ジュラ紀の生態系における哺乳類の耳の進化と餌の適応に関する新しい証拠

Zhe-Xi Luo^1,2, Qing-Jin Meng³, David M Grossnickle²

¹Department of Organismal Biology and Anatomy, The University of Chicago, Chicago, Illinois 60637, USA.

Nature

|August 10, 2017

まとめ

ジュラ紀の哺乳類の化石は草食動物に独特の歯の適応を明らかにしていますこの発見により初期の哺乳類の進化と幹哺乳類の食事の多様性に関する理解が広がりました

科学分野:

古生物学
進化生物学
脊椎動物学

背景:

現代の哺乳類の祖先である幹哺乳類は,重要な生態学的多様性を示した.
最近の発見は,ジュラ紀アジアにおけるエレウテルドンチド (ハラミイダ亜群) の種が以前よりも豊富であることを示している.

研究の目的:

ジュラ紀のエレウテロドンチド哺乳類の化石について
ハラミヤダンの幹哺乳類の配置を支えるために系統遺伝分析を行う.
新しい化石の独特の解剖学的・機能的特徴を調査する

主な方法:

皮膚膜と下中耳を含む解剖学的特徴の化石発見と記述.
進化的関係を決定する系統遺伝分析
歯の閉塞と推測された食事の適応の機能分析

主要な成果:

化石化した皮膚膜を持つ新しいジュラ紀のエレウテルドンチド哺乳類の記述滑り能力を示唆する.
独特の下中耳の構造と長い切り口の置換パターンの特定
草食性の特異性 (穀食性または軟植物の組織) を示す新しい二重モルタル閉塞の発見.
系統遺伝学的な分析は,ハラミヤダンを幹哺乳類として支持している.

結論:

この新しい化石はジュラ紀の草食性幹哺乳類を表しています
エレウテロドンチドは,セリアの草食動物と進化的収束を示している.
これらの発見は,アンジオスペルムの優位性以前の哺乳類の早期の草食性および滑動性適応を強調しています.

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