まとめ
北米とアフリカのジュラ紀初期陸地脊椎動物の化石は,新しい相関関係を明らかにしています. この発見は,トライアス紀・ジュラ紀の境界で大きな四足類の絶滅が起こった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
- ストラティグラフィー ストラティグラフィー
- 脊椎動物の進化について
背景:
- トライアス紀・ジュラ紀の境界は,伝統的にテトラポッドの大規模な絶滅の時期と考えられています.
- これまでの大陸間の岩層の相関は,この境界を定義するために使用されています.
- ニューアーク超群 (米国東部),グレン・キャニオン群 (米国南西),ストームバーグ群 (アフリカ南部) は,重要な化石を保持する構造です.
研究 の 目的:
- ニューアーク・スーパーグループ,グレン・キャニオン・グループ,ストームバーグ・グループの重要な地上の脊椎動物の化石集合の年齢を再評価する.
- これらの南半球と北半球の形成の間のより正確なクロノストラティグラフィック相関を確立するために.
- トライアス・ジュラスの境界で広範囲にわたる四足類絶滅の事象の仮説を検証する.
主な方法:
- 指定された地質グループ内の陸生脊椎動物の化石発生の分析.
- 既定の化石の範囲に基づいたバイオストラティグラフィック・デッティング.
- 化石の証拠を用いて,異なる大陸の地質層の相関.
主要な成果:
- 陸上の脊椎動物の化石は,ニューアーク超群の一部とグレンキャニオン群全体の年齢がジュラ紀初期であることを示しています.
- 南アフリカの上ストームバーグ群もジュラ紀初期と確認されています.
- これらの発見は,これらの岩の単位のための新しいクロノストラティグラフィックフレームワークを確立します.
結論:
- トライアス紀・ジュラ紀の境界で以前推論された広範囲にわたる四足類の絶滅は,不正確な相関の人工物である.
- 化石記録は,地上の脊椎動物がトライアス紀・ジュラ紀の境界を越えて,より徐々に移行したことを示している.
- この改訂された相関は,この重要な期間中の脊椎動物の進化のより堅実な理解を提供します.
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