A fossil tooth found buried inside the healed tailbones of a duckbill dinosaur suggests the animal survived a close encounter with a Tyrannosaurus rex about 65 million years ago, according to a new study. Scientists say the embedded tooth, discovered in the Hell Creek Formation in Montana, is the first conclusive proof that T. rex was not just a scavenger, but also a predator that hunted and killed prey... But not everyone agrees. Jack Horner, a paleontologist at Montana State University who has long argued that T. rex was incapable of hunting healthy adult prey, remains unconvinced... The fossil evidence...