Abstract

A sequence of 20 m of Wenlockian graptolite-bearing strata is described from southern Northwest Territories. The sequence is relatively rich in graptolites and represents the best Wenlockian graptolite interval yet known in the Canadian Cordillera, even though the fauna is notably lacking in many of the typical Wenlockian species. The following Wenlockian biostratigraphic units are recognized (from oldest to youngest): centrifugus Zone, "Beds with C. cf. perneri", rigidus Zone, "Beds with Monograptus firmus nahanniensis", testis-lundgreni Zone, and "Beds with Pristiograptus etheringtoni".Graptolites described in this study comprise Monograptus antennularius, M. firmus nahanniensis n. subsp., M. flemingii, Pristiograptus sardous, P. etheringtoni n. sp., Monoclimacis flumendosae, Cyrtograptus centrifugus, C. cf. hamatus, C. cf. perneri, and C. rigidus from Wenlockian strata, as well as the first report from outside China of the late Llandoverian genus Sinodiversograptus.

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