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Takemura F.,Okinawa National College of Technology | Sakagami N.,Tokai University | Takahashi S.,Kagawa University | Ono R.,Tokai University | And 7 more authors.
IECON 2015 - 41st Annual Conference of the IEEE Industrial Electronics Society | Year: 2015

This paper presents an image-based position measurement of underwater objects using a low-cost maritime mobile robot with a monocular camera. Visual recognition of distant underwater objects is possible in the water with high transparency, for example, in the coastal sea area of Okinawa prefecture, Japan. In this paper, we apply the proposed method to estimate the position of an old anchor that is at a deep of 30 [m] and is estimated to be hundreds-of-years-old in an archaeological site in Ishigaki Island. We explain the measurement principle of the proposed method and the developed system. Moreover, we describe the experiment conducted off the coast of Ishigaki Island and show the experimental results of the proposed method. © 2015 IEEE.


Kaifu Y.,National Museum of Nature and Science | Kaifu Y.,University of Tokyo | Fujita M.,Okinawa Prefectural Museum and Art Museum
Quaternary International | Year: 2012

Human skeletal remains of Late Pleistocene ages are known from both continental and insular regions of East Asia. This paper critically reviews some of these, with the aim of clarifying what is known and what remain to be known about fossil evidence regarding the origins, dispersals, and morphological diversification of early modern humans in the area. The focus is on relatively well-dated and/or morphologically informative specimens, including those from Zhiren Cave in South China, Tianyuan Cave and Upper Cave in North China, Salkhit in East Mongolia, and Yamashita-cho Cave I and Minatogawa Fissure in Okinawa, Japan. Although uncertainties still remain in the chronology and morphological status of some of these specimens, this small sample of fossil specimens has the potential to significantly contribute to an understanding of the early population history in East Asia. Compatibility of the available fossil evidence with recent genetic evidence is also discussed. © 2011 Elsevier Ltd and INQUA.


Ono R.,Tokai University | Katagiri C.,Okinawa Prefectural Museum and Art Museum | Kan H.,Kyushu University | Nagao M.,Japan National Institute of Advanced Industrial Science and Technology | And 4 more authors.
International Journal of Nautical Archaeology | Year: 2016

The Yarabuoki underwater site contains seven iron grapnel anchors and Early Modern Okinawan ceramic jars and is dated to the 16th-19th centuries. The site lies at a depth of 12-32 m off the western coast of Ishigaki Island in Okinawa, Japan. Based on underwater archaeological and broadband multibeam surveys, as well as historical research of the artefacts and Early Modern Ryukyuan shipping, we discuss the possible anchor and vessel types in Ryukyu and Eastern Asia in Early Modern times. We also discuss the efficacy of low-cost ROV for assisting surveys in shallow-water environments and the value of educational programmes for promoting the management and conservation of underwater cultural heritage. © 2016 Nautical Archaeology Society.


Honda M.,University of Tsukuba | Matsui M.,Kyoto University | Tominaga A.,University of Ryukyus | Ota H.,University of Hyogo | Tanaka S.,Okinawa Prefectural Museum and Art Museum
Molecular Phylogenetics and Evolution | Year: 2012

The Anderson's crocodile newt, Echinotriton andersoni, is considered a relic and endangered species distributed in the Central Ryukyus. To elucidate phylogenetic relationships and detailed genetic structures among populations, we analyzed variation in the mitochondrial cytochrome b gene. Results strongly support a primary dichotomy between populations from the Amami and Okinawa Island Groups with substantial genetic divergence, favoring a primary divergence between the two island groups. Within the latter, populations from the southern part of Okinawajima Island are shown to be more closely related to those from Tokashikijima Island than to those from the northern and central parts of Okinawajima. The prominent genetic divergence between the two island groups of the Central Ryukyus seems to have initiated in the Miocene, i.e., prior to formation of the strait that has consistently separated these island groups since the Pleistocene. The ancestor of the southern Okinawajima-Tokashikijima is estimated to have migrated from the northern and central parts of Okinawajima into southern Okinawajima at the Pleistocene, and dispersed into Tokashikijima subsequently. © 2012 Elsevier Inc.


Sakagami N.,Tokai University | Takemura F.,Okinawa National College of Technology | Ono R.,Tokai University | Katagiri C.,Okinawa Prefectural Museum and Art Museum | And 2 more authors.
ICIIBMS 2015 - International Conference on Intelligent Informatics and Biomedical Sciences | Year: 2015

In this paper, we propose an observation support system of a Remotely Operated Vehicle (ROV) for underwater archaeology. In general, it is difficult for unskilled users to drive an ROV for underwater observation because a camera mounted on an ROV always moves due to external disturbances and objects easily move out of the field of view (FOV) of the camera. Once an object is out of the FOV, users cannot easily find out it again. The observation support system is used to help unskilled users to drive an ROV. To realize the proposed system, object detection based on image processing is a key component. We apply the SURF (Speeded Up Robust Features) algorithm to detect archaeological objects, and investigate the performance of the algorithm using video images recorded by our ROV in an underwater archaeological site. © 2015 IEEE.


Fujitaa M.,Okinawa Prefectural Museum and Art Museum | Yamasaki S.,Okinawa Prefectural Museum and Art Museum | Katagiri C.,Okinawa Prefectural Museum and Art Museum | Oshiro I.,Okinawa Ishi No Kai | And 16 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2016

Maritime adaptation was one of the essential factors that enabled modern humans to disperse all over the world. However, geographic distribution of early maritime technology during the Late Pleistocene remains unclear. At this time, the Indonesian Archipelago and eastern New Guinea stand as the sole, well-recognized area for secure Pleistocene evidence of repeated ocean crossings and advanced fishing technology. The incomplete archeological records also make it difficult to know whether modern humans could sustain their life on a resource-poor, small oceanic island for extended periods with Paleolithic technology. We here report evidence from a limestone cave site on Okinawa Island, Japan, of successive occupation that extends back to 35,000-30,000 y ago. Well-stratified strata at the Sakitari Cave site yielded a rich assemblage of seashell artifacts, including formally shaped tools, beads, and the world's oldest fishhooks. These are accompanied by seasonally exploited food residue. The persistent occupation on this relatively small, geographically isolated island, as well as the appearance of Paleolithic sites on nearby islands by 30,000 y ago, suggest wider distribution of successful maritime adaptations than previously recognized, spanning the lower to midlatitude areas in the western Pacific coastal region. © 2016, National Academy of Sciences. All rights reserved.


Kubo M.O.,University of Tokyo | Yamada E.,Graduate University for Advanced Studies | Fujita M.,Okinawa Prefectural Museum and Art Museum | Oshiro I.,Okinawa ishi no kai
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2015

The Ryukyu Islands (Amami Islands, Okinawa Islands, and Sakishima Islands) form an island arch situated at the southern end of the Japanese archipelago. In this area, numerous fossiliferous localities have been estimated to date from the end of the Pleistocene, which have yielded abundant vertebrate fossil remains. Among the excavated fossils of terrestrial vertebrates, two extinct deer species, Cervus astylodon and Dicrocerus sp., are representative of the Late Pleistocene fauna of the Okinawa Islands. However, their ecological characteristics have been largely unknown to date. In the present study, we reconstructed the paleoecology of the deer species using mesowear and stable isotope analyses of tooth remains excavated from the Hananda-Gama Cave, Okinawa Island. Mesowear analysis estimates the properties of consumed food from the facet development of ungulate cheek teeth, with more abrasive diets (i.e., grass) resulting in more rounded cusps with a lower profile. Carbon isotopic composition (δ13C) reflects relative contribution of C3 (woody and most herbaceous plants) and C4 (grass growing in temperate to tropical regions) plants in diets, with the former showing lower δ13C values. Both extinct deer had sharp cusps with high profiles, which implied a significant amount of browse in diets. Our stable isotope analysis corroborated this: δ13C values were in the range of extant C3 feeders. Species ranges overlapped each other; however, C. astylodon had a wider range into the higher δ13C value range than Dicrocerus sp., which implied dietary niche differentiation between the two species. The dominance of C3 browse in their diet supports a hypothesis that hypsodont molar of C. astylodon was not an adaptive response to abrasive and wear-induced diet but correlated evolution with its elongated longevity, which was considered to be up to 26years of age. © 2015 Elsevier B.V.


Fukase H.,Hokkaido University | Wakebe T.,Nagasaki University | Tsurumoto T.,Nagasaki University | Saiki K.,Nagasaki University | And 2 more authors.
American Journal of Physical Anthropology | Year: 2012

Diversity of human body size and shape is often biogeographically interpreted in association with climatic conditions. According to Bergmann's and Allen's rules, populations in regions with a cold climate are expected to display an overall larger body and smaller/shorter extremities than those in warm/hot environments. In the present study, the skeletal limb size and proportions of prehistoric Jomon hunter-gatherers, who extensively inhabited subarctic to subtropical areas in the ancient Japanese archipelago, were examined to evaluate whether or not the inter-regional differences follow such ecogeographic patterns. Results showed that the Jomon intralimb proportions including relative distal limb lengths did not differ significantly among five regions from northern Hokkaido to the southern Okinawa Islands. This suggests a limited co-variability of the intralimb proportions with climate, particularly within genealogically close populations. In contrast, femoral head breadth (associated with body mass) and skeletal limb lengths were found to be significantly and positively correlated with latitude, suggesting a north-south geographical cline in the body size. This gradient therefore comprehensively conforms to Bergmann's rule, and may stem from multiple potential factors such as phylogenetic constraints, microevolutionary adaptation to climatic/geographic conditions during the Jomon period, and nutritional and physiological response during ontogeny. Specifically, the remarkably small-bodied Jomon in the Okinawa Islands can also be explained as an adjustment to subtropical and insular environments. Thus, the findings obtained in this study indicate that Jomon people, while maintaining fundamental intralimb proportions, displayed body size variation in concert with ambient surroundings. © 2012 Wiley Periodicals, Inc.


Fujita M.,Okinawa Prefectural Museum and Art Museum | Yamasaki S.,Okinawa Prefectural Museum and Art Museum | Sugawara H.,Educational Board of Urasoe City | Eda M.,Hokkaido University
Quaternary International | Year: 2014

Late Pleistocene to Holocene terrestrial vertebrate fossils were excavated at a newly-found fossil locality, Maehira Fissure Site, Itoman City, Okinawa-jima Island, Ryukyu Archipelago, Japan. Location F1 in this site can be divided into three beds characterized by dominance of extinct deer (Cervus astylodon and Mutiacinae sp.), birds, and wild boar in ascending order. 14C dating indicated approximately 23-20kaBP from a snail shell collected from the deer bed and a charcoal from the boar bed. It has been considered that deer and boar lived together in the Okinawa-jima Island. However, the results indicate that deer extinction occurred before wild boar increase. The molar teeth of the late Pleistocene boar excavated from Location F1 of this site were larger than those of the Holocene boar from Location F2. This is the first report to demonstrate that the molar size of late Pleistocene boar is larger than that of Holocene boar from the same site. © 2014 Elsevier Ltd and INQUA.


Gunji M.,University of Tokyo | Fujita M.,Okinawa Prefectural Museum and Art Museum | Higuchi H.,Keio University
Journal of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral Physiology | Year: 2013

Most birds show a characteristic head movement that consists of head stabilization and quick displacement. In this movement, which is analogous to saccadic eye movement in mammals, head stabilization plays an important role in stabilizing the retinal image. This head movement, called "head bobbing", is particularly pronounced during walking. Previous studies focusing on anatomical and behavioral features have pointed out that visual information is also important for diving birds, indicating its significance in the head movements of diving birds. In the present study, the kinematic and behavioral features of head bobbing in diving little grebes were described by motion analysis to identify the head movement in diving birds. The results showed that head-bobbing stroke (HBS) consisted of a thrust phase and a hold phase as is typical for head bobbing during walking birds. This suggests that HBS is related to visual stabilization under water. In HBS, grebes tended to dive with longer stroke length and smaller stroke frequency than in non-bobbing stroke. This suggests that the behavior, which is related to vision, affects the kinematic stroke parameters. This clarification of underwater head movement will help in our understanding not only of vision, but also of the kinematic strategy of diving birds. © 2013 Springer-Verlag Berlin Heidelberg.

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