Microfossils associated with Carboniferous Macgowanella and Sinopora? pascuali allow more precise age determinations than previously determined. Macgowanella, a possible bryozoan holdfast, is represented by two species, M. tenuiradiata (Warren) and M. stellata (Warren), both from the Viséan (Upper Mississippian, Meramecian) Mount Head Formation of the southern Canadian Rocky Mountains. Microfossils indicate a correlation with upper Viséan Zone 14, equivalent to the lower upper Meramecian Marston/lower Opal members of the Mount Head Formation.The syringoporid coral Sinopora? pascuali is from near Kamloops, British Columbia. Microfossils support the Early Pennsylvanian date earlier assigned, correlating it with Zones 20 or 21, Bashkirian = Morrowan to basal Atokan.