Broad-ribbed spiriferid brachiopods are relatively common in the Permo-Pennsylvanian of northern Yukon Territory and, because of their ribbed pattern, tend to stand out from other spiriferids. Five species belonging to three genera are recognized. These are Choristites ussensis (Stuckenberg), Brachythyrina ufensis (Tschernyschew), Spirifer norini (Chao), S. nikitini Tschernyschew and S. osborni Harker.
Choristites ussensis, B. ufensis and S. norini are confined to the Pennsylvanian Ettrain Formation and Spirifer nikitini to the Wolfcampian Jungle Creek Formation. Spirifer osborni has not yet been positively identified from northern Yukon Territory. Its occurrence elsewhere suggests that if and when found, it will be in strata coeval with the Leonardian portion of the Tahkandit Formation.