A ridge of bone running lengthwise along the midline of the top of the skull of many mammalian and reptilian skulls and serves as an attachment site for the temporailis muscle[WP,modified]. [ http://en.wikipedia.org/wiki/Sagittal_crest ]
Synonyms: crista sagittalis externa
Term information
The sagittal crest serves primarily for attachment of the temporalis muscle, which is one of the main chewing muscles
Skulls of some dinosaur species, including tyrannosaurs, possessed well developed sagittal crests. Among mammals, dogs, cats, lions, and many other carnivores have sagittal crests, as do some leaf eaters, including tapirs and some apes. Sagittal crests are found in robust great apes, and some early hominins. Prominent sagittal crests are found among male gorillas and orangutans, and do occur but only rarely in male chimpanzees such as Bili Apes