クレータ紀 の 化石 は,哺乳類 の 中耳 の 進化 の 新しい パターン を 明らか に し て い ます
Haibing Wang1,2, Jin Meng3, Yuanqing Wang4,5,6
1Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Beijing, China.
Nature
|November 29, 2019
まとめ
化石の証拠は,哺乳類の中耳の進化を明らかにしています. この研究は,他の哺乳類のグループから独立して,の骨を耳の構造に変換することを詳細に説明しています.
科学分野:
- 古生物学
- 進化生物学
- 哺乳類の進化
背景:
- 哺乳類の中耳の進化は重要な研究分野であり,進化史の再考を示唆する理論がある.
- 以前の研究では 哺乳類の耳の骨に の要素が変化した例が複数あったことが示されました
- 歯後の要素が歯骨から離れるという点については,理解のギャップがあった.
研究 の 目的:
- エオバタリドの多胞体哺乳類の 中央耳の構造を調べる
- の骨が中耳の骨に 変化する過程を明らかにするためです
- アロテリアにおける中耳の進化の遺伝的独立性を決定する.
主な方法:
- エオバタリドの多胞体哺乳類の保存状態の良い化石の分析
- 歯の後部と歯骨との接点の詳細な検査
- 異なる哺乳類のクラードにおける中耳の進化を比較するための系統遺伝分析.
主要な成果:
- エオバタリドの標本には断片的な哺乳類の中耳が確認された.
- サラングラ骨はマレウスに変形し,ステープとインカスの間の接触は制限された.
- マルレウス・インカスの関節は,哺乳類の形では二分型の配置 (アブティングまたは相互接続) を表しています.
- 系統遺伝学的分析は,アロテリアにおける哺乳類の中耳の独立した獲得を示しています.
結論:
- アロテリアにおける哺乳類の中耳の進化は,モノトレームとテリアとは独立していた.
- アロテリアの関節の共進化は 独特の関節の噛みしめを容易にした.
- 栄養装置の機能的な要求は,アロテリアの聴覚系の進化を促したのかもしれない.
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