Sporophyll morphology and reconstruction of the heterosporous lycopod Tomiostrobus radiatus Neuburg emend. from the Lower Triassic of Siberia (Russia)

Abstract

The paper deals with the taxon Tomiostrobus radiatus Neuburg emend., a heterosporous isoetopsid lycopod from the Babiy Kamen Locality of Lower Triassic of Siberia (Russia). Morphological diversity of the T. radiatus sporophylls is described in detail. Interpretation of structure and function of the sporophylls, and analysis of their morphological peculiarities are given. Arguments for attributing the lycopod T. radiatus to the Isoetaceae family have been provided. The reconstruction of T. radiatus is proposed. Origin and evolution of the families Isoetaceae and Pleuromeiaceae are also discussed.