A Late Ordovician brachiopod fauna from the Black River quadrangle (D-1 1:63,360 scale) of east-central Alaska comprises taxa typical of the Late Ordovician brachiopod fauna in the pericratonic epeiric seas of Laurentia, including Hesperorthis pyramidalis, Plaesiomys occidentalis, Eoplectodonta sp., Holtehdalina sp., Leptaena sp., Brevilamnulella minuta n. sp., Tcherskidium tenuicostatum n. sp., Rhynchotrema iowense, and Whitfieldella sp. The presence of Plaesiomys occidentalis and Tcherskidium tenuicostata n. sp. indicates a latest Katian age by correlation with similar species in the Mackenzie Mountains, southern Manitoba, Anticosti Island, the American mid-continent, Kolyma, and Siberia. Cluster analysis based on 20 well-studied late Katian brachiopod faunas from various regions within Laurentia and elsewhere in other tectonic plates suggests that the small brachiopod faunule from Alaska has the strongest paleobiogeographic affinity with Laurentia, confirming that the Black River quadrangle of Alaska was part of Laurentia during the Late Ordovician.

Cluster analysis of late Katian (Richmondian) brachiopod faunas from Laurentia and other tectonic plates (Fig. 2 of the main paper) is based on following sources (Table S1). Anticosti Island, Quebec, Vaureal Formation (Dewing, 2000, Jin and Zhan, 2008). Cincinnati Arch, Richmondian strata of Ohio-Kentucky-Indiana border region (Davis, 1985). East-central Alaska (this study). Farewell Terrane, Upper Katian strata, western Alaska (Rasmussen et al., 2012). Hudson Bay, Churchill River Group (Jin et al., 1997). Manitoba, Stony Mountain Formation (Jin and Zhan, 2001). Mackenzie Mountains, western marginal platform; lower Whittaker Formation (updated, this study). Iowa, upper Maquoketa Group (Wang, 1949). Texas, Montoya Group, Trans-Pecos Texas (Howe and Reso, 1967). Tennessee, Fernvale Formation (Howe, 1988). Oklahoma, Unit 3C, Viola Springs Formation (Alberstaft, 1973). Wyoming, Bighorn Dolomite (Macomber, 1970). Avalonia: England–Wales–southern Ireland (Cocks, 2008). Baltica, Estonia and Lithuania, Pirgu Stage (Paškevičius, 1994; Hints and Harper, 2003; Rõõmusoks, 2004). Boda Limestone, Sweden, Baltica (Cocks, 2005). Gorny Altai, Orlov Horizon (Kulkov and Severgina, 1989). Kazakhstan, upper Chokpar Formation and Dulankara Horizon, Dulankara, (Nikitin et al. 2006). Scotland, Girvan district, (Cocks, 2008). Sette-Daban, Siberian Platform, Nirunda and Bur horizons (Rozman, 1970; Yadrenkina, 1978). South China, Xiazhen Formation, JYC area (Zhan and Cocks, 1998). Taimyr, Siberian Platform, Korotkinskaya Formation (Cocks and Modzalevskaya, 1997; Modzalevskaya; 2003).

Faunal data collected and updated based on primary taxonomic publications: 

References (in addition to References of the main paper)

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Cocks, L.R.M., 2008, A revised review of British Lower Palaeozoic brachiopods: Monograph of the Palaeontographical Society, v. 161, 276 p.

Cocks L.R.M., and Modzalevskaya, T.L., 1997, Late Ordovician brachiopods from Taimyr, Arctic Russia, and their paleogeographic significance: Palaeontology, v. 40, p. 1061–1093.

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Rozman, Kh.S., 1970, Stratigrafiya i brakhiopody srednego i verkhnego ordovika khr. Sette-Daban i verkhnego ordovika Selennyakhskogo kryazha: Geologicheskiy Institut, Akademiya Nauk SSSR, Trudy 205, p. 8–143.

Yadrenkina, A.G., 1978, Brachiopods: Transactions of the Institute of Geology and Geophysics, v. 340, p. 69–90. [in Russian]

Zhan R.B., and Cocks, L.R.M., 1998, Late Ordovician brachiopods from the South China plate, and their palaeogeographical significance: Special Papers in Palaeontology, v. 59, 70 p.

The dataset is binary: present = 1, absent = 0