Paleonet: fossil ID help

Yancey, Thomas E yancey at
Fri Feb 20 20:16:00 UTC 2015


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<mailto: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<mailto:stjohn.2 at>

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