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 Discretella aff. discreta ( Müller, 1956 ) Figs. 15B, J ; 16C ?. 1989 Neospathodus bransoni (Müller) ; Tang, p. 417, pl. 29, fig. 10. 2009 Guangxidella ? sp. A; Orchard & Zonneveld, p. 780, fig. 14, parts 33, 34. 2013 Discretella discreta (Müller) ; Yan et al., p. 516, fig. 6W. Number of specimens:>15 Diagnosis. Segminate P 1 element with rounded, upturned basal cavity at the posteriormost part. Large conspicuous cusp above basal cavity. Discrete, smaller upright denticles in the anterior part. Description. Tese P 1 elements have markedly discrete denticles and a large cusp. Te lower margin is straight in the anterior and upturned at the posterior part. Te basal cavity is drop-shaped, being rounded at the posterior edge and tapered at the anterior end. Te cusp is relatively large and reclined. A small, accessory, posterior denticle is occasionally present. Remarks. In comparison to Discretella discreta , this species has a rounded posterior margin of the basal cavity, more discrete denticles and the cusp is relatively larger and often recurved. In lateral view, the lower margin is upturned as in morphotype B of Discretella discreta (Maekawa & Igo, in Shigeta et al., 2014 ). Occurrence . Luolou formation, Owenites beds Smithian age, Shanggang road cut, Guangxi , South China .