Taxonomical Diversity and Morphology of Rostroconch Shells of the Family Arceodomidae fam. nov. from the Early Permian Shakhtau Reef Massif (Mollusca; Southern Cis-Urals)

Three species of the genus Arceodomus ( A. praepermica (Fredericks, 1915), A. colvae (Fredericks, 1915), and A. fredericksi sp. nov.) described from the Asselian and Sakmarian carbonates of the Shakhtau reef massif (Southern Cis-Urals). The architecture of complex, at least two-layered shells is discussed in detailed and refined and their functional morphology is analyzed. Muscle scars of Arceodomus are described and their interpretation are proposed. A new family Arceodomidae fam. nov. is proposed in the order Conocardiida for the placement of the genus Arceodomus based on the combination of several morphological characters.