New data on the morphology of permian gliding weigeltisaurid reptiles of Eastern Europe
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- Bulanov, V.V. & Sennikov, A.G. Paleontol. J. (2010) 44: 682. doi:10.1134/S0031030110060109
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New specimens of the Permian gliding reptile Rautiania from the Kul’chumovo-A locality (Russia, Orenburg Region) are described. The morphology of Rautiania strongly suggests adaptation for an obligatory arboreal mode of life and gliding flight (which are supported by the consolidated sacrum; free movements of the autopodial elements; specific manus morphology, typical of living arboreal vertebrates; strongly pneumatic structure of cranial bones and rodlike bones forming the frame of the gliding skin membrane; etc.). The homology of bones of the posterior wall of the temporal fenestra of weigeltisaurids is revised; according to the new concept, it consists of two dermal elements, the squamosal and quadratojugal. The outgrowths on the cranial bones of weigeltisaurids are of osteodermal nature. The diagnostic characters in the dental system of the genus Rautiania are considered, and the structure of the quadrate-articular complex of weigeltisaurids is described in detail for the first time. The original name of the family, Weigeltisauridae Kuhn, 1939, is restored. The appearance in the Late Permian of specialized gliding reptiles, such as the Weigeltisauridae, is accounted for by climactic conditions of terrestrial vertebrate communities in the pre-Triassic time, which resulted in the penetration of tetrapods into new adaptive zones, in particular, forest biotopes. The global distribution of weigeltisaurids is evidence of the widespread of high thin forests, the ecotopes most favorable for the appearance and subsequent dispersal of gliding animals, in the Late Permian and later on.