The Dilophosauridae was the first major radiation of large theropods. Dilophosaurids are famous for their striking head crests and the large knot in the upper jaw where the maxilla and premaxilla skull bones meet. This made them look like they had a perpetual snarl. In the early Jurassic, the super continent of Pangea was only beginning to split apart. No oceans to stand in the way of dilophosaurids spreading across the globe. As a result they are found all over the world. Even in the Antarctic.