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A sagittal crest is a ridge of bone running lengthwise along the midline of the top of the skull (at the sagittal suture) of many mammalian and reptilian skulls, among others. The presence of this ridge of bone indicates that there are exceptionally strong jaw muscles. The sagittal crest serves primarily for attachment of the temporalis muscle ...
In the human skull, a sagittal keel, or sagittal torus, is a thickening of part or all of the midline of the frontal bone, or parietal bones where they meet along the sagittal suture, or on both bones. Sagittal keels differ from sagittal crests, which are found in some earlier hominins (notably the genus Paranthropus) and in a range of other ...
Roughness appears in the sagittal crest and its located further back by the nuchal crest of gorillas and apes. The KNM-ER 406 sagittal crest is situated near the frontal bone and the highest point of the sagittal crest is located more medially. The development of the robusticity comes from the anterior part of the temporals muscles.
The skulls of males have a well-defined sagittal crest on the midline of the skullcap and inflated cheek bones, which likely supported massive temporal muscles important in biting. The cheeks project so far from the face that, when in top-view, the nose appears to sit at the bottom of a concavity (a dished face).
Paranthropus had a massively built, tall and flat skull, with a prominent gorilla-like sagittal crest along the midline which anchored large temporalis muscles used in chewing. [32] Like other australopithecines, Paranthropus exhibited sexual dimorphism, with males notably larger than females.
The combination of a tall face, thick palate, and small braincase caused a highly defined sagittal crest on the midline of the skull. The only complete tooth crown of the specimen is the right third premolar, whose dimensions are well above the range of variation for P. robustus and on the upper end for P. boisei.
KNM-ER 406, the skull of a Paranthropus, brain volume estimated to 410 cm 3 with a visible sagittal crest and mild or intermediate post-orbital constriction but KNM-ER 37333, the skull of a Homo erectus, brain volume of 850 cm 3 with no visual sagittal crest and an almost not present or reduced post-orbital constriction. [4]
KNM-WT 17000 (also known as "The Black Skull") is a fossilized adult skull of the species Paranthropus aethiopicus. It was discovered in West Turkana , Kenya by Alan Walker in 1985. [ 1 ] Estimated to be 2.5 million years old, the fossil is an adult with an estimated cranial capacity of 410 cc. [ 1 ] [ 2 ]