Edgardo J. Romero

Casuarinaceae from the Eocene of Patagonia, Argentina

Casuarinaceae, today restricted to the Australasian region, has an extensive fossil record. In this article, we evaluate previous records and recent findings from Patagonia, where Casuarinaceae are known from the Tufolitas Laguna del Hunco (early Eocene) in northwestern Chubut, Argentina. Based on characters found in numerous branchlets, infructescences, and male inflorescences with pollen of the Haloragacidites harrisii type, the presence of three fossil species within the genus Gymnostoma is confirmed: G. patagonicum comb. nov., G. archangelskyi sp. nov., and G. argentinum sp. nov. This is the oldest worldwide report of male inflorescences and the first record of vegetative branchlets and male inflorescences for South America. These fossils are of particular interest because Casuarinaceae is now extinct in South America, and they support the view that the family was diverse and had widespread distribution during the early Eocene climatic optimum. The diverse Gymnostoma described here further strengthens biogeographic links between Paleogene floras of Patagonia and Australasia.

Airborne pollen and spores monitoring in Buenos Aires City: a preliminary report. Part I. Trees and shrubs (AP)

SummaryThe monthly trees and shrubs pollen (AP) content of the atmosphere during a whole annual period is analyzed. Thirty airborne pollen types have been identified. Most of them come from cultivated plants flowering in late winter-early spring. Thereby the annual peak is recorded in October. The highest frequencies recorded are those ofFraxinus americana, Acer negundo, Platanus spp. andMorus nigra. A second minor peak is recorded in March, and is mainly due toCasuarina spp./Myrica spp. pollen. Aeropalynological data are discussed and correlated with phytogeographical, phenological and meteorological parameters.

A new early angiosperm leaf from the Anfiteatro de Ticó Formation (Aptian), Santa Cruz Province, Argentina

A new record of angiosperm from Aptian deposits of the Anfiteatro de Tico Formation (basal unit of the Baquero Group), in its type locality, north-center of Santa Cruz province, Argentina is reported. This record integrates the fossiliferous level Williamsonia-Zamites that contains abundant remains of bennettite leaves and was deposited in floodplain facies. The fossil consists of a single leaf imprint, with entire margin and festooned brochidodromous venation of low rank. It has features that define, in part, the nymphaeaphyll morphological type. This type occurs among the most early assemblages having angiosperms (northeastern Brazil, Portugal, South Australia, eastern North America), and is part of a physiognomic-foliar pool associated to taxa considered to be basal within the group. This foliar morphotype, is found in some members of extant angiosperms of usually herbaceous habit, and perhaps, by analogy, this may have been the original habit of our fossil species. The mega floristic record of eocretaceous angiosperms from Southern Hemisphere is scarce. In spite of them, angiosperm foliar remains from other location (Bajo Tigre) of the Anfiteatro de Tico Formation are known. They are different to this new record. This incipient diversity suggests an even (pre-Aptian) presence of the angiosperms in the region.

Airborne pollen and spores monitoring in Buenos Aires city: A preliminary report. Part II. Herbs, weeds (NAP) and spores. General discussion

SummaryThe herds and weeds pollen (NAP) and spores of Buenos Aires city were collected using a Tauber trap from July 1989 to June 1990. A high NAP pollen production period was found from October to March, reaching an annual peak in October. The NAP fraction is dominated by Compositae, Poaceae, Cyperaceae and Chenopodiaceae/Amaranthoideae. Spores are scarce along the year and they are mainly represented by Bryophytes. From the comparison of trees and shrubs pollen content (AP), NAP and Spores fractions, three aeropalynological seasons could be described: An AP Season with dominance of trees and shrubs, from July to October; a NAP Season with dominance of herbs and weeds, from November to April, and a Spore Season from May to June.

Flora Gimnospérmica de la Formación Ñirihuau (Oligoceno Tardío-Mioceno Temprano), Provincia de Río Negro, Argentina

Abstract. GYMNOSPERM FLORA FROM THE ÑIRIHUAU FORMATION (LATE OLIGOCENE-EARLY MIOCENE), RÍO NEGRO PROVINCE, ARGENTINA. The Cenozoic paleofloras in the area of San Carlos de Bariloche, Argentina are located mainly along the Ñirihuau and Pichileufú rivers, and belong to several stratigraphic units. Of these, the flora of Pico Quemado is situated in the most basal part of the Ñirihuau Formation and is probably late Oligocene-early Miocene in age. It is described herein, gymnospermous foliar impressions and compressions of Araucaria nathorstii Dusén (section Araucaria) and an ovuliferous scale of Araucariaceae; the latter constitutes the first evidence of reproductive structures belonging to section Araucaria for the Cenozoic of South America. Foliar impressions and compressions of Podocarpaceae are also present. Among them, the presence of podocarps with bilateral leaves related to Dacrycarpus de Laubenfels, previously known from Eocene outcrops of Chile, Argentina and Antarctica, allows extending their record up to the late Oligocene-early Miocene of Patagonia and relating them with the fossil and extant floras from the Australasian region. The morphology of the studied leaves, as well as their affinities with extant forms, together with the sedimentology, palynology, angiospermous megaflora and presence of freshwater bivalvia, allow suggesting a fluvial-shallow lacustrine depositional setting, developed under temperate to warm-temperate and humid climate.

Improntas foliares de la formación La Ollita (Mioceno), Valle del Cura, Cordillera frontal, provincia de San Juan, Argentina

Leaf imprints from the La Ollita Formation (Miocene), Valle del Cura, Cordillera Frontal, San Juan province, Argentina. A monospecific collection of leaf imprints is described. This set belongs to one freshwater angiosperm species corresponding to the Hydrocharitaceae, so that this family must have formed part of the aquatic vegetation in water bodies probably entailing the Paranense sea.