南米の白亜紀末期の高度に特化した哺乳類の頭蓋骨
Guillermo W Rougier1, Sebastián Apesteguía, Leandro C Gaetano
1Department of Anatomical Sciences and Neurobiology, University of Louisville, Louisville, Kentucky 40202, USA. grougier@louisville.edu
Nature
|November 5, 2011
まとめ
新しい化石の発見は,南米の初期の哺乳類の多様性を明らかにしています. クレータ紀後期に由来するこれらの古代のドリオレステロイドは,ユニークな特徴を示し,化石記録の重要なギャップを埋める.
科学分野:
- パレオントロジー・パレオントロジー
- 哺乳類の進化について
- 中生期の哺乳類 メゾゾイク期の哺乳類
背景:
- ドリオレストイオイドは,現代の有袋類と胎盤類の祖先である絶滅した哺乳類群である.
- 以前は,ドライオレステロイドの化石は白亜紀後期以前には稀であり,その起源と多様化の理解を妨げていた.
- 南米のドリオレストイオイドは白亜紀後期までに固有であり多様であったが,初期の進化史は不明のままである.
研究 の 目的:
- 南米の初期の後期白期の最初の哺乳類の遺骸を記述する.
- ドライオルステロイドの起源と早期の多様化を調査する.
- 中世哺乳類の頭蓋骨の形態と生態学的多様性を記録する.
主な方法:
- 2つの部分的な頭蓋骨と,派生ドリオレステロイドのの記述.
- 単根モラーと双根プレモラーを含む独特の歯と頭蓋骨の特徴の分析.
- ラウラシアと他の中生期の哺乳類から知られているジュラ紀のドライオレステオイドと比較.
主要な成果:
- 新しい歯と頭蓋骨の特徴,長口と大きな犬を含む,派生ドリオレステロイドの発見.
- 新しい哺乳類は,ラウラシアのドライオレステオイドと結びつける特徴を展示し,ユニークな専門性を展示しています.
- これらの化石は,ゴンドワナの白亜紀の哺乳類の2番目の頭蓋骨を表しており,6,000万年の間隔を埋めています.
結論:
- この発見は,白亜期の南米のドライオレステロイド動物群の特有性と多様性を強調しています.
- 新しい標本では,トライボスフェン系以外の哺乳類の形態学的,生態学的多様性が予想外であることが明らかになった.
- この発見は,ゴンドワナの早期哺乳類の進化に関する私たちの理解を大幅に前進させています.
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