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Six angiosperm pollen types studied with SEM are recorded in the Cretaceous (early Aptian) Ticö flora on the basis of material recovered from two localities: Anfiteatro de Tico and Bajo Tigre. Clavatipollenites dominates, with four types described. The other two types, based on single specimens, were referred to Retimonocolpites and to the Anacostia type. Comparisons are made with similar species found in other Cretaceous paleofloristic regions and with other Aptian pollen assemblages from Patagonia. The chlorantha-ceous affinity of Clavatipollenites agrees with known paleobotanical, sedimentological, and paleoclimatical data obtained for the same fossiliferous horizons of the Anfiteatro de Ticö Formation studied here. During the early Aptian, a warm and humid paleoclimatic belt extended to latitudes greater than 60°S in SW Gondwana. This belt is known to have persisted until the late Aptian in southern Patagonia. The angiosperm pollen variety is further underscored by fossil leaves found in two of the horizons studied here, suggesting that angiosperms may have existed during the Barremian in SW Gondwana (Patagonian Province). [ABSTRACT FROM AUTHOR]

The subcosmopolitan and aquatic monocot family Potamogetonaceae Berch. and J. Presl 1823 comprises extant and fossil genera. Its known fossil record is composed mainly of fruit remains, and it comes only from Eocene to Pliocene sediments of the Northern Hemisphere (Europe, Saudi Arabia, and China). Recently, several fruits sharing characters with living and fossil Potamogetonaceae genera have been found within the Paleogene Baibián Beds, Chubut, Patagonia, Argentina. Fossils were collected at the Puesto Baibián locality, which outcrops at the eastern sector of the Sierra de La Colonia. Fossils are impressions/compressions of infructescences and isolated fruits and seeds preserved as molds and casts. The infructescences are probably racemes bearing fruits placed most likely in whorls of four each. Isolated fruits are small one-seeded bisymmetrical endocarps. Palynological studies of the beds show the presence of an assemblage similar to those found in sediments of the Northern Hemisphere where Potamogetonaceae fossil fruits were previously recorded. This report constitutes the first fossil record of Potamogetonaceae for the Southern Hemisphere. [ABSTRACT FROM AUTHOR]