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 Urdyella unicorna n. sp. Fig. 26A–W , AE? 1970 Neospathodus peculiaris Sweet ?; Hasenmüller, p. 62, pl. 2, fig. 10 2005 Aduncodina unicosta Ding ; Zhao, pl. 6, nr. 9–10. Etymology : Named after the unicorn, a mythical creature with a single horn on its forehead, for the huge cusp of theP 1 element of this species. Holotype : specimen illustrated in Fig. 26A . Paratypes : specimens illustrated in Fig. 26K, Q, W . Type locality: Laren road cut, Luolou formation, Guangxi Province , China . Type level : Luolou Formation, upper Owenites to lower Anasibirites beds, middle Smithian to early late Smithian, Olenekian, Early Triassic . Number of specimens .> 40. Diagnosis. P 1 : Short coniform-to-segminiscaphate element with a very long, needle-like, recurved cusp, sometimes one (or two in large specimens) tiny, anterior denticle, and a broadly excavated basal cavity. Description . P 1 : Te cusp is about 3–4 times longer than the basal cavity is broad, is usually slightly recurved, sometimes only reclined, and it makes an angle of about 40°–60° with the baseline of the lower margin in lateral view. Many specimens are coniform and may bear a tiny anterior process, some (usually larger) specimens have a very short anterior process bearing up to two anterior denticles and may be better described as segminiscaphate. Te deep basal cavity is oval to drop-shaped in aboral view. In lateral view, the base of the cusp occupies the anterior half of the basal cup. Remarks. Specimens of this species were found by Zhao et al., (2007, without illustrations; but two specimens are illustrated in Zhao’s Ph.D thesis, 2005) in coeval strata of the Chaohu section, Anhui Province but reported as Aduncodina unicosta , a possibly related form that in all our collections from China is otherwise restricted strictly to the Spathian interval. Occurrence. India : Mud, Mikin Formation, maximal horizon 1 ( Goudemand, 2011 ); Western USA , Parachirognathus-Furnishius zone, Taynes Formations, Utah (Hasenmüller, 1970). South China : Chaohu section, Anhui Province ( Zhao, 2005 ; Zhao et al., 2007 ); Pingtang Syncline, uppermost Daye Formation and Luolou Formation, Smithian (this paper). Upper Smithian, Khunamuh Formation, Guryul Ravine, Northern Indian Margin (Leu et al. in prep.), Oman (Leu et al. submitted).