Quick question: What had eight horns, two feet, a narrow snout, and snacked on herbivorous dinosaurs for lunch? The answer is a brand-new species of tyrannosaur, Alioramus altai, which prowled eastern Asia during the late Cretaceous period. Besides its bizarre horns, the interesting thing about this new Alioramus is that it weighed about half as much as the contemporary Asian Tarbosaurus, only about 1,000 pounds fully grown. What this shows, according to a new paper in The Proceedings of the National Academy of Sciences, is that predator-prey ecosystems in the Mesozoic Era were much more complicated than previously thought.
Now, about those horns. It's hard to extrapolate their purpose from a single fossil, but (since they were only about five inches long) they were probably a sexually selected characteristic, meaning a male Alioramus with longer, more impressive horns was more likely to score with females of the species. On the other hand, it's also possible that the horns had a specific, non-sexual purpose that paleontologists have yet to figure out!