Nanshanophyllum and Shensiphyllum (Silurian Rugosa) from the Kurosegawa Terrane, Southwest Japan, and Their Paleobiogeographic Implications

摘要

Three rugose species in two genera—Nanshanophyllum hamadai n. sp., N. gokasense n. sp., and Shensiphyllum sp.—are described for the first time from the Kurosegawa Terrane, Southwest Japan. These species occur in the Middle Member of the Gionyama Formation, which is Late Llandovery to Early Ludlow (Silurian) in age. The two genera, Nanshanophyllum and Shensiphyllum, formerly were known only from South China and Qaidam. The occurrence of these two genera in Japan may indicate a paleogeographic connection between ‘Proto-Japan’ and the South China Block during the Silurian.