Permian rugose coral faunas of Inner Mongolia–Northeast China and Japan: Paleobiogeographical implications

The faunal characteristics, successions and geographical distribution of the Permian rugose corals in Inner Mongolia–Northeast China and Japan are reviewed using current coral taxonomy and the recently revised Permian global time scale. The co-occurrences of Cathaysian compound corals, abundant non-dissepimented solitary corals, and endemic corals indicate that Inner Mongolia and Northeast China represent an independent biogeographical entity, quite separate from South China and the Japanese terranes. However, the common occurrence in South China of Permian taxa such as Wentzellophyllum, Lonsdaleiastraea, Yatsengia, Ipciphyllum, and Waagenophyllum indicates, in a broad sense, a Tethyan affinity for the Akiyoshi and Mino terranes in Japan. Rocks from the Asselian to the Artinskian in the South Kitakami Terrane of Japan contain eleven large dissepimented solitary and compound genera, including Huangia, Iranophyllum, Laophyllum, Polythecalis, Sestrophyllum, Wentzelella, Wentzellophyllum and Yatsengia. These genera are all typical of, and common in, South China, but are absent from coeval strata in Northeast China. Middle Permian rocks in the South Kitakami Terrane also contain rugose corals that are abundant in South China, in some cases the same species, such as Parawentzelella regularis, Waagenophyllum indicum, Waagenophyllum virgalense and Yatsengia kiangsuensis. Thus, the coral faunas from the South Kitakami Terrane indicate a close paleobiogeographical affinity with those from South China, which is consistent with the paleobiogeography based on ammonoids and bivalves.