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The upper Palaeozoic basins of central-western Argentina include continuous fossiliferous successions spanning the Carboniferous-Permian interval. The palynostratigraphic biozones comprise Late Mississippian, Pennsylvanian and Cisuralian assemblages. Recently, new palynofloras of the La Veteada Formation were referred to the Lopingian (late Permian). However, they are characterized by spores and tetrads of Lundbladispora spp. and Densoisporites spp., pollen grains of Lunatisporites pellucidus, L. noviaulensis and Protohaploxypinus samoilovichii, and the alga Syndesmorion stellatum, that distinguish the post-Permian recovery floras worldwide. A new uranium-lead chemical abrasion-isotope dilution-thermal ionization mass spectrometry (U-Pb CA-ID-TIMS) age confirms the Olenekian age of this stratigraphic unit and allows the identification of the first Early Triassic palynofloras in this region of western Gondwana. Comparison and correlation with similar assemblages from the southern and northern hemispheres supports the Early Triassic turnover with an increase of lycopsid cavate spores associated with some diagnostic species of taeniate and non-taeniate bisaccate pollen. [ABSTRACT FROM AUTHOR]

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Palynology is one of the most useful tools for constructing biostratigraphic charts in the late Paleozoic basins of South America, but the lack of radiometric ages often makes it difficult to establish the precise age of the biozones. This paper focuses on two points: (i) the description of new Argentinian palynological assemblages referred to the Lueckisporites/Weylandites (LW) Biozone and (ii) the application of a new isotopic age that enables more confident large-scale correlations with the neighboring Paraná Basin of Brazil. The palynofloras were recovered from the upper part of the De La Cuesta Formation that crops out in the retroarc basin of the Paganzo Basin, more specifically obtained from mudstones intercalated with limestones, cherts, and tuffs interpreted as being deposited in a shallow water body. The assemblages are characterized by an abundance of bi-taeniate pollen grains of the Lueckisporites complex and multitaeniate pollen grains such as Lunatisporites, Protohaploxypinus, Striatopodocarpidites, Tornopollenites, and Vittatina. Colpate pollen grains are also represented by Marsupipollenites and Pakhapites. A U-Pb CA-ID-TIMS age of 278.84 ± 0.22 Ma, obtained from a tuff level interstratified with the fossiliferous strata, allows the age of the LW Biozone in the Paganzo Basin to be constrained for the first time and the adjustment of the record Lueckisporites virkkiae in Gondwana. Moreover, this date enables precise correlations with other basins, such as the San Rafael Basin (Yacimiento Los Reyunos Formation) in Argentina and the Brazilian Paraná Basin (Iratí Formation). [ABSTRACT FROM AUTHOR]

The Carrizal Formation, exposed in the Marayes-El Carrizal Basin (western Argentina), has been the focus of palaeobotanical studies since the late 1800s. The recent finding of well-preserved palynological assemblages provides the first detailed studies about its palynofloras. In this paper, the 63 taxa identified in the unit are illustrated and discussed, as well as their stratigraphic distribution in equivalent palynological assemblages of Argentina. Some spore species are revised: Uvaesporites hammenii (Herbst) Césari, comb. nov., Retusotriletes wielandii (Jain) Césari, comb. nov. and Lundbladispora stellae (Herbst) Césari, comb. nov. The recognition of Cadargasporites baculatus de Jersey & Paten emend. Reiser & Williams, Craterisporites rotundus de Jersey, Enzonalasporites vigens Leschik, Leptolepidites argenteaeformis (Bolkhovitina) Morbey, Protodiploxypinus americus Dunay & Fisher and Rugulatisporites permixtus Playford, among others, appears to be useful for local and intercontinental correlations. A Carnian age is proposed for the palynofloras. [ABSTRACT FROM AUTHOR]

A new monosulcate species, Shanbeipollenites lagarcitensis sp. nov. is described from the Lower Cretaceous Lagarcito Formation, Sierras de Guayaguas (north-western San Luis Basin), Argentina. Shanbeipollenites lagarcitensis shares with other species of this genus a broadly ellipsoidal outline and a diagonally disposed distal sulcus. However, the new species differs from the psilate type species Shanbeipollenites quadrangulatus and from S. quadratus by the presence of sculptural elements distributed at the equatorial region, close to the opposite ends of the sulcus. The thicker wall, exine separation, much more strongly diagonal offset of the sulcus and the rugulate-verrucate sculpture with an equatorial distribution close to the opposite ends of the sulcus, distinguish this new species and expands the concept of the genus Shanbeipollenites. The presence of two separate exine layers supports its gymnosperm affinity. Furthermore, the occurrence of Shanbeipollenites lagarcitensis in the Albian Lagarcito Formation from mid–latitudes, central–western Argentina constitutes the youngest record of the genus worldwide. This new record expands the biostratigraphical range of the taxon into the Albian. [ABSTRACT FROM AUTHOR]

Summary: The pinnately lobed Aptian leaf fossil Mesodescolea plicata was originally described as a cycad, but new evidence from cuticle structure suggests that it is an angiosperm. Here we document the morphology and cuticle anatomy of Mesodescolea and explore its significance for early angiosperm evolution.We observed macrofossils and cuticles of Mesodescolea with light, scanning electron and transmission electron microscopy, and used phylogenetic methods to test its relationships among extant angiosperms.Mesodescolea has chloranthoid teeth and tertiary veins forming elongate areoles. Its cuticular morphology and ultrastructure reject cycadalean affinities, whereas its guard cell shape and stomatal ledges are angiospermous. It shares variable stomatal complexes and epidermal oil cells with angiosperm leaves from the lower Potomac Group. Phylogenetic analyses and hypothesis testing support its placement within the basal ANITA grade, most likely in Austrobaileyales, but it diverges markedly in leaf form and venation.Although many Early Cretaceous angiosperms fall within the morphological range of extant taxa, Mesodescolea reveals unexpected early morphological and ecophysiological trends. Its similarity to other Early Cretaceous lobate leaves, many identified previously as eudicots but in some cases pre‐dating the appearance of tricolpate pollen, may indicate that Mesodescolea is part of a larger extinct lineage of angiosperms. [ABSTRACT FROM AUTHOR]

Premise: The sooty molds are a globally distributed ecological group of ascomycetes with epiphyllous, saprotrophic habit, comprising several phylogenetically distant taxa (i.e., members of the classes Dothideomycetes and Eurotiomycetes). Their fossil record extends almost continuously back to the early Cretaceous; however, they are hypothesized to have originated in the early Mesozoic. Here, we describe new specimens of sooty molds associated with conifer leaves from Jurassic hot spring deposits of Patagonia, Argentina., Methods: Thin sections of chert samples from the La Matilde Formation, Deseado Massif (Santa Cruz, Argentina) were observed using light microscopy., Results: The fungi occur on the surface and axils of leafy twigs with podocarpaceous affinities, forming dense subicula comprised by opaque moniliform hyphae. Additionally, several asexual and sexual reproductive structures are observed. On the basis of vegetative (i.e., dense subicula composed of moniliform hyphae; hyphae composed of opaque cells deeply constricted at the septa) and reproductive characters (i.e., poroconidial and sympodioconidial asexual stages and diverse spores), two morphotypes were identified with affinities within lineages of the subphylum Pezizomycotina that encompass the ecological group of sooty molds, and a third morphotype was within the phylum Ascomycota., Conclusions: This finding extends the fossil record of sooty molds to the Jurassic and their geographic fossil range to the South American continent. In particular, their association with podocarpaceous conifers is shown to be ancient, dating back to the Jurassic. This new record provides an additional reference point on the diversity of interactions that characterized Jurassic forests in Patagonia., (© 2021 Botanical Society of America.)

Here we present a revision of the elaterate pollen species that belong to the genus Galeacornea. We also describe a new species, Galeacornea guayaguensis sp. nov., from the Early Cretaceous (Albian?) of central-western Argentina. The specimens from this species were retrieved from sediments of the Lagarcito Formation (San Luis Basin) located at the Sierra de Guayaguás ranges in the San Juan province. Galeacornea guayaguensis shares with the other Galeacornea species the shape of the grain and the presence of an annular rim and distal appendages. The ridge-like appendages of G. guayaguensis are similar to those of G. stoveri and G. tarimensis, although they never fuse with the annular rim or with each other at their ends as it respectively occurs in these species. This new pollen species provides further evidence on the morphological variation of elaterate grains and extends the geographical distribution of Galeacornea to southern South America, far beyond the palaeophytogeographic Albian–Cenomanian Elaterates Province of the equatorial region. Finally, we propose a new combination of the species Quantonenpollenites crassatus to Galeacornea crassatus, considering that the morphological features of the former perfectly fit the diagnosis of the genus Galeacornea. [ABSTRACT FROM AUTHOR]

Palynological analysis is reported here for the first time from glacial and postglacial deposits of the lower-middle section of the Guandacol Formation at the Huaco area, central Paganzo Basin, Argentina. Forty-nine spore species are assigned to twenty-seven genera and twenty-one pollen species are assigned to ten genera, however few acritarchs were identified. Biostratigraphic ranges of species suggest an age no older than late Serpukhovian for the section studied. This age is also supported by radiometric data that indicate an early Bashkirian age at the top of the Guandacol Formation. The palynofloras consistmostly of endemic spore species, and provide new evidence for delimiting the Subzone Aof the Raistrickia densa-Convolutispora muriornata Biozone in Argentina. Close correlation is suggested with palynological associations belonging to thewidespread glaciation occurred during the Serpukhovian-early Bashkirian in South America and Australia. [ABSTRACT FROM AUTHOR]

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