Early Miocene climate estimations in Patagonia: The case of Pico Quemado, Ñirihuau Formation (Lower-Middle Miocene)

The climate during the early Neogene in Patagonia is characterized by the increase of the average temperatures until the mid-Miocene Climatic Optimum. However, the terrestrial paleoclimate of southern South America during this period is unclear. Therefore, a physiognomic analysis on the Pico Quemado (Ñirihuau Formation, lower-middle Miocene) megaflora was realized. Three types of analyses were performed: 1) Leaf Margin Analysis (LMA); 2) Leaf Area Analysis (LAA); and 3) a CLAMP analysis (Climate Leaf Analysis Multivariate Program) with two different dataset. The LMA and CLAMP predicted an estimated a Mean Annual Temperature of 10.4 ± 2.1 °C, 8.5 ± 2.1 °C and 7.2 ± 1.4 respectively. The estimations of Mean Annual Precipitation were of 123.7 ± 21.2 cm. Through the CCA, other parameters were estimated, i. e. Cold Mean Month Temperature (−3.3 ± 3.8 °C, 1.6 ± 1.6 °C); Warm Mean Month Temperature (17.4 ± 3.3 °C; 14.1 ± 1.2 °C); Mean Growing Season Precipitation (121.9 ± 42.6 cm; 78.1 ± 42.6 cm); Precipitation of the Three Consecutive Wettest Months (116.2 ± 15.3 cm; 88.5 ± 15.3 cm); and Precipitation of the Three Consecutive Driest Months (40.2 ± 19.8 cm; 54.1 ± 19.8 cm). From these results, the Pico Quemado megaflora can be characterized as having a cool temperate climate, with moderate precipitations and the development of bi-seasonality. The obtained estimations are concordant with previous morphological studies in Pico Quemado, which had proposed the same climate conditions. However, these results are inconsistent compared to other studies of early Neogene Southern Hemisphere that suggest that the climate could be warmer. This difference might be due to the few studies of climatic estimations during the early Neogene in Patagonia, precluding detailed comparisons. In conclusion, Pico Quemado paleoflora exhibits unique climatic conditions, and also floral compositions, as suggested in previous works and here corroborated. The study realized constitutes the first climatic estimations for an Argentinean megaflora developed during the Neogene.Fil: Caviglia, Nicolás Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Argentin

Revisión de la colección de hojas de angiospermas fósiles de patagonia de frenguelli (1941) con comentarios sobre las localidades originales (eoceno–mioceno)

Frenguelli describió un conjunto de hojas fósiles, recolectadas en diez localidades en el suroeste de la Patagonia, donde identificó 36 unidades taxonómicas (nueve gimnospermas y 27 angiospermas). Sin embargo, el artículo de Frenguelli presenta principalmente dos problemas: 1) la mayor parte del material no se describió ni se ilustró; 2) las localidades fosilíferas no estaban asociadas a ninguna unidad estratigráfica formal. Por lo tanto, realizamos una revisión de los afloramientos fosilíferos y de las descripciones y sistemática de los taxones de angiospermas de esta colección. Exploramos las localidades fosilíferas originales y las incluimos en tres unidades estratigráficas formales: las formaciones de Río Turbio, Río Guillermo y Río Leona. Reconocimos 27 taxones: siete fueron asignados a especies fósiles conocidas, mantuvimos 18 en nomenclatura abierta y sinonimizamos los otros dos a otro género. Proporcionamos nueva información paleoflorística a las tres unidades nombradas: en las formaciones Río Turbio y Río Guillermo el primer registro de Salicaceae (Thouinia philippii) y Grossulariaceae, Lauraceae y Salicaceae, respectivamente; y en la Formación Río Leona describimos Nothofagus variabilis y Escalloniiyphyllum sp. por primera vez.Frenguelli described a fossil leaf assemblage of 36 taxonomic units (nine gymnosperms and 27 angiosperms) collected from ten localities in southwestern Patagonia. Frenguelli’s article has two limitations according to present-day standards: 1) most of the material was neither described nor illustrated; 2) the fossiliferous localities were not associated to any formal stratigraphic unit. We revised the fossiliferous outcrops and the descriptions and systematics of the angiosperm taxa of this collection. We explored the original fossiliferous localities and we included them into three formal stratigraphic units: Río Turbio, Río Guillermo, and Río Leona formations. We recognized 27 taxa: seven were assigned to known fossil-species, we kept 18 in open nomenclature and we synonymized the other two to another genus. In addition, we reported paleofloristic information of each unit: in the Río Turbio Formation the first record of the Salicaceae (Thouinia philippii?); in the Río Guillermo Formation the first record of the Grossulariaceae, Lauraceae and Salicaceae; and in the Río Leona Formation we described Nothofagus variabilis and Escalloniiyphyllum sp. for the first time.Fil: Caviglia, Nicolás Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Pujana, Roberto Roman. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentin

Lithraea australis (Berry) comb. nov. (Anacardiaceae) from the upper section of Ñirihuau Formation (middle Miocene), Patagonia

The first records of fossil plants from the Ñirihuau Formation (middle Miocene) were published by Edward Berry at the beginning of the last century. They consist of a small collection of leaf imprints obtained from the southern margin of the Ñirihuau River valley, western Río Negro, Argentina. Based on these records, Berry described a few ferns, gymnosperms and angiosperms. Among these impressions, stand out two specimens that Berry interpreted as pinnate leaves of Cycadaceae (now Zamiaceae) that he assigned to the new species Zamia australis Berry. However, after a review of Berry's original materials of Z. australis, and new specimens collected in recent years in the same fossil locality, it is concluded that these putative zamiaceous remains are in fact angiosperm leaves. They show great similarity with those of the current South American species Lithraea molleoides (Vell.) Engl. (Anacardiaceae). To encompass these remains, a new combination, Lithraea australis (Berry) is proposed. From a paleophytogeographic point of view, the recognition of a L. molleoides closely related species suggests that the plant communities of the upper section of the Ñirihuau Formation were part of the “Transitional Province” or at least constituted the ecotone between it and the “Nothofagidites” Province.Fil: Passalia, Mauro Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina. Universidad Nacional de Río Negro; ArgentinaFil: Caviglia, Nicolás Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Vera, Ezequiel Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Geología; Argentin

The micro-and megafossil record of Nothofagaceae from South America

We compiled the numerous fossil records (486) assigned to Nothofagaceae including pollen grains (from surface sediments and continental and oceanic borehole cores), leaves, woods and reproductive structures from South America. All the records are revised and the latest systematic treatments and ages of the bearing strata of each record are followed. When possible, we proposed a subgeneric affinity to each record based on updated bibliography. Fossils of three (Nothofagus, Fuscospora and Lophozonia) of the four subgenera are found in similar proportions through time since the Late Cretaceous. Fossils with reliable affinity with subgenus Brassospora were not found in South America. Most of the records are concentrated in the southern tip of South America (Patagonia Region) and nearby areas. After a significant presence of Nothofagaceae in the Cretaceous, the family declined in diversity and abundance in the Palaeocene and then increased from the Eocene to the Miocene. In the Miocene, the records reach their maximum diversity and abundance, and Nothofagaceae usually dominate the assemblages of pollen, leaves and woods from Patagonia. Pliocene Nothofagaceae records are virtually absent, probably because sedimentary rocks of that age are rare in Patagonia. The fossil record for Nothofagaceae varies according to environmental turnover; when tropical/subtropical floras were present in Patagonia in the Palaeocene-early Eocene, Nothofagaceae contracted southwards and when open steppes developed in the Miocene of east Patagonia, Nothofagaceae contracted westward.Fil: Pujana, Roberto Roman. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Fernández, Damián Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Panti, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; ArgentinaFil: Caviglia, Nicolás Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentin