トライボスフェニック哺乳類の二重起源
Z X Luo1, R L Cifelli, Z Kielan-Jaworowska
1Section of Vertebrate Paleontology, Carnegie Museum of Natural History, Pittsburgh, Pennsylvania 15213, USA.
Nature
|May 9, 2001
まとめ
哺乳類の進化に不可欠なトライボスフェニックの歯茎は,2回独立して進化した. これは,古代哺乳類におけるこれらの複雑な歯の単一の起源という考えに異議を唱える.
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
- 哺乳類の解剖学について
背景:
- 複合的なトライボスフェニックの歯茎は,袋類,胎盤類,およびその親類の特徴であり,それらの多様化の鍵であると信じられています.
- 近年,ゴンドワナ地域における古代の高度な哺乳類の発見は,トライボスフェニック哺乳類の伝統的なローラシア起源仮説に異議を唱えている.
- 以前の仮説では,トライボスフェニックの歯茎に単一の進化的起源が提案されていた.
研究 の 目的:
- 哺乳類におけるトライボスフェニックの歯茎の進化的起源と生物地理を調査する.
- 新しい化石の証拠に基づいて,トライボスフェニックのモラーを持つ哺乳類のモノフィルを再評価する.
主な方法:
- 新しく発見された化石分類を組み込んだ系統遺伝学的分析.
- モラー構造の形態測定分析. モラー構造の形態測定分析.
主要な成果:
- トライボスフェニックのモラーを持つ哺乳類は単一フィレティックではないので,複数の独立した起源を示している.
- トリボスフェニックの歯は,ジュラ紀/白亜紀初期に2回独立して進化した.
- australosphenidans (monotremesを含むGondwanan) とboreosphenidans (marsupialsと胎盤を含むLaurasian) の2つの異なるクラッドは,これらのモラーを別々に開発しました.
結論:
- 複雑なトライボスフェニクモラー構造は,異なる哺乳類の系統で収束的に進化した.
- この発見は,哺乳類の進化史と生物地理学的モデルの見直しを必要とする.
- 哺乳類の多様化には,異なる地理的起源における重要な歯科革新の独立した進化が含まれていました.
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