Unique 3D preservation of Rhuddanian (Silurian) Callograptidae (Gorny Altai, Russia)

We studied a collection of the Silurian (Rhuddanian) multi-branched dendroids, including reticulate, benthic dendroid graptolites of the Callograptidae Hopkinson (in Hopkinson and Lapworth, 1875), from the Gorny Altai, Russia. Species of Dictyonema Hall, Koremagraptus Bulman, Callograptus Hall, and Desmograptus Hopkinson were identified and described. The graptolites are represented by in situ burial of colonies with 3D preservation of tubaria (= rhabdosomes). Complete (intact) colonies of dendroid graptolites are characterized by successive development stages: juvenile, neanic, ephebic (adults), while the general configuration of the tubarium changed from the proximal to distal. In a number of cases, later stage of colony development — the gerontic stage (senilis) is found. We carried out morphological analysis of dendroid graptolite tubaria (Callograptidae) of various development stages, showing eight morphotypes of the colonies, namely, the cylinder, disc, disc on a stem, hemisphere, cone, wineglass, blooming flower, and funnel type.