The base of the Olenekian stage of the Early Triassic is at the lowest occurrence of Neospathodus waageni. It is defined as ending near the lowest occurrences of Chiosella timorensis.
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^Takumi Maekawa; Toshifumi Komatsu; Toshio Koike (2018). "Early Triassic conodonts from the Tahogawa Member of the Taho Formation, Ehime Prefecture, southwest Japan". Paleontological Research. 22 (s1): 1–62. doi:10.2517/2018PR001. S2CID134005889.
Taxonomy and correlation of Lower Triassic (Spathian) segminate conodonts from Oman and revision of some species of Neospathodus. M. J. Orchard, Journal of Paleontology, Volume 69, Issue 01, January 1995, pages 110–122, doi:10.1017/S0022336000026962