New endemic brachiopod and echinoderm genera from the Upper Ordovician of the St. Petersburg region, northwestern Russia

摘要

A new brachiopod and a rhombiferan cystoid are described from the Gryazno and Schundorovo formations (Upper Ordovician; middle Sandbian), Idavere Regional Stage, of the St. Petersburg Region (northwestern Russia). The fossils are part of an abundant, well-preserved benthic fauna. The rhynchonelliformean brachiopod Madiorthis alsami gen. et sp. nov. belongs to the family Plaesiomyidae (subfamily Plaesiomyinae); the dichoporite echinoderm Fusicystis magnificus gen. et sp. nov. is assigned to the family Echinoencrinitidae (subfamily Scoliocystinae). These new taxa have not been found outside the type locality.