title: Geographical variation of skull morphology and its functional significances in the red-cheeked squirrel.
abstract: Skulls of the red-cheeked squirrel (Dremomys rufigenis) from various geographical locations: Malaysia (peninsular area), Vietnam (south district)-Laos, and Thailand (north district) were osteometrically examined. The skull size of the squirrels in the southern (Malaysia) population was fundamentally larger than that in the northern (Vietnam, Laos and Thailand) populations. The proportion indices indicated that the splanchnocranium was relatively longer in the Malaysia population, and that the interorbital space was narrower in Vietnam-Laos, and Thailand populations. We suggest that the long nose and laterally-oriented orbits in the skull may be better adapted for terrestrial-insectivorous life in the Malaysia population and the binocular sense facilitated by rostrally-oriented eyes contributes to the arboreal-fruit eating behavior in the two northern populations. The Malaysia population was clearly distinguished from the other populations by the principal component analysis. We suggest that the geographical barrier of the Isthmus of Kra influences the morphological variation of the skull among the squirrel populations.
authors.affiliation: Department of Zoology, National Science Museum, Tokyo, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Endo
authors.forename: Junpei
authors.initials: J
authors.lastname: Kimura
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Oshida
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Stafford
authors.forename: Worawut
authors.initials: W
authors.lastname: Rerkamnuaychoke
authors.forename: Takao
authors.initials: T
authors.lastname: Nishida
authors.forename: Motoki
authors.initials: M
authors.lastname: Sasaki
authors.forename: Akiko
authors.initials: A
authors.lastname: Hayashida
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Hayashi
mesh_terms: D000220:Adaptation, Biological; D000818:Animals; D001208:Asia; D001837:Body Weights and Measures; D005247:Feeding Behavior; D005260:Female; D005843:Geography; D008297:Male; D025341:Principal Component Analysis; D012589:Sciuridae / Q000033:anatomy & histology* / Q000502:physiology; D012886:Skull / Q000033:anatomy & histology* / Q000502:physiology