Recovery of Laurentian cyclocystoids following Late Ordovician extinctions (Brassfield Formation, Llandovery; southwestern Ohio)

Abstract

Zygocycloides? foerstei n. sp. is described from the Llandovery (Aeronian) Brassfield Formation of southwestern Ohio. This is among the oldest reported Silurian cyclocystoids from North America and is the only North American Llandovery cyclocystoid that is preserved with a complete rim of marginal ossicles. Zygocycloides Smith and Paul, 1982 is most similar to Nicholsodiscus Glass et al., 2003 (Katian) and Perforocycloides Ewin et al., 2019 (Llandovery, Telychian), both from Anticosti Island, Québec. Cyclocystoids (Ordovician to Mississippian) survived Late Ordovician extinctions, and this discovery documents that this echinoderm clade was part of shallow-water, marine paleocommunities during the initial post-extinction transgression onto the Laurentian platform. UUID: http://zoobank.org/3d3e092e-267b-4841-9245-6275d1eb79a1

New specimens of Cyclocystoides scammaphoris (Echinodermata) from the Upper Ordovician rocks of the American midcontinent with implications for cyclocystoid functional morphology

“…These authors also provide a historical summary of early cyclocystoid investigations, including those by Salter and Billings (1858), Hall (1872), Bather (1900), Raymond (1913), Begg (1934Begg ( , 1939, Sieverts-Doreck (1951), Kesling (1963Kesling ( , 1966, and Nichols (1969Nichols ( , 1972. Subsequent investigations have focused largely on cyclocystoid occurrences and diversity of cyclocystoids (Berg-Madsen, 1987;Haude and Thomas, 1994;Smith and Wilson, 1995;Glass et al, 2003;Reich and Kutscher, 2010;Sprinkle et al, 2015;Reich et al, 2017;Ewin et al, 2019;Müller and Hahn, 2019;and Ausich and Zehler, 2022). Skeletal homologies, functional morphology, and life mode are poorly understood because cyclocystoids are rare as fossils and microscopic details of their skeletons generally are not well preserved.…”