A succession of characteristic radiolarian assemblages has been recognized through the Late Carboniferous and stratotypic Permian of the Urals and west Texas. The majority of the component taxa are yet undescribed. The oldest well-preserved assemblage from the regions appears in the lower Gzhelian Stage of the Urals and consists of more than 30 species belonging to 12 genera. Typical are large Albaillella, curled Haplodiacanthus, abundant spongy, cross-axon forms with an open central area, and Polyentactinia of octahedral form. The top of the Gzhelian Stage contains 54 species assigned to 18 genera. A new genus of the Corythoecidae, species of a highly plastic, closed spongy, cross-axon form, an unsegmented Albaillella with massive basal spines, Camptoalatus, Popofskyellu , and various triradiate, cross-axon forms are characteristic.

The lower horizons of the Asselian Stage are distinguished by the appearance of Latenofistula crucex, a unique, large-pored Entactinosphaera, and spherical and elliptical forms with multiple concentric shells. Thus, radiolarian assemblages gradually change at the Carboniferous-Permian boundary. The Sarabil Suite of the Sakmarian Stage is distinguished by Haplodiacanthus perforatus (Kozur), Albaillella permica (Kozur), and large Helioentactinia. In the upper part of the Sakmarian Stage appears as assemblage of Camptoalatus monopterygius Nazarov and Rudenko, Raphidociclicus hiulcus Nazarov and Rudenko, and a new species of Ruzhencevispongus. The base of the Artinian Stage is characterized by the appearance of a new, multishelled, spongy polycystine genus possessing a three-rayed interna framework, Tormentum? pavlovi (Kozur), and a large, triradiate form with two strongly curving legs. The lower and middle parts of the Aktastinian Substage (Artinian Stage) are distinguished by an undescribed, small, discoidal, five-rayed radiolarian and by Entactinosphaera sp. The top of the Artinian Stage is typified by Haplodiacanthus anfractus, Raphidociclicus gemellus, and Ruzhencevispongus uralicus Kozur, and marks the first appearance of Follicucullus Ormiston and Babcock in the Urals. This is clearly an older horizon than that of the type species, Follicucullus ventricosus, known from the Guadalupian of west Texas. Direct comparison of radiolarian faunas indicates a correlation of the Bone Spring Limestone (Leonardian) of west Texas with the upper Sakmarian and/or Artinian Stages of the Urals.

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