An osteometrical study of the cranium and mandible of Ryukyu wild pig in Iriomote island.

We measured crania and mandibles of Ryuku wild pigs from Iriomote Island. Sex and age were determined by observation of lower teeth. From the present data, the growth pattern was established for some items. For several parts of the cranium and mandible, the relative growth coefficient was compared. The results obtained here are summarized as follows: (1) Although sexual dimorphism was already shown in the younger group, a significant difference in profile length and length from the angle was not seen in the adult group. (2) As the animal grew, the proportion of length to width became larger in the skull. (3) The visceral cranium grew more rapidly in length than the cerebral cranium. On the other hand, growth of the cerebral cranium contributed to width in cranial development. (4) The body of the mandible was shown to grow more rapidly in length than the ramus of the mandible. (5) The growth pattern of some items was related to that of their associated muscles. These basic data are expected to be compared with data from other population of the same subspecies and Japanese wild pig. The comparisons will contribute to the establishment of origin and phylogeny of this animal.