An investigation on the evolutionary significance of molar and masticatory structure in early hominids and fossil hominoids
| Project/Area Number |
16405016
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 海外学術 |
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| Research Field |
Anthropology
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| Research Institution | The University of Tokyo |
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Principal Investigator |
SUWA Gen The University of Tokyo, The University Museum, Associate Professor, 総合研究博物館, 助教授 (50206596)
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| Co-Investigator(Kenkyū-buntansha) |
KONO Reiko T. National Science Museum, Department of Anthropology, Researcher, 人類研究部, 研究官 (30356266)
KAIFU Yousuke National Science Museum, Department of Anthropology, Researcher, 人類研究部, 研究官 (20280521)
KONDO Osamu The University of Tokyo, Graduate School of Biological Sciences, Associate Professor, 理学系研究科, 助教授 (40244347)
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| Project Period (FY) |
2004 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥13,300,000 (Direct Cost: ¥13,300,000)
Fiscal Year 2005: ¥4,200,000 (Direct Cost: ¥4,200,000)
Fiscal Year 2004: ¥9,100,000 (Direct Cost: ¥9,100,000)
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| Keywords | Enamel Thickness / Early Hominid / Hominoid / Fossil Taxa / Masticatory Structure / Molar / Microfocus X-ray CT scanning / Functional Morphology |
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| Research Abstract |
In the present study, we investigated a broad range of fossil hominid and hominoid specimens in order to contribute to the clarification of the phylogenetic relationships and morphological adaptations of the earliest hominid genera and species of the circum 6 to 4 million year time period. We conducted high resolution micro-CT analysis on selected specimens of Australopithecus and early Homo, systematically assessed enamel thickness on natural fracture surfaces of East African early Homo and Australopithecus species, and acquired micro-CT or natural fracture based data on selected Eurasian and African hominoid taxa. In particular, we successfully obtained 3-dimensionally based high resolution estimations of whole crown enamel volume and distributions with both 'robust' and 'non-robust' Australopithecus molars, from extensive segmentation routines of micro-CT data. Our analyses of these and previously acquired thickness data of the earliest pre-4 myr hominids included the assessment of 1) the extent to which section position and orientation affect linear thickness measures, 2) the relationship between 3-dimensional volumetric and 2-dimensional section-based linear thickness measures, and 3) a comparative analysis of the fossil hominid and hominoid molars based on these methodological considerations. Results suggested that 1)the earliest pre-4.2 myr hominids have enamel thinner than the Australopithecus species, 2) Au. anamensis have thicker enamel than in previous hominids, but an overall intermediate molar structure compared with Au.afarensis, 3)there appears to be an overall size-related increase in enamel thickness within Australopithecus species, and 4)previous characterization of Miocene hominoid enamel thickness may be biased by inadequate methodologies. We have also documented considerable individual variation within species, calling for the need to gather larger samples by combining both CT and section data within an integrated methodological framework.
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Report
(3 results)
Research Products
(18 results)
