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南米のジュラ紀の哺乳類
Oliver W M Rauhut1, Thomas Martin, Edgardo Ortiz-Jaureguizar
1Museo Paleontológico Egidio Feruglio, Fontana 140, 9100 Trelew, Argentina.
Nature
|March 15, 2002
まとめ
南アメリカから発見された新しいジュラ紀の哺乳類化石は,オーストラリアスフェニダの初期の多様化を明らかにしている. この発見は,ジュラ紀期における南半球の独特の哺乳類ファウナを強調しています.
科学分野:
- パレオントロジー・パレオントロジー
- 進化生物学の進化生物学について
- 哺乳類の進化について
背景:
- ジュラ紀は,早期哺乳類の進化と多様化にとって極めて重要です.
- ジュラ紀の哺乳類,特にゴンドワナランド (南の大陸) の化石記録は稀です.
- 以前の発見はタンザニア,マダガスカル,アルゼンチン (トラックウェイ) に限られていた.
研究 の 目的:
- 南アメリカから新しいジュラ紀哺乳類の化石が発見されたことを報告するためです.
- 化石の分類学および進化的意義を特定する.
- ゴンドワナランドにおける初期の哺乳類の分布と多様性を理解する.
主な方法:
- 哺乳類の歯 (下) の化石発見と分析.
- 地質年代測定法により,ジュラ紀中期から晩期を決定する.
- 既知の哺乳類群,特に Australosphenida との比較分析.
主要な成果:
- パタゴニアの歯科の化石は,南米初のジュラ紀哺乳類を表しています.
- この化石は,コンバージェントのトライボスフェニックの歯を持つゴンドワナ群であるAustralosphenidaに属しています.
- 証拠によると,オストラロスフェニダはジュラ紀が終わる前にゴンドワナランドに多様化し,広がった.
結論:
- この発見は,南半球におけるジュラ紀の哺乳類の既知の地理的範囲を拡大する.
- これは,Australosphenidaがゴンドワナランドで広く,多様であったという仮説を支持する.
- 南半球におけるジュラ紀の哺乳類の動物群は,北半球のものとは異なっていた.
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