Patterns of Changes in Radiolarian Associations in the Early Tournaisian (Mississippian) and Kungurian (Cisuralian) in Eastern European Russia

There are important morphological differences between the dominant higher taxa (classes) in associations of radiolarians that lived at different depths of paleobasins. A similar inversion of dominant radiolarian taxa can be seen in the Early Tournaisian (Mississippian) and the Kungurian (Cisuralian) and may indicate a change in their habitat from deeper conditions where porous Sphaerellaria dominant, to less deep-water shelf environments, in which spongy-lattice Spumellaria prevailed.