Final answer:
A sagittal crest is a bony ridge on the top of the skull that indicates the presence of strong jaw muscles, typically associated with a diet requiring significant chewing force, such as a herbivorous diet or in some carnivores.
Step-by-step explanation:
A sagittal crest is a ridge of bone that runs along the top of the skull from front to back. This anatomical feature is found in the skulls of some mammals and is most prominent in species with strong jaw muscles. The presence of a sagittal crest usually indicates that the animal has large jaw muscles which are necessary for a diet that requires a lot of chewing forces, such as a diet consisting of tough, fibrous materials. Hence, animals with a sagittal crest are often associated with having a herbivorous diet that includes foods such as stems, leaves, and tough plant matter, although some carnivores like big cats that need strong biting forces also possess this trait.