Planatophyton gen. nov., a late Early or Middle Devonian euphyllophyte from Xinjiang, North-West China
Résumé
A new euphyllophyte, Planatophyton hujiersitense gen. et sp. nov., is described on the basis of adpression fossils collected from a late Early or Middle Devonian locality from the Hujiersite Formation in the Hujiersite area, Hoboksar County, North Xinjiang, North-West China. The plant is possibly rhizomatous and comprises main axes with alternately inserted lateral branching systems. All axis orders bear large triangular enations all over their surface. Lateral branching systems are up to six times dichotomous. Dichotomies in lateral branching systems occur in the same plane, which results in bilaterally symmetrical, two-dimensionally branched organs, with limited overlapping between any segments. Distal segments in sterile lateral branching systems look slightly flattened and/or webbed. The ultimate segments of fertile lateral branching systems bear Psilophyton-like pairs of pendulous twisted sporangia. Anatomy and spores of the plant are unknown. The implications of the new plant for the early evolution of multiveined leaf are evaluated.