RELATIVE POSITION AND EXTENT OF THE NASAL AND ORBITAL OPENINGS IN GORILLA, PAN AND THE HUMAN SPECIES FROM THE STUDY OF THEIR AREAS AND CENTERS OF AREA

In order to quantify the relative position and extent of the nasal and orbital openings in hominoid primates, a new methodology based on ima ge analysis was developed and applied to a series of 134 hominoid skul ls (52 Gorilla gorilla; 30 Pan troglodytes, 44 Homo sapiens, and, as c omparison material, 8 Pongo pygmaeus). The areas and the centres of ar ea of the orbital and nasal openings were determined automatically, Th e orbitonasal triangle connecting these three centres of area was then constructed. This triangle was used to quantify the elongation of the face, It was most elongated in Gorilla, shortest in the human species and intermediate in Pan; the elongation in Pongo was close to that in Gorilla. The proportions of the areas of the orbital and nasal openin gs in the face were related to the extent of the bony structures of th e midface and were thus used to quantify the facial robustness. A robu st face was demonstrated in Gorilla, but a gracile face in the human s pecies. Robusticity in Pun was intermediate.