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Los bosques de la Formación Guaduas (Maastrichtiano, 72-66 Ma) dan evidencia de la asociación florística y ecológica de los bosques en el trópico a finales del Cretácico. Estos bosques habitaban en zonas de tierras bajas, presentaban alta precipitación (>2000 mm anuales), abundancia y diversidad de angiospermas, y una alta intensidad de herbivoría por parte de insectos. El dosel de estos bosques era abierto, con coníferas presentes como árboles emergentes. Los helechos son abundantes en el registro polínico de final del Cretácico, pero aún se desconocen sus afinidades taxonómicas dada la escasez natural de fósiles de helechos en floras en las que predominan angiospermas. En esta ponencia se presentan cuatro especies de helechos de la flora de la Formación Guaduas representados por fósiles de frondas vegetativas y fértiles, e incluyen especies de Acrosticum (Pteridaceae), Blechnaceae, y Polypodiaceae. Dos especies son afines a Polypodiaceae: una de éstas presenta caracteres de venación que lo asocian a un clado Neotropical derivado en Polypodiaceae, mientras que la segunda especie comparte caracteres con varios linajes basales en esta familia. Estos registros indican la ocurrencia de varios linajes de Polypodiaceae en los bosques del Cretácico y contribuyen al escaso conocimiento de la flora fósil en el Neotrópico. 

The Paleocene-Eocene boundary and the early Eocene recorded the warmest temperatures of the last 60 million years. Global estimates of sea surface temperatures and many climate models have suggested a collapse of the Neotropical forests under high tropical temperatures during the early Eocene, however, the pollen record available indicates that tropical rainforests were able to persist under the increasing temperatures. Here, we test whether increased leaf evapotranspiration and consequent thermal cooling may have provided a mechanism for tropical plants to cope with increasing temperatures and avoid thermal damage to the photosynthetic machinery. We compare leaf anatomical and geochemical data from tropical plants grown under high CO2 – high temperatures at the Smithsonian Tropical Dome Project to determine whether changes in leaf evapotranspiration can be potentially observed in fossilized leaves. Results from these experiments are then compared with late Paleocene (Cerrejón Fm., 58-60 Ma) and recently discovered early Eocene (Bogotá Fm.) leaf cuticles from Colombia, as a means to assess relative changes in leaf evapotranspiration in Neotropical rainforests during the global warming events of the early Eocene. 

Context. The Southern Photometric Local Universe Survey (S-PLUS) is a project to map ~9300 sq deg of the sky using twelve bands (seven narrow and five broadbands). Observations are performed with the T80-South telescope, a robotic telescope located at the Cerro Tololo Observatory in Chile. The survey footprint consists of several large contiguous areas, including fields at high and low galactic latitudes, and towards the Magellanic Clouds. S-PLUS uses fixed exposure times to reach point source depths of about 21 mag in the 𝑔riɀ and 20 mag in theuand the narrow filters. Aims. This paper describes the S-PLUS Data Release 4 (DR4), which includes calibrated images and derived catalogues for over 3000 sq deg, covering the aforementioned area. The catalogues provide multi-band photometry performed with the toolsDoPHOTandSExtractor– point spread function (PSF) and aperture photometry, respectively. In addition to the characterization, we also present the scientific potential of the data. Methods. We use statistical tools to present and compare the photometry obtained through different methods. Overall we find good agreement between the different methods, with a slight systematic offset of 0.05 mag between ourPSFand aperture photometry. We show that the astrometry accuracy is equivalent to that obtained in previous S-PLUS data releases, even in very crowded fields where photometric extraction is challenging. The depths of main survey (MS) photometry for a minimum signal-to-noise ratioS/N= 3 reach from ~19.5 for the bluer bands to ~21.5 mag on the red. The range of magnitudes over which accuratePSFphotometry is obtained is shallower, reaching ~19 to ~20.5 mag depending on the filter. Based on these photometric data, we provide star-galaxy-quasar classification and photometric redshift for millions of objects. Results. We demonstrate the versatility of the data by presenting the results of a project to identify members of four Abell galaxy clusters in the Local Universe. The S-PLUS DR4 data allow for a reliable assessment of cluster membership out to a large radius corresponding to 5 ×r₂₀₀. The S-PLUS DR4 can be accessed through the survey data portal. All the software used to generate the catalogues for this release and the scientific investigation presented is available in the collaboration GitHub repository. Conclusions. The S-PLUS DR4 consists of a large, calibrated public dataset, providing powerful ways for studying Galactic and extra-galactic objects through an extensive set of (broad and narrow) filters.