Stellarossica gen. nov. and the Infragroup Keltmiides infragroup. nov.: Extremely Large Acanthomorph Acritarchs from the Vendian of Siberia and the East European Platform

Abstract

The lower Vendian microbiota of the Ura Formation, Baikal-Patom Highland, eastern Siberia, contains remains of acanthomorph acritarchs almost 1 millimeter in diameter that is extremely large for Precambrian microfossils. The microremains have been described as the new genus and species Stellarossica ampla gen. et sp. nov., and altogether with the morphologically and dimensionally similar Pertatataka-type (ECAP) acanthomorph acritarchs Keltmia, Weissiella and Galeasphaeridium from the Vendian deposits of the East European Platform, are placed in the formal infragroup Keltmiides. Lower Vendian acanthomorph acritarchs are either interpreted as remains of giant algae or eggs (diapause egg cysts) of the earliest invertebrates, and the new finds tend to support the latter hypothesis.