TY - JOUR
T1 - 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
AU - Takahashi, Akio
AU - Hirayama, Ren
AU - Otsuka, Hiroyuki
N1 - Funding Information:
We are grateful to T. Watabe and D. Hayakawa (Wan Park Kochi Animal Land, Kochi), E. Dondorp and J. de Vos (Naturalis Biodiversity Center, Leiden), and E. Setiyabudi (Geology Museum, Bandung) for allowing access to turtle skeletal specimens in their care. We also thank C. R. Crumly (University of California Press) for allowing access to his doctoral dissertation and H. Ota and T. Ikeda (University of Hyogo and Museum of Nature and Human Activities, Hyogo) and M. Natori (Okayama University of Science) for helpful comments. We are indebted to Y. Yasukawa and T. Otani (Takada Reptiles and Wildlife Research Institute, Okinawa), K. Kawaguchi (Kobe City, Hyogo), and R. Atsumi (Izoo, Shizuoka) who kindly offered us valuable specimens of extant testudinid turtles. We are also indebted to the late S. Oyama, the late C. Kishaba, S. Oyama, and M. Oyama (Naha City, Okinawa) for helping H.O. with field survey. The early version of the present paper was greatly improved with critical reviewing by two referees, E. Vlachos (Museo Paleon-tológico Egidio Feruglio, Argentina) and J. Claude (Institut des Sciences de l’Evolution, Montpellier, France), and by the editor, J. Sterli (Museo Paleontológico Egidio Feruglio, Argentina). This study was partially supported by the JSPS KAKENHI Grant, number 15K07202 (to A. T.).
Publisher Copyright:
© 2018, © by the Society of Vertebrate Paleontology.
PY - 2018/3/4
Y1 - 2018/3/4
N2 - Manouria 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/UJVP Citation 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.
AB - Manouria 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/UJVP Citation 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.
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U2 - 10.1080/02724634.2017.1427594
DO - 10.1080/02724634.2017.1427594
M3 - Article
AN - SCOPUS:85045029193
SN - 0272-4634
VL - 38
JO - Journal of Vertebrate Paleontology
JF - Journal of Vertebrate Paleontology
IS - 2
M1 - e1427594
ER -