Deinosuchus was a prehistoric alligator that could grow to a length of 50 feet long. Deinosuchus was so big, it hunted dinosaurs. We know Deinosuchus hunted dinosaurs just because it was so huge and the fact that its jaws are meant to handle stuggling animals. But there's other evidence to support that. Paleontologists have found hadrosaur bones with bite marks that were the size of Deinosuchus teeth. But Deinosuchus was pretty much eating whatever it wanted to eat, large fish, pterosaurs, etc.