A Unitary Association-based conodont biozonation of the Smithian-Spathian boundary (Early Triassic) and associated biotic crisis from South China Author Leu, Marc Paleontological Institute and Museum, University of Zurich, Karl-Schmid-Strasse 4, 8006 Zurich, Switzerland Author Bucher, Hugo Paleontological Institute and Museum, University of Zurich, Karl-Schmid-Strasse 4, 8006 Zurich, Switzerland Author Vennemann, Torsten Author Bagherpour, Borhan Author Ji, Cheng Author Brosse, Morgane Author Goudemand, Nicolas text Swiss Journal of Palaeontology 2022 19 2022-11-22 141 1 1 61 http://dx.doi.org/10.1186/s13358-022-00259-x journal article 10.1186/s13358-022-00259-x 1664-2384 PMC9681704 36439694 12000082 DE44D675-5D51-45FA-B134-C9203659E6B9 Genus GUANGXIDELLA Zhang & Yang, 1991 Type species . Neoprioniodus bransoni Müller 1956 , p. 829 , pl. 95, figs. 19–21. Type stratum and locality . Smithian ammonoid bed, Crittenden Springs , Elko County , Nevada .