In this environment , it was a predator at the top of the food chain , probably preying on other large dinosaurs like the hadrosaur Saurolophus or the sauropod Nemegtosaurus . In this environment , it was an apex predator at the top of the food chain , probably preying on other large dinosaurs like the hadrosaur Saurolophus or the sauropod Nemegtosaurus .