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Necropsy-based Wild Fish Health Assessment
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恐竜の突然の絶滅: 最新の白亜紀,上部のグレート・プレーンズ,米国
P M Sheehan1, D E Fastovsky, R G Hoffmann
1Department of Geology, Milwaukee Public Museum, WI 53233, USA.
Science (New York, N.Y.)
|November 8, 1991
まとめ
ヘル・クリーク・フォーメーションの恐竜の多様性は,絶滅前の段階的な衰退を示さなかった. これは,ゆっくりとした衰退ではなく,おそらく小惑星の衝突によって引き起こされた突然の絶滅の出来事を示唆しています.
科学分野:
- パレオントロジー・パレオントロジー
- ストラティグラフィー ストラティグラフィー
- 生態学的多様性 生態学的多様性
背景:
- ヘル・クリーク・フォーメーションは,白亜紀の終わりの恐竜の生態系を理解するための重要な場所です.
- 以前の研究では,白亜紀・旧亜紀の絶滅前の恐竜の減少の性質について議論されてきた.
研究 の 目的:
- ヘル・クリーク・フォーメーションの3年間の恐竜の生態学的多様性の家族レベルのパターンを調査する.
- クレタセア期が終わる前に,恐竜の個体数が徐々に減少していたかどうかを判断するためです.
主な方法:
- ヘル・クリーク・フォーメーション (モンタナ州とノースダコタ州) で3年間のフィールド研究を行った.
- ストラティグラフィックの信頼性を確保するために,形成の3つの部門を雇いました.
- 同様の化石集合を比較することによって保存バイアスを修正しました.
- 大規模で,統計的に厳格な調査と収集手順を使用しました.
主要な成果:
- 恐竜の生態学的多様性の漸進的な減少に関する統計的に有意な証拠 (P <0.05) は見つかりませんでした.
- 恐竜の多様性のパターンは,形成内の異なる層図レベルで一貫したままでした.
結論:
- この発見は,恐竜が突然絶滅したという仮説を裏付けている.
- 小惑星の衝突など,地外での衝突は,観測された漸進的な衰退の欠如と一致しています.
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