Mammillichnis monstrum isp. nov., a new sea anemone trace fossil from the Carboniferous of the Donets Basin, Ukraine

A new ichnospecies Mammillichnis monstrum isp. nov. (Domichnia) is described from turbidite sandstone in the upper part of Mospyne Formation (late Bashkirian, Early Pennsylvanian) southern Luhansk Oblast, eastern Ukraine. represented by hypichnial, hemispherical, slightly flattened passive fillings a large burrow; apex burrow casts has concentric depression or small rounded tubercle. differs aggeris Chamberlain, 1971 (Vendian–Oligocene) and jakubi Pokorny et al., 2017 (Late Miocene, Neogene) its much larger size. The depth burrows varies greatly, which seems to be related different preservation casts, as well as, apparently, maturity producers. In addition, such an important diagnostic feature tubercle at not observed all specimens, probably also due types trace fossils. Perhaps, differences morphology some examined specimens are activity organisms that lived after death fossil producer. producers fossils apparently sea anemones (Actiniaria). record Actiniaria significant gaps because these animals lack mineral skeleton can preserved fossil. oldest known Vendian; there no data on post-Carboniferous Actiniaria. It only way study evolution this group studying their fossils, (e.g. ichnogenera Astropolichnus, Bergaueria, Conostichus, Kulindrichnus), demonstrate details body marks insignificant pauses sedimentation preceding accumulation sandstones. coarse sandy sediments mainly depressions left sessile coelenterates. Trace lenses poorly others. This circumstance intensity erosive turbidity currents.