Investigating gut contents of the leptocleidian plesiosaur Umoonasaurus demoscyllus using micro-CT imaging

The holotype of Umoonasaurus demoscyllus (AM F.99374) is one of the most complete plesiosaur skeletons ever discovered in Australia. It preserves a gastric mass in the pectoral girdle region that has not yet been documented in detail. Here, we use high resolution micro-computed tomography (micro-CT) to image the gut contents of this specimen. These comprise 17 vertebrae from an unidentified teleost, together with at least 60 rounded gastroliths averaging about 5 mm in maximum length. Our study demonstrates the potential for 3D tomographic imaging to investigate Mesozoic marine reptile diets and ecology.