Study on the adaptive radiation and extinction of Quaternary terrestrial vertebrates of the Nansei Islands.

通过对琉球群岛的地层学研究和陆生脊椎动物化石的古生物学分析，对动物从大陆向邻近岛屿迁徙的历史和年代提供了有价值的线索和思考。迄今为止，已在该群岛划分出五个不同的地层级别，其中包括晚中新世至更新世最新的脊椎动物化石。地质学和古生物学数据表明，琉球群岛地区曾多次与亚洲大陆相连，每次陆地连接之后，都有陆地脊椎动物从大陆迁移。在这五个不同的地层级别中发现的化石组合中，第二层（早更新世）的化石组合已知出现在早更新世至中更新世琉球群下面的浅海沉积物中。他们被命名为今渡-赤俣组合，被认为是来自 关于我们 第二次陆缘连接时，既没有发现安徽省上新世最新的人字洞动物群，也没有发现四川省巫山人科动物群。这一组合可能是最古老的中新世后动物群，可能包括琉球群岛更新世特有陆生脊椎动物群的祖先。今守-赤俣组合中的脊椎动物中，鹿（= Cervus（Metacervulus））的原型与第三陆缘的其他移民如Dicrocerus？sp.和大陆龟（=Manouria Sp.）。另一种重要的陆生脊椎动物化石组合与琉球群内最新更新世的裂缝和洞穴沉积或同时代阶地沉积（4级）密切相关。这些组合被认为是在过去不同的陆地连接时期从亚洲大陆迁移到岛屿的混合动物群。这一层的陆生脊椎动物化石包括大型哺乳动物（鹿）和在更新世末灭绝的巨型陆龟。然而，包括哺乳动物、两栖动物和爬行动物在内的其他动物的后裔仍然生活在岛上，形成了具有岛屿特色的特有动物群。少

Results of the studies on the stratigraphic levels and the paleontological analysis of terrestrial vertebrates fossil in the Ryukyu islands furnish valuable clues and considerations as to the history and age of animal migration from the continent to its neighboring islands. To date, five diagnos-tically different stratigraphic levels containing Late Miocene to latest Pleistocene vertebrate fossils have been delineated in the islands. Geological and paleontological data suggest that the area of the Ryukyu Islands has been repeatedly connected to the Asiatic Continent and each land connection has been followed by migration of characteristic terrestrial vertebrates from the continent. Among the fossil assemblages found in these five different stratigraphic levels, those from Level 2 (Early Pleistocene) are known to occur in shallow marine deposits underlying the Early to Middle Pleistocene Ryukyu Group. They are named Imadomari-Akagimata assemblage and are considered to be immigrants from … More neither the latest Pliocene Renzidong fauna in Anhui Province nor the Wushan hominid fauna in Sichuan Province, both located in Central China, during the second land connection. This assemblage may be regarded as the oldest post-Miocene fauna and might include the ancestors of the Pleistocene fossil and living endemic terrestrial vertebrate faunas of the Ryukyu islands. Among the vertebrates in the Imadomari-Akagimata assemblage, the archetypal deer (= Cervus (Metacervulus) flourished in the islands during the Pleistocene, together with other immigrants of the third land connection such as Dicrocerus? sp. and large tortoise (=Manouria Sp.).Another important species of fossil assemblage of terrestrial vertebrates in the islands is closely associated with the latest Pleistocene fissure and cave deposits developed within the Ryukyu Group or coeval terrace deposits (Level 4). These assemblages are considered to be mixed faunas that migrated from the Asiatn mainland to the islands during different periods of land connection in the past. Terrestrial vertebrate fossils from this level include large mammal (deer) and giant land tortoises that became extinct at the end of the latest Pleistocene. However, decendants of other animals including mammals, amphibians and reptiles, are still living in the islands forming characteristic insular endemic fauna. Less