Biostratigraphy and paleoecology of an unusual palynological record from the Aquidauana Formation, Late Pennsylvanian of Paraná Basin

The Aquidauana Formation is a Permo-Carboniferous sedimentary unit, widely stratigraphicaly distributed in the northwestern and northern portions of the Paraná Basin. However, little paleontological data is available from this formation, preventing accurate biostratigraphic and paleoecological interpretations. An abundant, diversified and well preserved assemblage of palynomorphs was recognized from sampling conducted in an outcrop section in Cipolândia District of Aquidauana Municipality, state of Mato Grosso do Sul, Brazil. A total of 35 indigenous palynomorph taxa was recognized, comprising 6 species of spores (related to 5 genera), 28 species of pollen grains (14 genera) and 1 species of chlorophycean algae. Monosaccate pollen grains are exceptionally dominant, representing 90.38% of the association, particularly constituted by species of the genera Cannanoropollis (30.41% of the total assemblage), Potonieisporites (28.14%) and Plicatipollenites (19.52%). This quantitative overrepresentation is not usual from Gondwana deposits, revealing a particular plant dominance of Cordaitales in the terrestrial flora. These results are interpreted as an upland ecology characterized by plants with a moisture-independent reproduction strategy, under a glacial climate influence. Certain species of pollen allow assignment of this assemblage to the Crucisaccites monoletus Zone (Late Pennsylvanian), which had been recognized only in the middle portion of the Itararé Group at the northeastern margin of the basin

Biocronoestratigrafia de miosporos do Devoniano Medio – Carbonifero inferior das bacias do Solimoes e Parnaiba (Estado da arte).

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Permian plants from the Chutani Formation (Titicaca Group, Northern Altiplano of Bolivia): II. The morphogenus Glossopteris

Fossil plants belonging to the morphogenera Glossopteris, Pecopteris and Asterotheca were collected from the upper part of the Chutani Formation (Titicaca Group), near the town of San Pablo de Tiquina, on the southeastern shore of Lake Titicaca (northern Altiplano, Bolivia). This paper presents the first description of specimens of the morphogenus Glossopteris from Bolivia. The Bolivian specimens of Glossopteris consist of poorly-preserved impressions, although they present the diagnostic features of this morphogenus. They are fragments of leaves with secondary veins of taeniopterid-type, typical of glossopterids from Late Permian deposits of Gondwana. The only species of Pecopteris confirmed in the first part of this study, i.e. P. dolianitii Rösler and Rohn (see Vieira et al. 2004), was previously reported from the Late Permian beds of the Rio do Rasto and Estrada Nova formations in the Paraná Basin (southern Brazil). Therefore, a Late Permian age is proposed for the fossil plant-bearing beds of the Chutani Formation based on the analyzed assemblage. The phytogeographic implications of this new find are briefly analyzed.<br>Plantas fósseis, pertencentes aos morfo-gêneros Glossopteris, Pecopteris e Asterotheca, foram coletadas na porção superior da seção aflorante da Formação Chutani, próxima ao povoado de San Pablo de Tiquina, sudeste do lago Titicaca (Altiplano norte, Bolívia). Este trabalho apresenta a primeira descrição de espécimes do morfo-gênero Glossopteris provenientes da Bolívia. Os espécimes estudados de Glossopteris consistem em impressões foliares pobremente preservadas nas quais feições diagnósticas estão presentes. Os fragmentos foliares apresentam venação secundária do tipo teniopteróide, uma característica típica de glossopterídeas encontradas em depósitos do Permiano Superior do Gondwana. Por sua vez, a única espécie de Pecopteris confirmada para estes níveis da Formação Chutani, i.e. P. dolianitii Rohn and Rösler (ver Vieira et al. 2004), foi previamente assinalada para estratos do Permiano Superior da Bacia do Paraná (formações Estrada Nova e Rio do Rasto). Portanto, uma idade neopermiana é tentativamente proposta para os níveis da Formação Chutani que contém a associação estudada. As implicações fitogeográficas deste novo achado são brevemente analisadas