Foraging behavior of Chleuastochoerus （Suidae, Artiodactyla）： A case study of skull and mandible morpho-functional analysis

The skull and mandible of a Late Miocene fossil pig, Chleuastochoerus, are compared morphologically with those of extant pigs and peccaries, and subjected to a functional analysis. The presence of a rostral bone in the skull and relatively strong ros- tral muscles indicates that Chleuastochoerus possessed considerable digging ability, though the relatively narrow occipital surface and the shortness of the skull would have restricted the range of motion through which the skull could be swung. The distinctive pre-zygomatic plate and over-canine arch-niche may have played a role in protecting the skull and canines during digging. The massive masticatory muscles, reconstructed based on well-developed parietal and zygomatic crests, would have enabled the mouth to close quickly and contributed to moving the mandible both longitudinally and laterally. The configura- tion of the cranio-mandibular joint and its relatively high position show clearly that Chleuastochoerus was capable of both crushing and grinding movements during mastication. The comparatively simple structure of the crown surfaces of the cheek teeth suggests that the food of Chleuastochoerus may have been softer than that of extant suids. The diet of Chleuastochoerus is postulated to fall between those of true forest pigs and open habitat pigs, and the habitat of Chleuastochoerus to be relatively humid forest edge or nearby areas of open steppe.