Article: Late Cretaceous coprolites from western Canada

Abundant coprolites and possibly gut fills of holostean fishes are irregularly distributed throughout the kaolinitic clays and muds of the Whitemud Formation (late Cretaceous) of the Willows-Readlyn district, south-central Saskatchewan. The coprolites show a variety of internal and external structures including coiling, folding, and contraction marks of primary origin; secondary features, for example surface cracking, due to diagenetic replacement by siderite and pyrite, and subsequent alteration to iron oxides.