by Ron Fine

Note from Webmaster: This page is also an offer from an amateur Paleontologist (Ron Fine) to allow the use of his specimens in professional research. This type of amateur/professional interaction has been a big boost to Paleontology and is encouraged by the Dry Dredgers. Send inquiries directly to Ron at  fossilboy@hotmail.com

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Philhedra laelia (Hall) is an inarticulate brachiopod from the Richmondian portion of the Cincinnatian series of the Ordovician. It can be found on hard surfaces, especially other brachiopods, in protected nooks and crannies. I have collected over fifty specimens of this tiny brachiopod and began to notice differences in some of the shells that leads me to believe there may be a second species in our area. I am looking for an interested professional to explore this possibility and publish on it if proven true.

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Philhedra on brachial valve of Rafinesquina. 
All photos courtesy of Bill Heimbrock

These two Philhedra (below) are pretty typical, a conical shell, tall relative to the width, with many fine ribs radiating from the apex and terminating as spines along the entire margin. In particular, note that the spines at the rear end (see arrows) are the same thickness and length as all the others. They can be found on almost any hard surface, regardless of roughness. I have found them in the Richmondian of Ohio and Indiana.

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Mystery Philhedra with Petrocrania on brachial valve of Rafinesquina. 

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This is what I believe may be a second species (pictured below and above). About twenty percent of my specimens have a low conical shell, relative to the height. The ribs are fewer in number and thicker than the common variety. Of special note (see arrows) are the spines at the rear end, which are shorter than the rest and thinner. These characteristics hold regardless of size. I have only found the mystery Philhedra on smooth surfaces, which I presume is because the internal tissue couldn’t function well on rough surfaces due to being flatter than the regular variety. I have only found them at sites in Indiana.

Close-up of above Mystery Philhedra

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In addition to the mystery Philhedra I have also found two specimens from non-Richmondian sites in Ohio. Specimen A is from a Fairview formation site in Fairfield. I have no reason to believe this is not P. laelia. Specimen B is from Trammel Fossil Park, likely the Bellvue formation. It contains several juvenile Philhedra on a bryozoan. These look somewhat peculiar to me, but I have never seen baby Philhedra before, so these may not be anything unusual. 

Both specimens are available, along with all others in my possession, for study. Any interested parties can reach me at fossilboy@hotmail.com

Photos by Bill Heimbrock
Descriptions courtesy of Ron Fine
Web page development by Bill Heimbrock

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