Crystal structure of phosphonium carboxylate complexes. the role of the

Abstract

© 2015, Pleiades Publishing, Ltd. A huge dipnoan, Permoceratodus gentilis Krupina, gen. et sp. nov. (order Ceratodontiformes), from the terminal Permian beds (Zhukovian Regional Stage, Vyatkian Stage, Upper Permian) of the Sokovka locality (Vladimir Region) is described. It is characterized by the evolutionarily advanced high extent of fusion of skull roof bones and conservative well defined structures of the seismosensory system of the head. This combination distinguishes the new taxon from other Ceratodontiformes. A set of conservative and advanced characters is observed in many vertebrates of the Vyazniki faunal assemblage. Large tetrapods and fishes characterize the terminal developmental stage of the Permian fauna of Eastern Europe, which was followed by impoverishment of the taxonomic composition accompanied by a decrease in body size. The dipnoan described here, like some other vertebrates of this assemblage, belong to high-rank taxa, which had just appeared in the Paleozoic, but reached flourishing in the Mesozoic.