Research press release





今回、John Nyakatura、Kamilo Meloたちの研究グループは、Orobates pabstiの化石を調べた。Orobatesは、約2億9000万年前に生息していた大型の草食四足動物で、羊膜類の近縁種だと考えられている。Orobatesの化石とそれに対応する足跡化石の照合が行われ、Orobatesの動作と歩様に関する知見が得られた。著者たちは、このOrobatesの化石と足跡の分析結果を現生の両生類種と爬虫類種(計4種)の測定結果と組み合わせることで、Orobatesのデジタル復元を行い、ロボットシミュレーション(「OroBOT」と命名)を構築し、これを用いて歩行様式に関する仮説の妥当性と有効性を調べた。


Insights from robotics and simulated skeletons indicate that prehistoric tetrapods (four-legged animals) learnt to walk more efficiently on land earlier than previously thought, reports a paper published in this week’s Nature. These findings suggest that the development of efficient locomotion on land preceded the evolution and diversification of amniotes (reptiles, birds, and mammals).

Various adaptations facilitated the tetrapods’ move from living in water to walking on land. One group, the amniotes, diversified rapidly and have been associated with the development of a more efficient, upright walk. However, the timing of the development of this more advanced locomotion has been uncertain.

John Nyakatura, Kamilo Melo, and colleagues studied fossils of Orobates pabsti, a large four-legged, plant-eating animal that lived around 290 million years ago and is believed to be closely related to the amniotes. Fossil remains of Orobates have been matched to corresponding preserved tracks, revealing insights into its movement and gait. Combining analyses of Orobates fossils and tracks with measurements of four living amphibian and reptile species, the authors created both a digital reconstruction of Orobates and a robotic simulation - dubbed the ‘OroBOT’ - that they use to explore the plausibility and effectiveness of potential walking styles.

The authors find that Orobates was probably capable of a more upright walking gait than has typically been associated with non-amniotic tetrapods. Advanced styles of locomotion may therefore have evolved earlier than previously thought, the authors suggest.

doi: 10.1038/s41586-018-0851-2

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