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

琉球群岛陆生脊椎动物化石的地层层次和古生物分析结果，为研究大陆动物迁徙到邻近岛屿的历史和年代提供了有价值的线索和思考。到目前为止，在这些岛屿上已经划定了五个不同的成岩地层级别，包含了晚中新世到最新更新世的脊椎动物化石。地质和古生物数据表明，琉球群岛地区曾多次与亚洲大陆相连，每一次陆地连接都伴随着大陆特有的陆生脊椎动物的迁徙。在这五个不同地层中发现的化石组合中，2级(早更新世)的化石组合已知出现在早至中更新世琉球群下面的浅海沉积中。他们被命名为Imadomari-Akagimata组合，被认为是来自…的移民在第二次陆路连接期间，既没有安徽上新世的仁子洞动物群，也没有四川的巫山古人类动物群，它们都位于中国中部。这一组合可以被认为是最古老的后中新世动物群，可能包括更新世化石的祖先和琉球群岛现存的地方性陆生脊椎动物动物群。在Imadomari-Akagimata组合中的脊椎动物中，原型鹿(=Cervus(Metacerverus))与其他第三陆路连接的移民如Dmicrocerus？一起在更新世期间在这些岛屿上蓬勃发展。SP.另一种重要的陆生脊椎动物化石组合与琉球群或同时代阶地沉积(4级)中发育的最新更新世裂隙和洞穴沉积密切相关。这些组合被认为是在过去不同的陆路连接时期从亚洲大陆迁移到岛屿的混合动物群。这一级别的陆生脊椎动物化石包括大型哺乳动物(鹿)和在最新更新世末期灭绝的巨型陆龟。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代仍然生活在这些岛屿上，形成了独特的岛屿特有动物群。较少

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