Anthropological Concept
The size of these ridges varies also between different species of primates, either living or fossil. The closest living relatives of humans, the great apes, have a relatively pronounced supraorbital ridge, which has also been called a frontal torus while in modern humans it is relatively reduced. The fossil record indicates that the supraorbital ridge in early hominins was reduced as the cranial vault grew and became positioned vertically, above the face.
Some paleoanthropologists distinguish between torus and ridge. In anatomy, a torus is a projecting shelf of bone. Fossil hominids, in this theory, have the frontal torus, but modern humans only have the ridge.
Read more about this topic: Supraorbital Ridge
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