Pentececrinus, a new microcrinoid from the Louisiana Formation of Missouri

A new microcrinoid, Pentececrinus parvus (sub-order Cyathocrinoidea), from the Louisiana formation (Devonian-Mississippian) of Missouri is described and compared with other nonbrachiate crinoids possessing only three circlets of plates (IBB, BB, OO) and an anal. Such crinoids have been reported from the Mississippian, Pennsylvanian, and Permian of the United States, the lower Carboniferous of Europe, and the Permian of Timor and Russia. With the addition of Pentececrinus, it is inferred that they form a phyletic group extending from late Devonian or early Mississippian to Permian time and that known Permian representatives do not indicate regressive evolution or aberrant specialization.