Historical Resources Impact Assessment and Mitigation studies have documented a new middle Cenomanian invertebrate fauna from the Shaftesbury Formation in the Birch Mountains, northwest of Fort McMurray, in northeastern Alberta, Canada. Although older portions (Albian) of the Shaftesbury Formation in Alberta and British Columbia have yielded invertebrate fossils, this is the first fauna of middle Cenomanian age known for the unit. The fauna includes the ammonites Acanthoceras wyomingense and Borissjakoceras orbiculatum, the inoceramid bivalves Inoceramus dunveganensis and Inoceramus prefragilis stephensoni, and the gastropod Pirsila tensa. The occurrence of the late middle Cenomanian zonal fossil A. wyomingense allows correlation between the middle “Fish Scales Formation” of the Shaftesbury Formation and the lower part of the Labiche Formation of Alberta, and with five units farther to the south in the United States, namely the Greenhorn Limestone, Lincoln Formation, and Graneros Shale of Kansas, the Frontier Formation of Wyoming, and the Belle Fourche Shale of Montana.
↵1 This article is one of a selection of papers published in this Special Issue commemorating the 30th anniversary of the Royal Tyrrell Museum of Palaeontology.
- Received September 30, 2014.
- Accepted March 2, 2015.
- Published on the NRC Research Press Web site at http://cjes.nrc.ca on August 5, 2015.
- Published by NRC Research Press