Paleonet: fossil ID help

friedmanhvj at friedmanhvj at
Sun Feb 22 23:01:05 UTC 2015

the first set of pictures, I could only guess that it  is a section of an organism belonging  to the Phylum Cnidaria.The second set is more unambiguos: Phylum Porifera, the structures shown  are sponge spicules.  The structure to which they seem to be attached, it is probably not their natural setting, but rather it is an articifical conglomeration of the spicules. (Some kind of taphonomic process could have been  at  work  i.e. algal  or microbial mat that upon disaggregation of the spicues, consolidated the whole structure and later was fossilized as such).

Virginia FriedmanPaleontologistChildren's  Natural History Museum Fremont, CA. 

     On Friday, February 20, 2015 2:16 PM, "Yancey, Thomas E" <yancey at> wrote:

Fascinating fossils and ones I've not seen before, despite many years of looking at Penn fossils. To start with, the two isolated spicules are certainly sponge spicules of the polyaxon type. Not uncommon, but stouter then most and with some knob on the end. The knob is part of the outer surface of a sponge pavement.
The asterism type features adhering to the clast may well be sponge spicules, but it is unusual to see them fused to a matrix. A real mystery.
The other masses are clearly basal secretions of an animal, but it is a type I've never encountered. The one most like a disk shows a definite attachment area in the smoothest crescent part. The others also appear to be similar. The part that detached from the base is likely to be a soft tissue organism. My best guess is that it is an attachment base for a cnidarian polyp. Large ones can move around and if there was one that was secreting a basal platform while it was shifting position, that would produce such a structure. This may be a first - a previously unrecognized form of fossil. To test this idea, consult a specialist in modern polyps and see if something like this has been observed in living forms. 
Very impressive.
Tom Yancey
Thomas E Yancey
Dept. of Geology and Geophysics
Texas A&M University
College Station, TX 77843-3115
email: tyancey at
Voice: 979-845-0643
Fax: 979-845-6162

On Feb 16, 2015, at 12:42 PM, Stjohn, James wrote:

If anyone is familiar with the Pennsylvanian, a student of mine and I would like some help in identifying a few fossils from the Poverty Run Limestone and Boggs Limestone of eastern Ohio.
Along with captions, photos are posted at:
James St. John (Geology, Ohio State University at Newark)
stjohn.2 at

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