Permian rugose coral Thomasiphyllum as a paleogeographical indicator of the Gondwana-derived Cimmerian Continent

Abstract

• Naotic septal structure is a diagnostic character for the identification of coral genus Thomasiphyllum . • The paleogeographical location of Thomasiphyllum is constrained to the Cimmerian Continent during the Middle Permian . • Thomasiphyllum could be regarded as an index marker for paleogeographical reconstruction for the Cimmerian Continent. The genus Thomasiphyllum is a dissepimented solitary rugose coral and is characterized by the development of naotic septal structures. It has been reported throughout the Permian Period, and widely occurs in North Africa, through Central Asia to Southeast Asia, such as Tunisia, Iran, Tibet, South China, Myanmar, Thailand, and Sumatra. However, those documented Thomasiphyllum species need to be revised, because some of them lack a naotic septal structure that is a key character for the genus. In this study, the verified Thomasiphyllum occurs only within the Middle Permian carbonate strata, and geographically in Southeastern Iran, Central Tibet, West Yunnan, Central Myanmar, West Thailand, and West Sumatra. All those locations belong to a special paleogeographical region, namely the Cimmerian Continent which rifted from northern Gondwana, drifted northwards, and was located at low to middle latitudes during the Middle Permian. The genus Thomasiphyllum , therefore, is a regionally distributed taxon that is restricted to the Cimmerian Continent, which is an indicator for reconstructing the paleogeography of the blocks around the Gondwana margin during the Permian.