Graptolites have been collected from sections through Lower Ordovician strata in northern Iran. At the Saluk Mountains, in the Kopet–Dagh region, mudrocks yielded fragmentary tubaria of Rhabdinopora sp. cf. R. flabelliformis, indicating the presence of lower Tremadocian strata there; stratigraphically, they lie between two limestone beds with the euconodont Cordylodus lindstromi. At Simeh–Kuh in the eastern Alborz Mountains (Semnan Province), upper Tremadocian – lower Floian strata include laminated dark mudstones that contain restricted graptolite faunas, mainly of small declined didymograptids; these are thought to represent incursions of plankton during periods of marine highstands. The lower major flooding surface in Simeh–Kuh coincides with an invasion of the graptolite biofacies and an incursion of Hunnegraptus? sp.; the second major flooding surface is associated with an incursion of Baltograptus geometricus. They were most probably synchronous with those in the lower part of the Hunnegraptus copiosus Biozone and at the base of the Cymatograptus protobalticus Biozone in the of the Tøyen Shale Formation succession of Västergötland, Scandinavia, suggesting that observed characters of sedimentation were eustatically controlled.

Twenty-two graptolite species are described from the Tremadoc portion of the Road River Group. In a 220 m thick, graptolite-rich section on Peel River, six graptolite biozones are recognized which in ascending order are: Staurograptus dichotomus, Anisograptus matanensis, Adelograptus cf. A. tenellus, Adelograptus antiquus, Kiaerograptus pritchardi and Paradelograptus kinnegraptoides. The Psigraptus fauna appears to be confined to a single bedding-plane within a thick interval dominated by Adelograptus cf. A. tenellus, and for this reason we propose a new zone characterized by the latter species rather than identify a Psigraptus Biozone as in China. The Adelograptus cf. A. tenellus Biozone has yielded Adelograptus? bulmani Spjeldnaes 1963, which we propose as the type species for the new genus Ancoragraptus. Graptolites recorded from the Tremadoc of the Yukon for the first time are: Ancoragraptus bulmani, Clonograptus magnificus, C. cf. C. multiplex, C. cf. C. rigidus, Hunnegraptus copiosus, Kiaerograptus? bulmani and K? kutchini sp. nov.