they just fell over yesterday. There's nothing in between to suggest the different levels of preservation you would need to approach these almost featureless blobs.

[Macrophyseter]

looks like a vertebrae to me.....

[Gen. et sp. indet.]

Look like cephalopods to me.

[Rockwood]

# 2 + 7 look like textbook cephalopod fossils to me.

It also occurs to me that cephalopod shells could make good burrows, perhaps explaining some of the distortion.

Edited February 1, 2015 by Rockwood

[BobWill]

As with the crinoids, you almost have to see in hand how beautifully the cephalopods from here preserve to see why there's any question about these. The central core does look like a siphuncle but the "sutures" are often not spaced correctly and the septa are not as smooth as what's seen on typical cephs from here. The other odd bit is the concentric layering these often have which doesn't show well in these pictures and shouldn't be seen on a cephalopod. We need to hear from Roz or Lance on this one. I'm pretty sure they would have some of these. Of course they could be a particular species that doesn't hold up well when fossilized and isn't listed in the literature about this site.

[Gen. et sp. indet.]

And what about Lisegang rings-concretions?

[Rockwood]

Bob,

Have any of you considered the possibility that these could be both cephalopod shells and coprolites ? Fish do usually swallow their food whole.

[BobWill]

Cephrolite sp. Oh, great ! Now somebody's got to write a stinkin' paper!

[Rockwood]

Naw, just food for thought. We don't need no stinking paper. The idea came from a fossil that was shown to me which had been identified as a lizard but was also thought to be a coprolite.

[Auspex]

My impression is that what I see in the images is most consistent with not-too-well-preserved cephalopod casts.

[BobWill]

Going through a fishes gut might explain the wear on the outside compared to the usual from there, but I don't know about the rough texture on what would be the septa. Most of the exposed chamber walls from Jacksboro cephs are not just smooth but many have a sheen to them like they were polished. Also these "septa" are flat, the usual are convex or concave and the edge at the outer wall is always sharp, not worn like these. I believe Erose has collected there and he seemed to concur. Help! Lance! Roz?

Edited February 2, 2015 by BobWill

[DPS Ammonite]

Mystery solved?

I think that these are fragments of a giant scaphopod. I found a reference, of which I could only see a small portion thanks to a pay wall, in the Journal of Paleontology, v 53, no.1, p. 164-168, January 1979 entitled:" New Specimens of Prodentalium Raymondi Young (Scaphopoda) From The Pennsylvanian of Texas" by Tenery. If anyone can get a copy of the article or a photo/ drawing of the scaphopod please post it or PM me, I'd love to see it. Various internet sources mentioned that Prodentalium reached lengths of 200-300 mm and 35 mm in width. What are the dimensions of the largest piece you have found at Jacksboro or other Pennsylvanian sites?

After considering sponges, corals without prominent septa and wood/plants, I noticed these fossils had great similarity to scaphods such as Dentalium. They both have hollow centers, longitudinal ribs and growth rings that are irregular in thickness and are often oblique to the longitudinal direction of the scaphopods. The National Audubon Guide to North American Fossils says that "Prodentalium is covered by oblique growth lines and fine longitudinal ribs, generally with a slightly zigzag alignment."

See photos of specimen collected at Jacksboro in the Finis Shale that shows trace of longitudinal ribs and irregular growth lines that are sometimes oblique to ribs. The grown rings in my specimens are too irregular to be either crinoids disks or chambers in a cephalopods. Some of the growth lines intersect each other similar to cross bedding in dune sandstone.