A remarkable mass-assemblage of lycopsid remains from the Rio Bonito Formation, lower Permian of the Paraná Basin, Rio Grande do Sul, Brazil

Abstract

Arborescent and sub-arborescent lycopsids are important floristic elements of the Brazilian early Permian post-glacial environments. However, the taxonomy and systematic position as well as the biology and ecology of these plants are poorly understood. The present study describes a remarkable assemblage of Brasilodendron cf. pedroanum axes preserved in the plant bearing sub-level N8b of the Morro do Papaleo outcrop, Rio Bonito Formation, early Permian of the Parana Basin, Rio Grande do Sul state, Brazil. These axes are massively concentrated, without any preferential depositional orientation, forming a monotypical assemblage. They are unbranched and preserved as impressions. Three morphological patterns, occurring on distinct axes, were described for leaf cushions. This mass-assemblage is probably a result of allochthonous deposition and hydraulic size-sorting. The massive concentration of B. cf. pedroanum suggests that this fossil taxon was an important floristic element somewhere in the upstream area of the braided river system studied here.