Wednesday, June 3, 2015

Ketternaspis (Leonaspis) williamsoni trilobite from Morocco

The spiny trilobite in today's post is Ketternaspis (Leonaspis) williamsoni from Jebel Issoumour, near Alnif, Tafilalet region, Morocco. It is a smaller species and has many spines along the length of the body starting with the genal spines and extending from the pleural lobes all the way to the pygidium. This species also has an occipital spine that extends back from the cephalon over the body but it is missing in this specimen. This is another rough specimen but I am okay with that as long as the price is reasonable. Specimens like these can be useful as examples of techniques used by preparators to replace or enhance features of a specimen. I am not saying this specimen has been faked, but there is some embellishment.
The broken occipital spine and one of the mutilated eyes are seen below.
Another preparation "mistake" is the small spines that ring the rim of the cephalon are "missing". What you see below are groves cut into the stone that look like the spines. It's a trick that some preparators use when the spines are accidentally ground away during exposure of the specimen or were not preserved well.
Because of the way the trilobite was curled in the rock, it was prepared as though in a canyon. This option reduces the amount of work needed to extract all the spines and make sure they are glued back in place.

With this view you can see that part of the cephalon test flaked off during the preparation.
Ketternaspis (Leonaspis) williamsoni comes from the Eifelian stage of the Devonian.

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