ジュラ紀初期からの新しい哺乳類形態と哺乳類の特徴の進化
Z X Luo1, A W Crompton, A L Sun
1Section of Vertebrate Paleontology, Carnegie Museum of Natural History, Pittsburgh, PA 15213, USA. luoz@carnegiemuseums.org
Science (New York, N.Y.)
|May 26, 2001
まとめ
ジュラ紀初期の新しい化石は,これまで知られていたよりも4500万年前に重要な哺乳類の特徴を持つ初期の哺乳類の親類 (哺乳類型) を明らかにしています. この発見は,古代哺乳類における中耳や脳のような特徴の漸進的な進化を強調している.
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
- 脊椎動物の古生物学について
背景:
- 哺乳類は絶滅した集団で,哺乳類と密接に関連している.
- 中耳の骨が下から分離し,頭蓋骨が大きくなるなど,哺乳類の重要な特徴は,哺乳類の進化を理解するために極めて重要です.
- 初期の哺乳類の進化,特にこれらの特徴に関する化石記録は稀です.
研究 の 目的:
- 新しいジュラ紀初期哺乳類の化石を記述するために.
- その頭蓋骨と下の特徴の進化的重要性を決定するために.
- 重要な哺乳類のイノベーションのタイムラインと進化パターンを再評価する.
主な方法:
- 初期のジュラ紀 (シネムリアン) の堆積物からの化石の発見と発掘.
- 化石の頭蓋腔と下の比較解剖学的分析.
- 他の哺乳類と哺乳類との関係を推論するための系統遺伝学的な括弧.
主要な成果:
- 約1億9500万年前の新しい哺乳類の系統が特定されました.
- 化石には,頭蓋骨の穴が大きくなり,歯後の溝がなく,中耳の骨が下から分離していることを示している.
- これらの特徴は,これらの哺乳類の特徴の最も古い既知の発生を約4500万年前に後退させる.
結論:
- 中耳の骨と大脳皮の分離は,徐々に進化した可能性があり,相関している可能性があります.
- 哺乳類の重要な革新は,哺乳類の形態の中で徐々に進化し,現存する哺乳類群の多様化に先立ちました.
- 小さい体積 (2g) とより大きな哺乳類との共存は,初期の昆虫を食べる哺乳類の間で重要なトロフィック多様性を示唆しています.
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