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
Thanks to Stefan Bengtson, for providing me with all the Machaeridia
documentation. I'm getting to know quite a bit about them and other
If you would like to study this specimen (Annette Hogström:
hint, hint...) contact Bill Heimbrock at email@example.com.
My Machaeridian References
Catalogue of the Machaeridia, Withers, Dept of Geology, British
Museum of Nat. History, 1926. Bookfinder.com
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