Schizoneura gondwanensis feistmantel da formação Rio do Rasto (Bacia do Paraná, permiano superior) no estado do Paraná e no norte do estado de Santa Catarina

Rosemarie Rohn, Oscar Rösler

Resumo


Specimens of Schizoneura gondwanensis are here described from 13 new outcrops of the Rio do Rasto Formation (Passa Dois Group, Paraná Basin, Upper Permian) in Paraná State and northern Santa Catarina State. This species was previously known in Brazil from only two other locaiities of the same formation. The foliage shoots, preserved as impressions in red and gray mudstones, siltstones and fine sandstones, generally occur as fragments, which may, however, exhibit well-preserved details such as possible structures of the mesophyll and epidermis, only very rarely recognized in other Gondwana specimens of Schizoneura. The fossils also corroborate Feistmantel's observations made in 1880, but overlooked by many later authors, regarding the embracing of the leaf clusters at the nodes, commissural lines, veins, etc. Although the leaf clusters at one outcrop are oblong-oval and not oval-lanceolate as at the other outcrops, ali are tentatively considered as belonging to the same species. Several of the leaf clusters of S. gondwanensis present ruptures along the commissural lines, here interpreted as the result of taphonomic processes or, possibly, environmental factors that affected the living plant. Ontogenetic aspects of Schizoneura and comparisons with Cathaysian representatives of this genus are also discussed. S. gondwanensis thus has a much broader geographical range in Brazil than previously thought and, consequently, can now be considered as one more important element of Rösler's Taphoflora E

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DOI: http://dx.doi.org/10.11606/issn.2316-8986.v17i0p27-34

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