Occurrence of the isopod Archaeoniscus coreaensis new species from the Lower Cretaceous Jinju Formation, Korea

The fossil isopod crustacean genus Archaeoniscus has been known to occur in England, France and Germany during the Upper Jurassic, and in Mexico and Egypt during the Lower Cretaceous. The morphology of this genus is unique in having dorsoventrally compressed body, the cephalon set deeply into the first pereionite, pleon as wide as pereion, and a broad semicircular pleotelson. These features have resulted in placing the classification of the genus in the monotypic family Archaeoniscidae. However, due to the lack of detailed morphological data, suprafamilial classification of this genus has remained unclear, as well as its ecology and lifestyle. Here we report Archaeoniscus coreaensis n. sp. from the Jinju Formation, Gyeongsang Basin, Korea. The occurrence of Archaeoniscus in the East Asia implies that the genus may have had a worldwide distribution. The Gyeongsang Basin was a Cretaceous backarc basin, which consists of exclusively non-marine sedimentary sequences. The occurrence of this ...