Mystery circular fossil with radial ridges and grooves

[abyssunder]

... Can we get a focused view of the side with question mark, in approx the same position as in the cropped picture? (Sorry asking for another pic, but may help.)

 

[EMP]

2 hours ago, Fossildude19 said:

 

No need to apologize.  

But I'm honestly interested in finding out why you are sticking with that assessment. What are you basing your opinions on?

 

Do you have an ID for that photo?

 

I really would just like to get to the bottom of this.  

I'm just looking for your supporting evidence, and I am having a heck of a time finding anything similar in My google searches.  

That's a polyp for the coral Heterophrentis sp.

 

Most of the crinoids I've found in that formation are very small portions of the stalk, none of which are that large. The rock looks like the upper siltstone bed of the Mahantango, which would have been a pretty shallow nearshore deposit unlike the pictures of previous crinoids shown here, which inhabited shallow reef like environments. The only other crinoid from those rocks I found was whole, but the entire thing is maybe two inches long not including the arm(s).

 

The coral polyps, however, are in the same size range and are shaped just like that one with the conical bit. It's important to remember that the fossils in this shale are molds/casts (not wanting to start that discussion again!) and are fairly fragile and brittle, so if that were the preservation of the inside of a crinoid column it would be incredibly uncommon for the type of preservation most prevalent in those rocks. I'm not saying it doesn't happen, just that more often then not preserving something as delicate as that wouldn't be something you'd just find (of course you can get flakes of shale bits on the larger brachiopods, but fine details are not really preserved).

 

The cropped picture shows the conical section I'm talking about. That screams coral polyp to me.

[Fossildude19]

30 minutes ago, EMP said:

That's a polyp for the coral Heterophrentis sp.

 

Most of the crinoids I've found in that formation are very small portions of the stalk, none of which are that large. The rock looks like the upper siltstone bed of the Mahantango, which would have been a pretty shallow nearshore deposit unlike the pictures of previous crinoids shown here, which inhabited shallow reef like environments. The only other crinoid from those rocks I found was whole, but the entire thing is maybe two inches long not including the arm(s).

 

The coral polyps, however, are in the same size range and are shaped just like that one with the conical bit. It's important to remember that the fossils in this shale are molds/casts (not wanting to start that discussion again!) and are fairly fragile and brittle, so if that were the preservation of the inside of a crinoid column it would be incredibly uncommon for the type of preservation most prevalent in those rocks. I'm not saying it doesn't happen, just that more often then not preserving something as delicate as that wouldn't be something you'd just find (of course you can get flakes of shale bits on the larger brachiopods, but fine details are not really preserved).

 

The cropped picture shows the conical section I'm talking about. That screams coral polyp to me.

 

Thanks for your explanation. I'm not convinced, but I can understand where you are coming from, now.  

 

[abyssunder]

If I'm correct, Heterophrentis is a solitary rugose coral (horn coral), so it should have a fossula which I couldn't see in any of the specimens from the matrix. Enallophrentis

[BobWill]

Is there any chance you could chip away some of the matrix on one of those? Maybe choose one that's near the edge of the rock so there's not a lot of matrix to remove. If the rock is too hard don't ruin your specimen but this would settle the matter with only a small portion exposed and you could put a proper label on it. Sometimes a small chisel, like 1/4" or so, and a mallet will do the trick. Point the chisel away from the fossil and see if it will pop off in the right place. If not some limestone will respond to light abrasion with a pin vise or x-acto knife blade.

[Rockwood]

14 hours ago, AlexT said:

 

  I'd love to know if the same species endured for 40 million years.

I don't think columnal morphology would be a reliable feature for this purpose anyway. I would be more likely to expect different species to have columnals that were indistinguishable.

Of torse I tood be wong.  

[doushantuo]

Any remnants of stereom visible?Or is that a stupid question?

[doushantuo]

Heterophrentis

From Stumm,vol XVII/10)contr.to sc.(species ferronensis):

Corallum simple, ceratoid, ranging from 29 mm to 62
mm in length and from 25 rnm to 41 mm in maximum diameter. Walls
ranging from thin to thick with typical exterior annulations. Calyxes relatively
shallow, bowl-shaped, with relatively flat axial regions and low sloping
peripheral regions. Fossula wide, prominent, situated on convex side of
corallum or at an oblique angle to that position. Major septa extending
from one-half to two-thirds distance to axis; minor septa averaging about
one-third the length of major. Major septa extending nearly to axis in
neanic stage. In transverse section septa ranging from 86 to 98; cardinal
fossula well defined. In longitudinal section tabulae complete or incomplete,

relatively horizontal axially, bent downward in peripheral region.

 

ditto(gregaria):

Description.-Corallum simple, wide ceratoid to trochoid, lectotype
measuring 55 mm in length and 46 mm in maximum diameter. Epitheca
with distinct, irregularly set annulations. Septa1 furrows clearly defined.
Calyx oblique, very shallow, bowl-shaped. Cardinal fossula on convex side of
corallum, very prominent, attaining greatest width of 9 mm near peripheral
region. Cardinal septum in base of fossula. Counter and alar septa not
distinguishable from metasepta. In transverse section septa 100, major
extending to, or nearly to, axis. In the sectioned paratype major septa of
counter quadrants forming axial whorl; minor septa extending axially with
average length of 3 mm. In longitudinal section tabulae incomplete, flat or
distally convex.

trying to get at/to Oliver(1993) now

 

edit: i shouldn't really try to understand siphonophrentid taxonomy.

I hear sirens,and they're coming for me.

The walls of my home now have a sclerenchymous texture...

By bye ,everyone

 

 

 

[TqB]

39 minutes ago, doushantuo said:

Heterophrentis

From Stumm,vol XVII/10)contr.to sc.(species ferronensis):

Corallum simple, ceratoid, ranging from 29 mm to 62
mm in length and from 25 rnm to 41 mm in maximum diameter. Walls
ranging from thin to thick with typical exterior annulations. Calyxes relatively
shallow, bowl-shaped, with relatively flat axial regions and low sloping
peripheral regions. Fossula wide, prominent, situated on convex side of
corallum or at an oblique angle to that position. Major septa extending
from one-half to two-thirds distance to axis; minor septa averaging about
one-third the length of major. Major septa extending nearly to axis in
neanic stage. In transverse section septa ranging from 86 to 98; cardinal
fossula well defined. In longitudinal section tabulae complete or incomplete,

relatively horizontal axially, bent downward in peripheral region.

 

ditto(gregaria):

Description.-Corallum simple, wide ceratoid to trochoid, lectotype
measuring 55 mm in length and 46 mm in maximum diameter. Epitheca
with distinct, irregularly set annulations. Septa1 furrows clearly defined.
Calyx oblique, very shallow, bowl-shaped. Cardinal fossula on convex side of
corallum, very prominent, attaining greatest width of 9 mm near peripheral
region. Cardinal septum in base of fossula. Counter and alar septa not
distinguishable from metasepta. In transverse section septa 100, major
extending to, or nearly to, axis. In the sectioned paratype major septa of
counter quadrants forming axial whorl; minor septa extending axially with
average length of 3 mm. In longitudinal section tabulae incomplete, flat or
distally convex.

trying to get at/to Oliver(1993) now

 

edit: i shouldn't really try to understand siphonphrentid taxonomy.

I hear sirens,and they're coming for me.

The walls of my home now have a sclerenchymous texture...

By bye ,everyone

 

 

 

 

Good stuff, note in particular the wide fossula in both of these...

[doushantuo]

the radial structures are pretty straight....

judging from the pic,that is.

 

[AlexT]

19 hours ago, abyssunder said:

... Can we get a focused view of the side with question mark, in approx the same position as in the cropped picture? (Sorry asking for another pic, but may help.)

 

Yes I will get that hopefully this weekend.

[AlexT]

17 hours ago, BobWill said:

Is there any chance you could chip away some of the matrix on one of those? Maybe choose one that's near the edge of the rock so there's not a lot of matrix to remove. If the rock is too hard don't ruin your specimen but this would settle the matter with only a small portion exposed and you could put a proper label on it. Sometimes a small chisel, like 1/4" or so, and a mallet will do the trick. Point the chisel away from the fossil and see if it will pop off in the right place. If not some limestone will respond to light abrasion with a pin vise or x-acto knife blade.

I can try.  

[AlexT]

8 hours ago, doushantuo said:

Any remnants of stereom visible?Or is that a stupid question?

I have a dozen or so pieces with probably hundreds of the disc imprints, but nothing that I recognize as a stem or stem imprint with the exception of one strange fossil (too narrow to be the stem associated with many of the discs, but maybe ok for some of the smaller discs).  I'll try to get a photo of that, too.  I don't recognize any other obvious crinoid parts, but last night under magnification I did discover a very small disk with a five armed star base and fanning lines similar to the more incomplete discs.  It will be tricky getting a photo of that, but I will try.

[AlexT]

Here is the primary example.  I tried to remove the matrix around it with some success.  But then, of course, I broke the fossil.  I hope this view is helpful.

[AlexT]

This is a view of what may be a stem or the only other non disc (columnal) part of a crinoid.  Much thinner than I would expect given the size of most of the columnals in the matrix.  Not sure.

[AlexT]

Then this is a picture requested by ynot (I think).

[TqB]

45 minutes ago, AlexT said:

This is a view of what may be a stem or the only other non disc (columnal) part of a crinoid.  Much thinner than I would expect given the size of most of the columnals in the matrix.  Not sure.

 

I'm sure that's crinoid. If not stem, it could be cirrus or arm.

[TqB]

Just dug this Mississippian one out of a drawer. Loads of other stuff in it but nearly all the crinoid columnals are horizontal, probably due to being smashed up in a storm

And one of them is very similar to what must have left your impressions, with a concave articulation surface.

 

(Scale bar is 1cm)

 

 

[ynot]

Yeah, I will go with everything is a crinoid (print or fossil).

Tony

[abyssunder]

As i said, no doubt about crinoid articular facets. No fossula for Enallophrentis (Heterophrentis). Thank you Tarquin for the pictures confirming crinoid.

[fifbrindacier]