Casts of Vertebrate Internal Organs from the Upper Cretaceous of Western Canada

Abstract

Casts of intestines exceeding 1 m in length have been excavated from the non-marine kaolinitic mudstones of the Whitemud Formation (late Cretaceous) in southern Saskatchewan. They are associated with hundreds of thousands of coprolites preserved in a channel-fill with fluvio-deltaic clastics overlying Bearpaw Formation marine shales. This deposit may represent the largest known accumulation of Cretaceous vertebrate coprolites from the North American Interior. The four known intestines are tightly sinuous without spiral coiling and with longitudinal lobes. Finely detailed surface striations and ridges preserve the texture of the gut wall, but no internal detail was observed in each intestinal specimen. The longitudinal muscles suggest a preservation of the large intestine, in contrast with the circular muscles of the small intestine. The intestinal specimens and coprolites are attributed to a herbivorous tetrapod because of the tightly packed sinuous gut.