Bill Heimbrock

Machaeridian!: Lepidocoleus jamesi

Genus/species: Lepidocoleus jamesi
Family/subfamily: Cirripedia/Machaeridia
Phylum: Problematica.
Period: Late Ordovician Period
Formation: Middle Arnheim Formation
Locality: Florence, KY "Cyclora Hash Field" 

I found a Machaeridian body in a layer of Zygospira on the Florence Arnheim site. The spot was between the two fossil hash layers. Unfortunately, I found them after bathing the shale in Vinegar for 24 hours. I was looking for my mystery plates. This, I believe, destroyed the plates, but left the body and a portion of the plates.

This is my first attempt at scanning the Machaeridian. I used a 10X magnification. 30X could not get it all in the picture. I know the pictures are not great. There are two fragments. I show four views of each fragment. The sketch I have included is from "Catalogue of the Machaeridia", Withers, 1926. It shows the profile of Lepidocoleus ulrichi. My specimen is probably Lepidocoleus jamesi, known from the Cincinnatian.

L. jamesi is said to attain a length of 12 mm with "probably" 15 plates in a column; width equal to the height of the exposed surface of 3 plates. (According to "Catalogue" page 13.) My two fragments are each 6 mm long. the straight piece having 9 and a half plates and the bent fragment having 3 plates in the column and 5 plates in the bend. My specimen is probably nearly complete. Both fragments were found in one scoop of clay. I could see that there was a bad fracture in the straight piece and right after I imaged them and put them back in the bag, the straight piece broke. At least I've got both pieces. That might not have found the other piece if it had broken before I found it among the Zygospira.

Thanks to Stefan Bengtson, for providing me with all the Machaeridia documentation. I'm getting to know quite a bit about them and other problematica.

If you would like to study this specimen (Annette Hogström: hint, hint...) contact Bill Heimbrock at

My Machaeridian References

Catalogue of the Machaeridia, Withers, Dept of Geology, British Museum of Nat. History, 1926. COPIES AVAILABLE!

The Machaeridia - A Square Peg in a Pentagonal Hole, Bengtson, S. 1978, Thalassia Jugoslavica 12, 1-10. (I had to buy my copy from Dr. Stephan Bengtson at the Swedish Museum)

Aspects of Problematic Fossils in the Early Palaeozoic, Bengtson, S, 1977, Uppsala (Dr. Bengston gave me a copy with his compliments)

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