I've profiled Spinatypra from the Windom shale before but recently I found some specimens that have many more of the spines that decorated the shells intact. I was exploring a hillside exposure of the shale that my friend Mikey had led me to and I came across a total of three specimens. The shells had been compressed flat but amazingly there were spines still in place.
These are really neat specimens that help to better understand what the animal looked like. Most specimens that are found do not have the spines since they break off either prior to burial or upon extraction (mechanical or via weathering) from the rock. It's interesting that these specimens are smaller than those I've found at the Penn Dixie site. The exposure of Windom shale is also much thicker at this hillside site than what is found at Penn Dixie and 18 mile creek. The Windom shale is a member of the Moscow formation which is dated to the Givetian stage of the middle Devonian.