Dendroid graptolites of the Ona Formation from Lower Silurian of the Western Sayan have been studied. The collection is represented by very well preserved specimens. It includes only benthic forms and is characterized by the complete absence of planktonic taxa. This is extremely rare for graptolite communities. Representatives of dendroid graptolites have retained their lifetime shape. The unbroken shape of rhabdosomes may indicate calm sedimentation environments, since it is benthic dendroid

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... aptolites that are very easily destroyed by underwater currents. Such type of autochthonous burial was previously studied by the authors on the territory of the Gorny Altai, and it is also known in the Lower Silurian of the Czech Republic.