Scientists have long puzzled over the origins of a mysterious dinosaur excavated in the 1940s: Was it a young T. rex or another type of dinosaur? At first, researchers had only a tyrannosaur skull to ...

It's known as the "Dueling Dinosaurs" fossil: A triceratops and a tyrannosaur, skeletons entangled, locked in apparent combat right up until the moment of their mutual demise. Even in the Hell Creek ...