Conodonts identify the lower–middle Norian boundary in association with ∼224 Ma U–Pb dates from the Nicola Group, southern British Columbia, Canada

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Conodont faunas from the Castillion Member of the Selish Formation (Nicola Group) in the Merritt area of southern British Columbia, Canada, are described and determined to be early to mid-Norian in age based on biozonation established in the Pardonet Formation in NE British Columbia supported by successions in central Europe. The conodonts from two localities (Iron Mountain, Castillion Creek) show evolutionary trends through a younging sequence that serve to date and subdivide it. Hence, Ancyrogondolella vialovi is succeeded by A. ferrata n. sp. at Iron Mountain, and A . castillionensis n. sp. follows at Castillion Creek. Similarly, A. triangularis n. subsp. B is succeeded by A. diakowi , and A. uniformis is followed by A. equalis and Epigondolella tozeri . Finally, A. transformis appears as an end member and index for the Lacian–Alaunian substage boundary zone. Zircons extracted from interbedded volcaniclastics of the Castillion Member have yielded high-precision U–Pb ages of ∼224.5 Ma for the transformis Zone. This unequivocally supports the ‘long Norian’ with its base at ∼227 Ma but contrasts strongly with the astrochronologic estimate of 217.5 Ma for base Alaunian, which appears to consume most of Norian time. There is no clear explanation for this discrepancy.