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 ...

For decades, paleontologists have debated whether a small tyrannosauroid skull found in 1942 belonged to a juvenile T. rex or was a full-grown member of a previously unknown species, eventually dubbed ...