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Three outcrops of the Libertad and Sauces Formations from the Los Sauces area La Rioja Province, western Argentina, yielded the nine palynoassemblages studied here. Two assemblage zones are defined on the basis of the stratigraphic distribution and ranges of seventy five species of palynomorphs (42 species of spores, 32 pollen taxa and one fungus). Only thirteen species are common to both assemblages and ten species are first records for the Paganzo Basin. Assemblage 1 from the Libertad Formation is dominated by trilete spores of Cristatisporites (lycophyte) and Punctatisporites (pteridophyte). Monosaccate pollen (Coniferales/Cordaitales) is frequently present. Pteridosperms, mostly represented by Cyclogranisporites, are especially abundant in one level together with scarce striate bisaccate pollen grains. Assemblage 2 of the Sauces Formation is dominated by trilete spores related to the Pteridophyta …