Sagittal crest

A sagittal crest usually develops during the juvenile stage of an animal in conjunction with the growth of the temporalis muscle, as a result of convergence and gradual heightening of the temporal lines.

[citation needed] A sagittal crest tends to be present on the skulls of adult animals that rely on powerful biting and clenching of their teeth, usually as a part of their hunting strategy.

Among mammals, dogs, cats, lions, and many other carnivores have sagittal crests, as do some leaf eaters, including tapirs and some apes.

[citation needed] Sagittal crests are found in robust great apes, and some early hominins (Paranthropus).

The prominence of the crest appears to have been an adaptation for the P. aethiopicus' heavy chewing, and the Black Skull's cheek teeth are correspondingly large.