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The Anisian (Middle Triassic) brachiopod fauna from Qingyan, Guizhou, south-western China

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journal contribution
posted on 08.11.2019 by Zhen Guo, Zhong-Qiang Chen, David A. T. Harper

Like most of the benthos, brachiopods suffered huge losses in biodiversity during the end-Permian extinction and did not fully recover until the Anisian (Middle Triassic). Anisian brachiopod faunas are thus a key clade characterizing the recovered marine ecosystems in the early Mesozoic. Of these, the brachiopod fauna from Qingyan Town in Guizhou Province, south-western China has long been one of the best-known Anisian faunas in the world. The taxonomy of the Qingyan fauna, however, was last studied half a century ago, and thus requires revision. Here we describe 34 species (and subspecies) (including seven undetermined species) assigned to 29 brachiopod genera from the Qingyan Formation from the Leidapo and Wachangpo localities in the Qingyan section. Of these, 11 species are described for the first time from this area. Two new genera: Parabrekia and Caucasorhynchella (= Crurirhynchella Xu & Liu, 1983, a nomen nudum) and seven new species (Angustothyris dagysi, Angustothyris qingyanensis, Koeveskallina bifurcata, Neocyrtina xui, Nudirostralina minuta, Parabrekia yangi and Rutorhynchia? trigonalis) are also erected. The Qingyan brachiopod fauna is characterized by abundant endemic genera (33.3%) and exhibits a weak similarity with several coeval faunas reported from the western Tethys. In addition, faunal affinity analyses of 13 Anisian brachiopod faunas indicate that at least five biogeographical provinces (western Tethys, eastern Tethys, northern Siberia, Himalayas and New Zealand) were present during the Anisian, and the eastern Tethys province included three subprovinces: Yangtze, southern Qilian–western Qinling and central Qinghai. However, most faunas mutually share rather low Jaccard similarity coefficients (<0.4), except for those in the western Tethys, implying a continuity of the multi-provincial pattern established for Early Triassic brachiopod distributions.