Changes in limb posture with body size in sprawling quadrupeds: implications for the evolution of body size

• Project/Area Number: 22KJ1506
• Project/Area Number (Other): 19J00701 (2019-2022)
• Research Category: Grant-in-Aid for JSPS Fellows
• Allocation Type: Multi-year Fund (2023); Single-year Grants (2019-2022)
• Section: 国内
• Review Section: Basic Section 17050:Biogeosciences-related
• Research Institution: Nagoya University
• Principal Investigator: 飯島 正也 名古屋大学, 名古屋大学博物館, 特別研究員(CPD)
• Project Period (FY): 2023-03-08 – 2024-03-31
• Project Status: Completed (Fiscal Year 2023)
• Budget Amount: ¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000); Fiscal Year 2023: ¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000); Fiscal Year 2021: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000); Fiscal Year 2020: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000); Fiscal Year 2019: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
• Keywords: ワニ類 / 体サイズ / 歩行 / 進化 / バイオメカニクス / ロコモーション / モデリング / 骨ひずみ

Outline of Research at the Start

アメリカン・アリゲーターをモデルとして，這歩き→直立姿勢進化のバイオメカニクスを研究した．這歩き動物における姿勢と体サイズの関連性を探るため，幼体～成体を用いて，四肢キネマティクス，床反力，骨ひずみを比較した．直立型の哺乳類では，大型化に伴い，四肢が屈曲→伸展姿勢へシフトするが，這歩き型のアリゲーターでも同様の姿勢シフトがあることを示した．また，這歩き時の骨ひずみは体サイズに比例し増加することから，大型個体は，直立気味の姿勢をとり骨ひずみを緩和している可能性が高い．これらの結果は，哺乳類における屈曲→伸展姿勢と，爬虫類における這歩き→直立姿勢のパラダイムが同様に体サイズ依存であることを示した．

Outline of Annual Research Achievements

2023年4月から12月まで、英国王立獣医大学を拠点に，アメリカンアリゲーターの運動解析に取組んだ。前年度に収集した歩行時の前肢の筋電データを解析し、肩・上腕の9つの筋肉の活動パターンを明らかにした。また、前肢の姿勢と肩の内転筋の活動量に相関があることを発見し、姿勢と筋活動の進化について議論した。これらの結果は、2024年1月にJournal of Anatomy誌に掲載された。
英国滞在中には、アリゲーターの後肢の筋骨格モデルを修正し、歩行モデリングも行った。静的シュミレーションを使用して各筋の活動量を推定し、関節反力やセグメントの慣性特性データを入力し、四肢骨の骨幹部分にかかるストレスを推定した。その結果、アリゲーターでは大型個体ほど四肢骨のストレスが増大し、歩行能力が制限される可能性があることが示唆された。これらの結果をさらに分析し、検証を進め、論文化を目指している。
また、2023年10月には、北インドにて、インドガビアルの運動解析も行った。四肢のキネマティクスや床反力の測定を行い、インドガビアルにみられる特異的な歩行と骨格形態の関連を調査し、ロコモーション進化の解明に役立てることを目指している。
5年間の研究を通して、アリゲーターの幼体～成体を用いて、四肢キネマティクス測定と骨ひずみ測定を計画通りに進めることができた。また、当初予定していなかった前肢筋の筋電計測や、3D筋骨格モデルの作成及び歩行モデリングも行うことができた。

Research Products

• [Journal Article] Forelimb muscle activation patterns in American alligators: Insights into the evolution of limb posture and powered flight in archosaurs (2024)
  • Author(s): Iijima Masaya、Mayerl Christopher J.、Munteanu V. David、Blob Richard W.
  • Journal Title: Journal of Anatomy Volume: 244 Issue: 6 Pages: 943-958
  • DOI: 10.1111/joa.14011
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] A new hupehsuchian (Reptilia: Ichthyosauromorpha) from the Lower Triassic of South China with implications for the evolution of polydactyly (2023)
  • Author(s): Qiao Yu、Motani Ryosuke、Iijima Masaya、Liu Jun
  • Journal Title: Journal of Vertebrate Paleontology Volume: 43 Issue: 2
  • DOI: 10.1080/02724634.2023.2279530
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Scaling of Gait, Limb Posture, Forces, and Inertial Properties in Terrestrial Locomotion of American Alligators Across a Thousand-Fold Increase in Body Mass (2023)
  • Author(s): Iijima Masaya、Darlington Jim、Munteanu V David、Vliet Kent A、Blob Richard W
  • Journal Title: Integrative And Comparative Biology Volume: 63 Issue: 3 Pages: 664-680
  • DOI: 10.1093/icb/icad056
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Anatomy informs geology: hydrodynamic dispersal of alligator bones, with implications for taphonomic interpretations of fossil deposits of crocodylians (2022)
  • Author(s): Blob, R., Espinoza, I. Z. G., Iijima, M.
  • Journal Title: The Anatomical Record Volume: ー Issue: 7 Pages: 1618-1630
  • DOI: 10.1002/ar.25003
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Controlled feeding experiments with juvenile alligators reveal microscopic dental wear texture patterns associated with hard-object feeding (2022)
  • Author(s): Winkler Daniela E.、Iijima Masaya、Blob Richard W.、Kubo Tai、Kubo Mugino O.
  • Journal Title: Frontiers in Ecology and Evolution Volume: 10 Pages: 957725-957725
  • DOI: 10.3389/fevo.2022.957725
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] A globally distributed durophagous marine reptile clade supports the rapid recovery of pelagic ecosystems after the Permo-Triassic mass extinction (2022)
  • Author(s): Qiao, Y., Liu, J., Wolniewicz, A. S., Iijima, M., Shen, Y., Wintrich, T., Qiang, L., Sander, P. M.
  • Journal Title: Communications Biology Volume: 5 Issue: 1 Pages: 1242-1242
  • DOI: 10.1038/s42003-022-04162-6
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] An intermediate crocodylian linking two extant gharials from the Bronze Age of China and its human-induced extinction (2022)
  • Author(s): Iijima, M., Qiao, Y., Lin, W., Peng, Y., Yoneda, M., Liu, J.
  • Journal Title: Proceedings of the Royal Society B: Biological Sciences Volume: 289 Issue: 1970 Pages: 20220085-20220085
  • DOI: 10.1098/rspb.2022.0085
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Ontogenetic changes in limb posture, kinematics, forces and joint moments in American alligators (Alligator mississippiensis) (2021)
  • Author(s): Iijima, M., Munteanu, V.D., Elsey, R.M., Blob, R.W.
  • Journal Title: Journal of Experimental Biology Volume: 224 Issue: 23 Pages: 1-14
  • DOI: 10.1242/jeb.242990
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Function of the crocodilian anterior cruciate ligaments (2021)
  • Author(s): Suzuki, D., Yamakawa, S., Iijima, M., Fujie, H.
  • Journal Title: Journal of Morphology Volume: 282 Issue: 10 Pages: 1514-1522
  • DOI: 10.1002/jmor.21401
  • Peer Reviewed
• [Journal Article] Intervertebral joint polarity reversions in extant and extinct crocodylians (2021)
  • Author(s): Iijima Masaya、Kubo Tai
  • Journal Title: Acta Zoologica Volume: 102 Issue: 4 Pages: 386-393
  • DOI: 10.1111/azo.12346
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Taxonomic overview of Neogene crocodylians in Myanmar (2021)
  • Author(s): Iijima, M., Takai, M., Nishioka, Y., Thaung-Htike, Zin-Maung-Maung-Thein, Egi, N., Kusuhashi, N., Tsubamoto, T., Kono, R., Hirayama, R.
  • Journal Title: Journal of Vertebrate Paleontology Volume: e1879100 Issue: 6 Pages: 1-17
  • DOI: 10.1080/02724634.2021.1879100
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Vertebrae-based body length estimation in crocodylians and its implication for sexual maturity and the maximum sizes (2020)
  • Author(s): Iijima, M., Kubo, T.
  • Journal Title: Integrative Organismal Biology Volume: obaa042 Issue: 1 Pages: 1-21
  • DOI: 10.1093/iob/obaa042
  • Peer Reviewed / Open Access
• [Journal Article] The largest hupehsuchian (Reptilia, Ichthyosauromorpha) from the Lower Triassic of south China indicates early establishment of high predation pressure after the Permo-Triassic Mass Extinction (2020)
  • Author(s): Qiao, Y., Iijima, M., Liu, J.
  • Journal Title: Journal of Vertebrate Paleontology Volume: － Issue: 5 Pages: e1719122-e1719122
  • DOI: 10.1080/02724634.2019.1719122
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Comparative morphology of presacral vertebrae in extant crocodylians: taxonomic, functional and ecological implications (2019)
  • Author(s): Iijima Masaya、Kubo Tai
  • Journal Title: Zoological Journal of the Linnean Society Volume: 印刷中
  • DOI: 10.1093/zoolinnean/zly096
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Allometric growth of limb and body proportions in crocodylians (2019)
  • Author(s): Iijima M.、Kubo T.
  • Journal Title: Journal of Zoology Volume: 309 Issue: 3 Pages: 200-211
  • DOI: 10.1111/jzo.12714
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] The Muensterelloidea - Phylogeny and Character evolution of Mesozoic stem octopods (2019)
  • Author(s): Fuchs, D., Iba, Y., Heyng, A., Iijima, M., Klug, C., Larson, N., Schweigert, G.
  • Journal Title: Papers in Palaeontology Volume: 6 Issue: 1 Pages: 31-92
  • DOI: 10.1002/spp2.1254
  • Peer Reviewed / Int'l Joint Research
• [Journal Article] Mosaic nature in the skeleton of East Asian crocodylians fills the morphological gap between “Tomistominae” and Gavialinae (2019)
  • Author(s): Iijima Masaya、Kobayashi Yoshitsugu
  • Journal Title: Cladistics Volume: 35 Issue: 6 Pages: 623-632
  • DOI: 10.1111/cla.12372
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Journal Article] Discovery of a crocodyliform tooth from the upper Eocene Ergilin Dzo Formation, Mongolia (2019)
  • Author(s): Iijima Masaya、Tsubamoto Takehisa、Tsogtbaatar Khishigjav、Chinzorig Tsogtbaatar、Baasankhuu Soyol
  • Journal Title: Acta Palaeontologica Polonica Volume: 64 Pages: 775-778
  • DOI: 10.4202/app.00633.2019
  • Peer Reviewed / Open Access / Int'l Joint Research
• [Presentation] Modeling hindlimb muscle activation in walking alligators across limb posture and body size (2024)
  • Author(s): Iijima Masaya、Blob Richard W、Hutchinson John R
  • Organizer: Society for Integrative and Comparative Biology Annual Meeting
  • Int'l Joint Research
• [Presentation] Terrestrial locomotion of American alligators across body size ranging three orders of magnitude (2023)
  • Author(s): Iijima, M., Darlington, J, Vliet, K. A., K. M., Blob, R. W.
  • Organizer: Society for Integrative and Comparative Biology Annual Meeting, Austin, Texas
  • Int'l Joint Research
• [Presentation] In-vivo limb bone strain during terrestrial locomotion in American alligators across body size and limb posture (2022)
  • Author(s): Iijima, M., Munteanu, V. D., Elsey, R. M., Blob, R. M.
  • Organizer: Society for Integrative and Comparative Biology Virtual Annual Meeting
  • Int'l Joint Research
• [Presentation] Ontogenetic changes in limb kinematics, forces, and joint moments in American alligators (2021)
  • Author(s): Iijima, M., Munteanu, V. D., Kinsey, C. T., Elsey, R. M., Blob, R. M.
  • Organizer: Society for Integrative and Comparative Biology Virtual Annual Meeting
  • Int'l Joint Research
• [Presentation] Locomotor mechanics of juvenile alligators reveals ontogenetic changes in the roles of the fore- and hindlimbs (2020)
  • Author(s): Iijima, M., Munteanu, V. D., Diamond, K. M., Blob, R. W.
  • Organizer: Society for Integrative and Comparative Biology Annual Meeting, Austin, Texas
  • Int'l Joint Research
• [Presentation] 系統比較法によるワニ類の骨格進化様式の解明 (2020)
  • Author(s): 飯島正也
  • Organizer: 日本古生物学会 2020年例会
  • Invited