The Supraorbital Torus: "A Most Remarkable Peculiarity" [and Comments and Replies]

  title={The Supraorbital Torus: "A Most Remarkable Peculiarity" [and Comments and Replies]},
  author={M D Russell and Tasman Brown and StanleyM. Garn and Fakhry Giris and Spencer Turkel and Mehmet Yaşar Işcan and Ordean J. Oyen and Burkhard Jacobshagen and Michael Pietrusewsky and G Philip Rightmire and Fred H. Smith and Christy G. Ii Turner and Srboljub Živanovi{\'c}},
  journal={Current Anthropology},
  pages={337 - 360}
The supraorbital torus is found only in some genera of the primate order. Because no muscles of consequence attach directly to it, it has been considered nonfunctional. However, invitro strain-gauge experiments demonstrate that when the anterior teeth are loaded, the supraorbital region acts as a bent beam, pulled downward on each end by masticatory muscle forces and pushed upward centrally by bite force. Clinical and experimental data indicate that in response to repeated dynamic bending… 

Masticatory-stress hypotheses and the supraorbital region of primates.

There is no good reason to believe that enlarged browridges in living and/or fossil primates are structural adaptations to counter intense masticatory forces.


It was found that the supraorbital region of Macaca fascicularis and Papio anubis is strained relatively little during mastication and incision, which indicates that in macaques and baboons there is much more supraorbitals bone than is needed to counter masticatory loads, which suggests that their brow-ridges could be considerably smaller yet still counter masticallyatory stress without structural failure.

Masticatory loading and bone adaptation in the supraorbital torus of developing macaques.

This work develops three micro-CT-based FEA models of M. fascicularis skulls ranging in dental age from deciduous to permanent dentitions and validated them against published experimental data to evaluate the hypothesis that strain energy density (SED) magnitudes are high in subadult individuals with resulting bone growth in the supraorbital torus.

Interspecific perspective on mechanical and nonmechanical models of primate circumorbital morphology.

  • M. Ravosa
  • Biology
    American journal of physical anthropology
  • 1991
It is suggested that since circumorbital structures (especially the browridges) are located the farthest away from the chewing apparatus, they are least affected by masticatory stresses.

Masticatory stress, orbital orientation and the evolution of the primate postorbital bar.

The visual predation hypothesis of primate origins is reformulate by incorporating in vivo and fossil data and thus offers new insights into major adaptive transformations in the primate skull.

Morphological relationship between the cranial and supraorbital regions in Homo sapiens.

In the sample of all crania, the neurocranial size more strongly influenced the morphological variation of the ST than of the GL, and sex influenced both of these structures the most, suggesting that sex may be the main factor (having an influence independent of the other traits) on the morphologists of theGL and ST.

Strain in the Galago facial skull

Although the strain‐direction data for the galago circumorbital region offer support for the occurrence of facial torsion, the low magnitude of these strains suggests that this loading pattern may not be an important determinant of circumorbitals morphology.

A finite element analysis of masticatory stress hypotheses.

Finite element analysis is used to examine the extent to which geometric models provide accurate strain predictions in the face and evaluate whether simple global loading regimes predict strains that approximate the craniofacial deformation pattern observed during mastication, and proposes that FE models replace simple cranial models when interpreting bone strain data and formulating hypotheses about cranioFacial biomechanics.



Tooth eruption and browridge formation.

  • M. D. Russell
  • Geology
    American journal of physical anthropology
  • 1982
A parallel test of the proposed Oyen, Walker, and Rice model on a cross-sectional sample of Australian Aboriginal juvenile crania showed no relation between tooth eruption and the supraorbital surface morphology thought to be indicative of active bone deposition.

Stress and strain in the mandibular symphysis of primates: a test of competing hypotheses.

  • W. Hylander
  • Biology
    American journal of physical anthropology
  • 1984
The data suggest that during the power stroke of mastication, the macaque symphysis is predominately sheared dorsoventrally and/or twisted about a transverse axis and bent by lateral transverse bending of the mandibular corpora.

Mechanical function as an influence on the structure and form of bone.

Rosette strain gauges were attached to the cranial and caudal aspects of the proximal half of the radius in eight skeletally mature female sheep and in younger animals the process of osteonal remodelling seemed further advanced in the cortex which was customarily subject to the larger deformation.

Dental attrition and degenerative arthritis of the temporomandibular joint.

Patterns of degenerative joint disease in the Aboriginals illustrated a break-down in the physiological adaptability of the masticatory system resulting from increased occlusal stress consequent upon progressive tooth wear.

Structure of bone in the skulls of Neanderthal fossils.

  • N. Tappen
  • Geography
    American journal of physical anthropology
  • 1973
Close inspection of surface bone in skulls of Neanderthal man reveals weathering cracks extensive enough in one specimen, La Chapelle-aux-Saints, to allow preliminary analysis of major patterns of

Cortical surface patterns in human and nonhuman primates

An analysis of skulls from several primate species shows that a “worm-track” surface pattern, first identified in the brow region in fossil adult hominids and subsequently in olive baboons,

Browridge structure and function in extant primates and Neanderthals

The structural characteristics of the supraorbital ridge in three extent primate species and fossil Neanderthals are described and periods of rapid appositional growth of the browridges by means of fine cancellous bone formation are temporally correlated with dental development and eruption sequences.

The vermiculate surface pattern in brow ridges of Australopithecines and other very ancient hominids

A convoluted surface pattern of fine ridges, pits, and grooves characterized the brow ridges of Australopithecines and other very ancient fossil hominids. This vermiculate configuration terminated

A possible mechanism of Wolff's law: trabecular microfractures.

Significant trabecular microfracture in various stages of healing was observed in cancellous bone from both human and rabbit tibias whose bone was caused to remodel by experimental loading, suggesting that this mechanism may be responsible for the remodelling of trabECular bone in response to stress.