Body size reduction in wild boar (Sus scrofa) from the late Pleistocene Maehira Fissure Site in Okinawa-jima Island, Japan, with relevance to human arrival

Late Pleistocene to Holocene terrestrial vertebrate fossils were excavated at a newly-found fossil locality, Maehira Fissure Site, Itoman City, Okinawa-jima Island, Ryukyu Archipelago, Japan. Location F1 in this site can be divided into three beds characterized by dominance of extinct deer (Cervus astylodon and Mutiacinae sp.), birds, and wild boar in ascending order. 14C dating indicated approximately 23–20 ka BP from a snail shell collected from the deer bed and a charcoal from the boar bed. It has been considered that deer and boar lived together in the Okinawa-jima Island. However, the results indicate that deer extinction occurred before wild boar increase. The molar teeth of the late Pleistocene boar excavated from Location F1 of this site were larger than those of the Holocene boar from Location F2. This is the first report to demonstrate that the molar size of late Pleistocene boar is larger than that of Holocene boar from the same site.