Scientists say there’s new evidence that settles the origins of a mysterious dinosaur excavated in the 1940s. Researchers have long debated whether a dinosaur skull found in Montana decades ago was a young T. rex or another type of dinosaur. A research team studied a new complete skeleton from Montana and claim it identifies the mystery reptile as an adult and a new species. Not all scientists are convinced, and some say the other mystery skeletons could belong to a younger T. rex. The research was published Thursday in the journal Nature.