A tentative framework of ten echinoderm zonules, some of which are not new, is proposed: Nortonechinus owensis Zonule (upper Owen Member, Lime Creek Formation): Dactylocrinus Zonule (upper Cerro Gordo Member), Xenocidaris Zonule (lower Cerro Gordo Member, Lime Creek Formation); Desmidocrinus Zonule, Belanskicrinus Zonule, Agelacrinites Zonule (Mason City Member, Shell Rock Formation); Strobilocystites Zonule, Euryocrinus Zonule (upper Rapid Member), Hexacrinites Zonule (middle Rapid Member), Megistocrinus clarki Zonule (lower Rapid Member, Cedar Valley Formation). Some forms, or assemblages, appear to have decided stratigraphic significance, but more study is needed.
Proceedings of the Iowa Academy of Science
©1970 Iowa Academy of Science, Inc.
Strimple, Harrell L.
"Echinoderm Zonules in the Devonian of Iowa,"
Proceedings of the Iowa Academy of Science, 77(1), 249-256.
Available at: https://scholarworks.uni.edu/pias/vol77/iss1/37