Tagenocrinus and Lecocrinus Two New Flexible Crinoid Genera from the Silurian and Devonian of North America

Tagenocrinus conradae n.gen., n.sp., is the first species of the flexible crinoid family Nipterocrinidae to be described from the Middle Devonian (Givetian). Tagenocrinus is characterized by a low bowl-shaped cup and a pentagonal radianal that contacts the infrabasal circlet. The establishment of Tagenocrinus prompted a review of the nipterocrinids and as a consequence three species with low broad cups and two or more primibrachs previously assigned to Pycnosaccus have been reassigned to the new genus Lecocrinus, which ranges from the Upper Silurian (Wenlockian) to the Upper Devonian (Frasnian).