Communities and paleoecology of Eifelian (mid-Devonian) brachiopods from the Bird Fiord Formation of Arctic Canada

The carbonate–siliciclastic strata in the Bird Fiord Formation of Arctic Canada contain a diverse brachiopod-dominated biota. A collection of 46 381 brachiopods from 126 sites at 35 localities on Ellesmere Island, North Kent Island, Grinnell Peninsula (Devon Island), and Bathurst Island includes 22 species assigned to 21 genera. Many of these taxa are endemic to Arctic Canada. Each collection of brachiopods is typically dominated by only one or two taxa. Cluster analysis, based on binary data, shows that the brachiopods can be divided into an Atrypa–Elythyna community group and a Spinatrypina–Desquamatia community group. The former encompasses the Atrypa–Elythyna and Atrypa–Elythyna–Perryspirifer communities, and the latter includes the Spinatrypina–Desquamatia and Spinatrypina–Desquamatia–Cranaena communities. The distribution of these communities was primarily related to water depth. Thus, the Atrypa–Elythyna community group, which belongs to benthic assemblage 3, lived in a shallow, proximal-shelf environment. The Spinatrypina–Desquamatia community group, which belongs to benthic assemblage 4, lived in a deeper, distal-shelf environment.