A fossil known as the Dueling Dinosaurs goes up for auction in New York on Tuesday.
It is two intertwined dinosaur skeletons, one carnivore, one herbivore, that appear to be caught in duel to the death. The fossil is scientifically significant due to the active pose, but it may never be studied.
National Geographic dinosaur writer Brian Switek joins the show to discuss why the secrets of the Dueling Dinosaurs could be lost in the confines of a private collection.