Oepikina minnesotensis

Found in both Decorah and Platteville Formation. One of two official Oepikina species found in Decorah and Platteville Formation. #1 shows a distinct feature of Oepikina that most sources doesn't seem to mention that makes it distinct from rest of family branch at least for Decorah/platteville formation - A distinct growth line that always occurs 80% to 90% of the distance from hinge teeth. #2 shows that compare to most if not all brachiopods from Decorah to Platteville Formation, Oepikina is the most extreme in inflated shells, often resembles a cannon ball cut into two dues to its fine costae lines making it looks nearly black in Decorah formation. #3 So far I have only specimens from Platteville formation that shows muscle structures. The lighter colors shows where the muscles are attached to the shell and the darker colors represent the prominent central septae that runs down the middle of O. minnesotensis. It lacks the irregular septae that radiates away from the hinge teeth of some O. inquassa individuals.