Ohiocrinus byeongseoni n. sp. from the Middle Ordovician (Darriwilian) Jigunsan Formation of South Korea in the Sino-Korean (North China) block is the oldest species of Ohiocrinus of the Cincinnaticrinidae and the first record outside Laurentia. O. byeongseoni is characterized by a loosely clockwise-coiled anal sac, isotomous branching throughout arms, long, slender xenomorphic column, and small lichenocrinid-type holdfast. The new species occurs in association with a deep-water siliciclastic environment, unlike the Laurentian species with a shallow-water carbonate environment. The monospecific crinoid assemblage is interpreted as parautochthonous, considering that the crinoids were reworked by relatively weak down-current probably caused by storm but preserved within the environment where they lived. The occurrence of O. byeongseoni presents a considerable spatiotemporal gap and ecologic disparity in evolution of Ohiocrinus and the Cincinnaticrinidae.
UUID: http://zoobank.org/240417a4-8d33-4f45-aedb-afcc07f1ecbb
Goryeocrinus pentagrammos n. gen. n. sp. from the Jigunsan Formation of South Korea is described and is the first diplobathrid recorded from Middle Ordovician (middle Darriwilian) strata of East Gondwana. Phylogenetic analyses suggest that G. pentagrammos n. gen. n. sp. is a member of the paraphyletic Rhodocrinitidae of the Diplobathrida and most closely related to Paradiabolocrinus from the Late Ordovician (Sandbian) of Laurentia. Goryeocrinus pentagrammos n. gen. n. sp. is characterized by having a pentameral, flat bowl-shaped calyx, a conspicuous pentagrammatic ridge formed by bifurcated median ray ridge and pentagonal basal ridge, at least two interradials in the first row of regular interrays, an anitaxial ridge originating from the CD interray but close to the C ray radial, and lacking intrabrachials and interradials between secundibrachials. The occurrence of G. pentagrammos n. gen. n. sp. from South Korea (East Gondwana) drastically expands the Ordovician paleogeographic range of camerates, which otherwise have been recorded from Laurentia, West Gondwana, Avalonia, and Baltica.
UUID: http://zoobank.org/a5f8fc12-25a5-4e7c-92e8-bf3ea07c3ba3
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