Biostratigraphy and evolution of Late Carboniferous and Early Permian smaller foraminifers from the Barents Sea (offshore Arctic Norway)

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Abstract
Nearly continuous cores from a 500-meter interval of upper Moscovian through post-Artinskian carbonate strata on the Finnmark Platform have yielded rich assemblages of fusulinaceans and smaller foraminifers. The fusulinaceans provide an independent time framework for evaluating stratigraphic occurrences of associated smaller foraminifers. Information derived from this study has been integrated with that from previous investigations to produce a smaller foraminiferal biostratigraphic model for the High Arctic. Kasimovian strata are characterized by occurrences ofNodosinelloidesspp.,Protonodosariaspp. andHemigordius schlumbergeri.Overlying lower Gzhelian beds are identified by the appearances ofRaphconilia modificataandAmphoratheca iniqua. Tezaquina clivuliandCribrogenerina gigasfirst occur in upper Gzhelian strata, and Asselian rocks contain appearances ofGeinitzina postcarbonicaandPachyphloiaspp. Phylogenetic reconstructions suggest that the Late Carboniferous-Early Permian pseudovidalinids (Archaediscacea) derived from the Pseudoammidiscidae, as did the older group of predominantly Early Carboniferous archaediscaceans. The repeated development of similar morphologies within the two groups of archaediscaceans includes examples of both convergence and iterative evolution. The Protonodosariidae and Syzraniidae most likely evolved from an earlandiid ancestor. The syzraniids gave rise to the Geinitzinidae, which in turn gave rise to the Pachyphloiidae. As in the archaediscaceans, evolution within and among the Earlandiidae, Protonodosariidae, Syzraniidae, Geinitzinidae and Pachyphloiidae includes multiple examples of repeated patterns. Two key phenotypic developments seemingly led to bursts of diversification in different groups throughout late Paleozoic foraminiferal evolution. The acquisition of an outer hyaline or pseudofibrous wall layer was a morphologic breakthrough followed by taxonomic radiation in both groups of archaediscaceans and in theEarlandia-Syzranialineage. The second major event was the shift from an undivided tubular morphology to uniserial morphology in both the Earlandiidae-Protonodosariidae and Syzraniidae-Geinitzinidae lines.Nodosinelloides pinardaeis proposed as a new name forNodosaria grandisLipina, 1949 (preoccupied).