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寒い冬は,エオセーン/オリゴセンの境界線での大量絶滅の可能性がある原因である
L C Ivany1, W P Patterson, K C Lohmann
1Department of Geological Sciences, University of Michigan, Ann Arbor 48109, USA. lcivany@syr.edu
Nature
|November 1, 2000
まとめ
エオセノ/オリゴセノの境界線は,主要な海洋絶滅を目撃しました. 平均気温の変化ではなく,冬の気温変動の増加が,この重要な野生動物の周回を促した可能性が高い.
科学分野:
- 古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは,古代気候学 (paleoclimatology) とは
- パレオントロジー・パレオントロジー
- マリン・バイオロジー マリン・バイオロジー
背景:
- エオセノ/オリゴセノ境界 (33.7万年前) は,ケノゾイク期の大規模な海洋無脊椎動物の絶滅と関連しています.
- 以前の仮説では,温暖なエオセンの気候から,より冷たいオリゴセンの気候への移行が示唆されていたが,気候再構築には支持する証拠が欠けていた.
- この期間にアメリカ湾岸沿岸平原では,高種の軟体動物 (90%以上) が生息していた.
研究 の 目的:
- エオセノ/オリゴセノ絶滅の気候的要因を調査する.
- 平均年間気温の変化が動物の周回を引き起こしたという仮説を検証するために.
- エオセン/オリゴセンの境界を越えて詳細な古気温を再構築する.
主な方法:
- 化石魚の耳石 (耳石) のアラゴニトの安定酸素同位体分析.
- 季節的な気温変動を解決するために,オトリスの増量マイクロサンプリング.
- 酸素同位体値を用いた古気温の再構築.
主要な成果:
- 平均オトリフ酸素同位体値は,境界を越えて年間平均気温の最小の変化を示した.
- 季節的な気温データは,冬の気温で約4°Cの著しい冷却を示した.
- これは,平均気温の変化ではなく,気温変動の増加を示唆しています.
結論:
- 温度変動の増大,特に寒い冬は,エオセン/オリゴセン時代の野生生物の転移の主な要因として提案されています.
- この発見は,平均年間気温の変化にのみ焦点を当てた以前の仮説に異議を唱えるものである.
- この研究は,過去の絶滅の出来事を理解するために季節的な気候変動を考慮することの重要性を強調しています.
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