Eastern Margin Of Asian Continent Research Articles

Systematic revision of Manouria oyamai (Testudines, Testudinidae), based on new material from the Upper Pleistocene of Okinawajima Island, the Ryukyu Archipelago, Japan, and its paleogeographic implications

ABSTRACTManouria oyamai, an extinct, endemic testudinid turtle known from the upper Pleistocene of the Ryukyu Archipelago, southwestern Japan, has been reviewed on the basis of new specimens. The new specimens consist of a skull, as well as the first records of the epiplastron and the pelvis, all of which were found in a late Pleistocene fissure-filling deposit on Okinawajima Island, the Central Ryukyus, Japan. The present material provided four new informative morphological characters for M. oyamai: the anterior epiplastral projection, the epiplastra lacking extensive overhanging lip, the wide and fan-shaped iliac blade, and the wide ischiadic plate. The results of morphological comparisons and phylogenetic analysis indicated that M. oyamai is sister to M. emys (occurring in Bangladesh, eastern India, Myanmar, Thailand, the Malay Peninsula, Sumatra, and Borneo), and that M. impressa (in southern China, Laos, Malaysia, Myanmar, Thailand, and Vietnam) is the basal-most taxon within Manouria. In addition, the extremely thin carapace observed in M. oyamai, which had been cited as one of three diagnostic characters of this species as well as a feature thought indicative of insular adaptation, is also present in M. impressa within this genus. The present observation therefore indicates that this character is not always attributable to insular adaptation. The results of this study along with the current paleogeographic hypothesis of the Ryukyu Archipelago suggest that M. oyamai had differentiated from an extinct ancestral species shared with M. emys on the eastern margin of Asian continent not later than the early Pleistocene.SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at www.tandfonline.com/UJVPCitation for this article: Takahashi, A., R. Hirayama, and H. Otsuka. 2018. Systematic revision of Manouria oyamai (Testudines, Testudinidae), based on new material from the Upper Pleistocene of Okinawajima Island, the Ryukyu Archipelago, Japan, and its paleogeographic implications. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2017.1427594.

Origins and drift histories of some microcontinents distributed in the eastern margin of Asian Continent( Geotectonic framework of eastern Asia before the opening of the Japan Sea)

Origins and drift histories of some microcontinents distributed in the eastern margin of Asian Continent( Geotectonic framework of eastern Asia before the opening of the Japan Sea)

Late Cretaceous ignimbrite flare-up in the eastern margin of Asian Continent: an example of western Chugoku caldera cluster

Late Cretaceous ignimbrite flare-up in the eastern margin of Asian Continent: an example of western Chugoku caldera cluster

Gravel bearing radiolaria as tracers for erosional events: a review of the status of recent research in SW Japan and Korea

The authors introduce a case study of research on the provenance of radiolaria-bearing gravels and clasts of the monomictic chert-pebble conglomerates in the Lower Cretaceous Monobegawa Group, a paralic molasse in the Outer Zone of Southwest Japan. Reconstruction of oceanic plate stratigraphy from gravels and clasts in monomictic chert-pebble conglomerates based on their lithology and radiolarian ages is possible and effective for the provenance research in the case of the Monobegawa Group. A review of provenance studies of radiolaria-bearing gravels in Mesozoic orogenic sediments in SW Japan and Korea is included. The paper concludes with the discussion of the erosional events of the Jurassic and pre-Jurassic accretionary complexes in SW Japan with reference to the Late Mesozoic geological history in the eastern margin of Asian continent.