Sommerxylon spiralosus from Upper Triassic in southernmost Paraná Basin (Brazil): a new taxon with taxacean affinity

Anais da Academia Brasileira de Ciências

Etiene F. Pires¹  Margot Guerra-sommer¹ 

[1] ,Universidade Federal do Rio Grande do Sul Instituto de Geociências Departamento de Paleontologia e EstratigrafiaPorto Alegre RS ,Brasil

关键词: fossil wood;    taxacean affinity;    Upper Triassic;    Paraná Basin;    lenho fóssil;    afinidade com taxaceae;    Triássico Superior;    Bacia do Paraná;   

DOI  :  10.1590/S0001-37652004000300013

来源: SciELO

【 摘 要 】

The anatoical description of silici?ed Gymnospermae woods from Upper Triassic sequences of southernmost Paraná Basin (Brazil) has allowed the identi?cation of a new taxon: Sommerxylon spiralosus n.gen. et n.sp. Diagnostic parameters, such as heterocellular medulla composed of parenchymatous and sclerenchymatous cells, primary xylem endarch, secondary xylem with dominant uniseriate bordered pits, spiral thickenings in the radial walls of tracheids, medullar rays homocellular, absence of resiniferous canals and axial parenchyma, indicate its relationship with the family Taxaceae, reporting on the first recognition of this group in the Triassic on Southern Pangea. This evidence supports the hypothesis that the Taxaceae at the Mesozoic were not con?ned to the Northern Hemisphere.

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