title: Lateral orbital rim; open or closed in mammals.
abstract: We tried to determine the relationship between the presence of the lateral orbital rim and shape of the skull in certain mammals. From the literature, 15 mammals with the orbit closed at the back by a bony bar (closed group) and 18 mammals with the orbit closed at the back without a bony bar (open group) were selected. Calculation of interorbital-zygomatic breadth ratio (IZR, interorbital breadth/zygomatic breadth) and nasal-skull ratio (NSR, length of nasals/greatest length of skull) was performed.IZR of the closed group (0.73 ± 0.27) was significantly greater than that of the open group (0.35 ± 0.63, P = 0.000). NSR of the closed group (0.32 ± 0.97) was significantly lower than that of the open group (0.41 ± 0.67, P = 0.023).The open group (primarily carnivores) showed a lower interorbital-zygomatic breadth ratio, and here both orbits were located in close proximity. Although this bony structural arrangement is favorable for stereoscopic vision, the total field of view particularly lateral vision becomes limited. It is our view that the opened lateral orbital rim compensates for the limited lateral vision.
authors.affiliation: Department of Plastic Surgery, and Center for Advanced Medical Education by BK21 project, Inha University School of Medicine, Incheon, Korea.
authors.forename: Kun
authors.initials: K
authors.lastname: Hwang
authors.forename: Sowhey
authors.initials: S
authors.lastname: Park
authors.forename: Dae Joong
authors.initials: DJ
authors.lastname: Kim
mesh_terms: D000818:Animals; D008322:Mammals / Q000033:anatomy & histology*; D009915:Orbit / Q000033:anatomy & histology*; D015050:Zygoma / Q000033:anatomy & histology*