Strobilus organization in the enigmatic gymnosperm Bernettia inopinata from the Jurassic of Germany

Abstract

The enigmatic fossil Bernettia inopinata from Lower Jurassic strata of Upper Franconia, Germany, has been described as a leaf-like structure a leaf-like structure bearing a proximal cluster of densely spaced, pillow-like objects believed to represent ovules or ovule-containing units. The systematic affinities of B. inopinata have remained unresolved. This paper describes five strobili from Pechgraben near Bayreuth that show fertile units composed of B. inopinata and the delicate leaf-like structure Chlamydolepis lautneri in helical arrangement along a central axis. These fossils provide the first insights into the organization of the B. inopinata reproductive structure and demonstrate that B. inopinata and C. lautneri were produced by the same plant. Moreover, Desmiophyllum gothanii leaves closely associated with the strobili, together with specimens showing C. lautneri and the enigmatic microsporophyll Piroconites kuespertii in organic connection, support the hypothesis that these four taxa represent parts of the same plant. The genus Piroconites with its type-species P. kuespertii is validated. Although certain structural details of the B. inopinata plant are reminiscent of features seen in other gymnosperms, including Bennettitales (i.e. ovule structure, megasporophyll organization, microsporophyll organization), Gnetales (i.e. three-locular synangia, pollen, leaves), Glossopteridales (megasporophylls), and conifers (microsporophyll organization and arrangement), it does not fit well into any of the known groups of gymnosperms.