Sosioceras is an Upper Permian shouchangoceratin pseudohaloritid characterized by a subdiscoidal shell, about 2 cm in diameter, marked by growth lines, as with Neoaganides, and having a mature peristome with a double constriction near the periphery. The suture also closely resembles that of Neoaganides. Sosioceras is found in the Upper Permian Sos...