Late Ordovician brachiopods from east-central Alaska, northwestern margin of Laurentia

Abstract

AbstractA 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, includingHesperorthis pyramidalis(Twenhofel, 1928),Plaesiomys occidentalis(Okulitch, 1943),Eoplectodontasp.,Holtehdalinasp.,Leptaenasp.,Brevilamnulella minutan. sp.,Tcherskidium tenuicostatumn. sp.,Rhynchotrema iowenseWang, 1949, andWhitfieldellasp. The presence ofPlaesiomys occidentalisandTcherskidium tenuicostatan. sp. indicates a latest Katian age by correlation with similar species in the Mackenzie Mountains, southern Manitoba, Anticosti Island, the American midcontinent, 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.UUID:http://zoobank.org/6b387856-61d5-4685-a592-faf5287c1e0f