Patterns of Change 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 inhabited 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 dominated by porous Sphaerellaria, to shallower shelf environments, in which spongy-lattice Spumellaria prevailed.