Article: The Early Silurian atrypid brachiopod Alispira from western Canada
Alispira gracilis and Alispira tenuicostata previously have been known only from early Silurian rocks of the Siberian Platform and the eastern Baltic region. Here they are described from early Silurian (Llandovery) rocks of Canada, from the Beaverfoot Formation in the southern Rocky Mountains, the Nonda Formation in the northern Rocky Mountains (both British Columbia), and the Mount Kindle Formation in the District of Mackenzie. A third species, Alispira lowi, is described from the Severn River Formation in northern Manitoba. Other doubtful species of Alispira have been reported from southwestern and eastern Siberia and from northwestern China. In Siberia, Alispira has been reported to range from the early Llandovery to Wenlock. In Canada, associations of Alispira with Virgiana indicate a late Rhuddanian age for its earliest occurrence; the genus ranges up into the Aeronian and possibly into the Telychian but occurrences of Alispira with Pentamerus have not been documented. The distributions of Alispira gracilis and Alispira tenuicostata indicate close links between the early Silurian shelly faunas of the Siberian Platform and those of the cratonic regions of western North America.