Gastroliths and Deinonychus teeth associated with a skeleton of Tenontosaurus from the Cloverly Formation (Lower Cretaceous), Montana, USA

Abstract

Tenontosaurus tilletti was an abundant ornithischian dinosaur from the Lower Cretaceous of North America, commonly regarded as a ‘basal’ iguanodontian. Here, we describe a remarkably well-preserved specimen, comprising a near-complete skeleton and skull, from the Cloverly Formation, Montana, USA, currently housed at the University of Manchester Museum, UK. Found alongside the specimen were alleged gastroliths, cycad seeds, and teeth of the contemporaneous dromaeosaur Deinonychus antirrhopus, all of which were buried in an alleged ash. We assess the credibility of these claims, using X-ray CT scanning and X-ray fluorescence (XRF) respectively, and show that the ‘seeds’ are non-organic mineral concretions, and that the ‘ash’ is actually a lime mud with a silica content of approximately 7%. We confirm the identification of the gastroliths and the Deinonychus teeth, providing further evidence to support the long-standing assertion, originally made by John Ostrom in 1970, that Tenontosaurus was a common food item for Deinonychus.