The modern and Late Pleistocene terrestrial fauna of Miyako Jima and adjacent islands (the Miyako Islands) in the southern Ryukyu Islands, southwestern Japan, includes some endemic taxa or genetically unique populations that exclusively have closest allies in the more isolated Okinawa Jima and adjacent islands (the Okinawa Islands) than in the Yaeyama Islands, which are located southwest of the Miyako Islands with much narrower intervening straits. Those taxa or populations include representatives of lineages that have physiologically highly limited ability for over-sea dispersal and the Miyako Islands are currently separated from the Okinawa Islands by at least 300 km of open water; therefore, the formation of this phylogeographical pattern is perplexing. In this study, we review the late Cenozoic geology of the Miyako Islands, southern Okinawa Jima, the Okinawa–Miyako submarine plateau (OMSP; a plateau located between Okinawa Jima and Miyako Jima), and the Kerama gap, which is a depression between the OMSP and Okinawa Jima. We then consider the origin of the modern and Late Pleistocene terrestrial animals, including a number of non-volant vertebrates on the Miyako Islands. Finally, we propose a new hypothesis (the OMSP hypothesis) to explain the enigmatic composition of modern and Late Pleistocene terrestrial vertebrate fauna of the islands. Southern Okinawa Jima was uplifted and emerged after ca. 2 Ma and was temporarily connected to the OMSP, which is likely to have emerged earlier than southern Okinawa Jima, to form a large island extending from Okinawa Jima to the Miyako Islands with a NE–SW direction of ~ 400 km. Subsequently, Okinawa Jima became separated from the OMSP when the Ryukyu Group—which is composed of Quaternary reef and associated fore-reef and shelf deposits—began to accumulate around the island at 1.7–1.4 Ma. During the interval from 2.0 to 1.7–1.4 Ma, numerous terrestrial animals, including flightless vertebrates, extended their distribution to the OMSP. Although the Miyako Islands repeatedly underwent complete submergence during deposition of the main part of the Ryukyu Group (1.25–0.4 Ma), they were uplifted and emerged to become a land area after ca. 0.4 Ma. In contrast, the OMSP subsided after ca. 0.4 Ma and was almost completely submerged after 0.27 Ma. During ca. 0.4–0.27 Ma, terrestrial animals migrated from the OMSP to the Miyako Islands.

日本西南部琉球群岛南部的宫古岛和邻近岛屿（宫古群岛）的现代和晚更新世陆地动物群包括一些特有类群或遗传上独特的种群，它们在比八重山群岛更孤立的冲绳岛和邻近岛屿（冲绳群岛）中拥有最亲密的盟友，八重山群岛位于宫古群岛西南部，中间的海峡要窄得多。这些类群或种群包括生理上具有高度有限的海外扩散能力的谱系代表，宫古群岛目前与冲绳群岛相隔至少 300 公里的开阔水域；因此，这种系统发育地理学模式的形成是令人费解的。在这项研究中，我们回顾了宫古群岛的晚新生代地质情况，冲绳岛南部、冲绳宫古海底高原（OMSP；位于冲绳岛和宫古岛之间的高原）以及庆良间间隙（OMSP 和冲绳岛之间的洼地）。然后我们考虑现代和晚更新世陆地动物的起源，包括宫古群岛上的一些非飞行脊椎动物。最后，我们提出了一个新的假设（OMSP 假设）来解释现代和晚更新世陆地脊椎动物群的神秘组成。冲绳岛南部隆起并在大约 10 年后出现。2 Ma 并暂时与 OMSP 相连，OMSP 可能早于冲绳岛南部出现，形成一个从冲绳岛延伸到宫古群岛的大岛，东北-西南方向长约 400 公里。随后，当琉球群（由第四纪珊瑚礁和相关的前礁和陆架沉积物组成）在 1.7-1.4 Ma 开始在岛周围堆积时，冲绳岛与 OMSP 分离。在2.0到1.7-1.4Ma期间，许多陆生动物，包括不会飞的脊椎动物，将其分布范围扩展到了OMSP。虽然宫古群岛在琉球群主体沉积期间（1.25-0.4 Ma）多次经历完全淹没，但大约在 10 年后，宫古群岛被抬升并成为陆地区域。0.4马。相反，OMSP 在大约 10 年后消退。0.4Ma，0.27Ma后几乎完全被淹没。期间约。0.4–0.27Ma，陆生动物从OMSP迁徙到宫古群岛。