Genera Estoniocaulis Obut et Rotsk, 1958 and Rhadinograptus Obut, 1960 were erected as inocaulid and dithecoid graptolites. The type material of these taxa was reexamined. It was shown that all elements of their "rhabdosomes" are composed of a solid, granular or homogenous material and do not show the slightest traces of fusellar structure, presence of thecal cavities or stolons. Therefore, there are no doubts that both forms do not represent graptolites.
The "rhabdosomes" of E. jaervensis are composed only of solid, roller-like elements resembling melanosclerites. Skeletal material of Rh. jurgensonae consists of solid segments and flat appendices.
The results support the author's earlier opinion that the orders Dithecoidea and Inocaulida should be interpreted as proposed on the basis of superficial similarities of organic fossils representing distant systematic groups (Mierzejewski 1986). |
