![]() ![]() In male gorillas and orangutans (and some species of fossil hominin), in which very large chewing muscles are anchored to a relatively small cranial vault, the right and left superior temporal lines not only converge at the midline of the top of the cranial vault (along the sagittal suture), but also require the development of a sagittal crest to provide sufficient attachment area for the temporalis muscles. In apes the superior extent of the temporalis muscles is positioned higher on the cranial vault (because brain size is smaller, and the muscles of mastication are larger than those found in humans), such that the right- and left-side superior temporal lines approach one another at midline. Its skull differs from a human skull in having more pronounced brows, thicker bones and a far smaller cranial capacity (. In humans, who have large brains (and hence large cranial vaults) relative to their body size, the temporal muscles occupy a position on the lateral walls of the cranial vault, and extend only about halfway up the vault surface. Disclaimer: AAAS and EurekAlert are not responsible for the accuracy of news releases posted to. The crest provides a surface for the attachment of the large chewing muscle, temporalis. ![]() Sagittal crests are rare in adult male chimpanzees and female gorillas, and are unknown in female chimpanzees, female orangutans, and humans and bonobos of both sexes (and are also absent in juveniles of all species). ![]() Gorillas move around by knuckle-walking, although they sometimes walk upright for short distances, typically while carrying food or in defensive situations. The brain size of gorillas averages 500 cc, but males, being bigger, tend to have larger brains than females. Gorillas are ground-dwelling, predominantly herbivorous apes that inhabit the forests of central Sub-Saharan Africa. Males grow considerably larger than females. Adult males also have a prominent sagittal crest. Gorillas are the largest living primates. The sagittal crest is a prominent ridge of bone that projects superiorly (upwards) from the cranial vault along its midline, most commonly seen in adult male gorillas and orangutans. Gorilla facial structure is described as mandibular prognathism, that is, the mandible protrudes farther out than the maxilla. ![]()
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