Tyrannosaur feeding traces on 'Deinocheirus' (Theropoda:?Ornithomimosauria) remains from the Nemegt Formation (Late Cretaceous), Mongolia

Bite marks attributable to 'Tarbosaurus bataar' are identified on fragments of gastralia from the giant putative ornithomimosaur, 'Deinocheirus mirificus'. Hundreds of bone fragments collected from the holotype quarry of 'D. mirificus' by members of the Korea-Mongolia International Dinosaur Project at Altan Uul III (Mongolia) were visually inspected for biomodification. Parallel striae and gouges were identified on two gastralia, which are interpreted as bite marks. Serration marks, interpreted from parallel striae, are broadly U-shaped and measure 0.5 mm in diameter. A comparison of these marks with the denticles of Nemegt theropods reveals the tyrannosaur, 'Tarbosaurus' as the most likely culprit. The identification of tyrannosaur bite marks on the bones of 'D. mirificus' sheds light on both the diet of 'Tarbosaurus' and the taphonomy of the only known specimen of 'Deinocheirus'.