A New Kotlassiid (Amphibia, Seymouriamorpha) from the Terminal Permian of Eastern Europe
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New Kotlassiid (Amphibia, Seymouriamorpha) from the Terminal Permian of Eastern Europe V. V. Bulanova, b, * a
Borissiak Paleontological Institute, Russian Academy of Sciences, Moscow, 117647 Russia bKazan Federal University, Kazan, 420008 Russia *e-mail: [email protected] Received January 14, 2019; revised February 11, 2019; accepted February 14, 2019
Abstract—The first kotlassiid species of the Vyazniki Faunal Assemblade, Microphon terminalis sp. nov., is described from the terminal Permian of the Bykovka locality (Vladimir Region, Russia). The diagnostic characters of M. terminalis are the preservation of nasolacrimal duct throughout ontogeny and some features of the marginal teeth, such as the moderately thickened proximal parts of the crowns, sharply lingually recurved apices, presence of narrow shoulder-like projections of the cutting edges and strongly ornamented enamel. The tooth shape and the location of crista paraquadrata of the squamosal indicate that M. gracilis can be regarded as an ancestral species for M. terminalis that is confirmed by stratigraphic data. The dentition morphology suggests carnivorous mode of life of M. terminalis and show the prevalence of strongly chitinized invertebrates in its diet. This corresponds to the general evolutional trend in the Kotlassiidae (the abandonment of obligate algophagy as a general trophic specialization and the expansion of feeding preferences). Keywords: Kotlassiidae, Seymouriamorpha, Microphon terminalis sp. nov., terminal Permian, Vyaznikovian tetrapod assemblage, Eastern Europe, dentition DOI: 10.1134/S0031030120070035
INTRODUCTION The data on the Vyazniki Faunal Assemblage, concluding the Permian stage of evolution of the tetrapod communities in the Eastern Europe, is based mainly on the data obtained from the group of localities around the town of Vyazniki (Vladimir Region, Russia). There are many works on paleontology and stratigraphy of the alluvial–channel sedimentary complex represented here because of its terminal Permian position in the regional sequence and, as a consequence, the importance of the Vyaznikovian biota for reconstructing the Permian–Triassic extinction and the subsequent renewal of the faunal diversity of continental ecosystems in the Early Mesozoic (Aristov et al., 2014; Golubev, 2004; Golubev and Sennikov, 2015; Golubev et al., 2005; Lebedev et al., 2015; Newell et al., 2010; Owocki et al., 2012; Sennikov, 2009; Sennikov and Golubev, 2005, 2006, 2007, 2010, 2013). Due to its taxonomic uniqueness, the Vyazniki fauna has been of interest since the first finds of tetrapods by A.A. Dobrolyubov in 1951. Recently, the absence of cenotic equivalents outside the East European Platform has increased attention to this fauna. The main novelty of the Vyazniki Assemblage in comparison with the preceding Sokolki fauna is that gorgonopsians were replaced in the dominant block by large-sized theriodonts and proterosuchid diapsids
(Ivakhnenko, 2008; Sennikov, 1995), as well as a sharp reduction in the role of Pareiasauria among primary consumer
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