Two new reconstructions of Archaeopteris trees: Two different genera or various ecobiomorphs?

The article discusses new finds of wood of the genus Callixylon, discovered in Upper Devonian (Frasnian) deposits in the vicinity of the city of St. Peters-burg (Russia). The uniqueness of the find lies in the fact that for the first time a fragment of the trunk of archaeopterid plants with monopodially or pseudo-monopodially arranged perennial branches was discovered. In addition to the branches, there is a large branch scar on the trunk. A detailed description of the new find is provided. The morphology of both aboveground and underground parts of archaeopterid plants is discussed. The influence of archaeopterids on soil formation in the Late Devonian is debated. New data is provided on two “fossil forests” on the territory of Russia — on the Tsilma River, Middle Timan (uppermost Middle — lowermost Upper Devonian) and on the Volonga River, Northern Timan (Upper Devonian, Famennian). An analysis of previous recon-structions of Archaeopteris was carried out. Based on the data obtained during the study of the new find, as well as taking into account numerous observations of the morphology of archaeopterids previously carried out by the authors, two new reconstructions of trees of the biological genus Archaeopteris (in the mod-ern sense) have been proposed. The authors try to find arguments to explain the different morphologies of Archaeopteris plants — whether they were differ-ent ecobiomorphs or actually belonged to different biological genera. These questions, although they remain unanswered, are reflected in the reconstruc-tions proposed by the authors