The first Middle Ordovician and Gondwanan record of the cincinnaticrinid crinoidOhiocrinus byeongseonin. sp. from South Korea: biostratigraphy, paleobiogeography, and taphonomy

Abstract

AbstractOhiocrinus byeongseonin. sp. from the Middle Ordovician (Darriwilian) Jigunsan Formation of South Korea in the Sino-Korean (North China) block is the oldest species ofOhiocrinusof the Cincinnaticrinidae and the first record outside Laurentia.O.byeongseoniis 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 ofO.byeongseonipresents a considerable spatiotemporal gap and ecologic disparity in evolution ofOhiocrinusand the Cincinnaticrinidae.UUID:http://zoobank.org/240417a4-8d33-4f45-aedb-afcc07f1ecbb