One of the spinier trilobites that can be found in the Bois D'Arc formation is Kettneraspis sp. it is usually a small fossil and it is best if you find it just peeking out from the rock. I found two nearly complete specimens while searching last August and some disarticulated pieces as well.
This is the first articulated specimen. It is about 75% there but the delicate spines are all weathered away and the left free cheek of the cephalon is missing. It's not bad for a surface find as most of the really nice prepped specimens are found by splitting the rock and looking for the outline.
Here is an isolated free cheek which shows the short spines that are on the lateral border of the cephalon.
I did find one really nice specimen but the rock it was on was very fractured and I didn't think I would be able to either get it home without further damage or repair it. Lucky for me Leon took a look at it and thought it could be saved. He wrapped it up in aluminum foil and took it back with him. A few weeks later he messaged me and told me that he'd been able to save it and it turned out to be a pretty nice specimen. Some of the spines are broken or missing and the cephalon has been compressed but it appears to be 95% complete.
The most common species found is Kettneraspis williamsi but Leon told me that my fossil was an undescribed species. That may be because the specimen was incomplete or warped such that ID was difficult.
I found the specimens shown on this page in the Bois d'Arc formation (Cravatt member) near Clarita, OK which is Devonian in age (Lockhovian stage). The Bois d'Arc and Haragan formations interfinger with each other and are roughly the same age (Devonian, Lockhovian stage). They are both roughly correlative to the Helderberg fauna of New York and thus are contemporaneous with the Coyemans, Kalkberg and New Scotland formations.