Final answer:
The significant evolutionary novelty of the ceratosaurs was serrated, blade-like teeth, which helped them consume prey efficiently.
Step-by-step explanation:
The question is related to the characteristics that distinguished ceratosaurs, a group of large predatory dinosaurs, from other dinosaur clades. Considering the options provided, serrated, blade-like teeth is a significant evolutionary feature that many theropod dinosaurs, including ceratosaurs, developed. This adaptation was crucial for their role as predators, enabling them to efficiently consume prey. Other options like a lachrymal fenestra (option D) do not represent a unique evolutionary novelty of ceratosaurs as such features were more widespread among various dinosaur groups.