SULCIPENTAMERUS (PENTAMERIDA, BRACHIOPODA) FROM THE LOWER SILURIAN WASHINGTON LAND GROUP, NORTH GREENLAND

Abstract

Abstract: The brachiopod Sulcipentamerus, previously considered a common endemic pentameride genus in the Lower Silurian (Aeronian) of South China, is reported from largely coeval strata in the Hauge Bjerge, Ymers Gletcher and Odins Fjord formations (Washington Land Group) of North Greenland. Two species are present. In eastern North Greenland, S. cf. dorsoplanus occurs in carbonate strata of Aeronian – early Telychian age, whereas in the western region, a new species, S. lunatus sp. nov., is described. The identification of both forms as Sulcipentamerus is indicated by their relatively long ventral median septum and dorsal inner hinge plates. The new species, Sulcipentamerus lunatus sp. nov., is characterized by a nonlobate shell, a narrow but sharply defined interarea bordering the delthyrium and a deeply concave pseudodeltidium. Despite the two known occurrences of the genus in South China and Greenland, the Sulcipentamerus‐bearing Harpidium Fauna of North Greenland (northeastern part of Laurentia) was quite distinct from both the Aeronian–Telychian brachiopod faunas of South China and the southern half of Laurentia. In general, the Aeronian pentameride brachiopod faunas of these three regions are strongly endemic, in contrast to their more tightly clustered counterparts from Avalonia, Baltica, Siberia, Kazakhstan, Tadzhikistan, Kolyma and Novaya Zemlya.