Recent studies of Ancistrospora and Potonieisporites palynozones in the Paganzo Basin (Argentina) have shown that they belong to a single biostratigraphic unit for which the name Raistrickia-Plicatipollenites subzone has been proposed. This unit has been referred to the Potonieisporites-Lundbladispora zone from the Chacoparaná Basin as a lower subzone; the upper subzone would then be an Interval sub-zone. On the other hand, recent studies in Brazil have shown that a new pollen association can be defined beneath the basal G-H1 zone; it has been compared with the Paganzo association on the basis of common taxa. This similarity is now strengthened by the new findings in Argentina, and the pre-G-H1 interval probably can be correlate d with the Raistrickia-Plicatipollenites subzone. It thus seems that floras from both áreas had common, basic components and that variations between them were controlled by paleogeography, paleoclimate and paleoenvironment.
