恐竜の成長パターンと鳥類の急速な成長率

G M Erickson¹, K C Rogers, S A Yerby

¹Department of Biological Science and College of Medicine, Florida State University, Tallahassee, Florida 32306-1100, USA. gerickson@bio.fsu.edu

Nature

|July 27, 2001

まとめ

恐竜はユニークな成長率を示し,爬虫類よりも速く加速したが,現代の鳥よりも遅かった. この加速した恐竜の成長率は鳥に受け継がれ,鳥の急速な成長はセロポッドの祖先から分岐した後に段階的に進化した.

科学分野:

パレオントロジー・パレオントロジー
発達生物学発達生物学について
進化生物学の進化生物学について

背景:

恐竜の成長パターンを理解することは,彼らの生物学と進化的関係を再構築する鍵です.
以前の研究では,恐竜が現代の爬虫類,哺乳類,鳥類と成長戦略を共有していたかどうか議論されていた.

研究の目的:

様々な種の恐竜の成長率を定量化して比較する.
急速な鳥類の成長率が恐竜の祖先から受け継いだのか,鳥類で独立して進化したのかを判断する.

主な方法:

恐竜の多様なグループの成長率の定量化.
成長パターンを体質との関係で特徴付けるための回帰分析.
恐竜の成長曲線と現在存在する脊椎動物 (爬虫類,哺乳類,鳥類) の成長曲線の比較.

主要な成果:

恐竜は,脊椎動物に共通するシグモイド型の成長曲線を示したが,独特の体質特異的な速度を示していた.
すべての恐竜は,現存する爬虫類と比較して,加速した成長を示した.
大きな恐竜は,エウテリア類の哺乳類や早熟期の鳥類に匹敵する成長率を達成し,巨大なサウロポッドは成長においてクジラに似ている.
非鳥類の恐竜は,他の鳥類の急速な成長率に達しなかった.

結論:

恐竜の成長は顕著で,爬虫類に比べて加速した速度で特徴付けられました.
鳥類の急速な成長率は,鳥類がセロポッド恐竜から分離した後に段階的に進化した.
恐竜の先駆者は,鳥の急速な成長の進化に寄与した可能性がある.

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