まとめ
化石化した水母のような生物であるDipleurozoaが北米で発見され,その既知の範囲を拡大しました. これらの化石は,クラスがカンブリア下期から下シルウリア期まで存在していたことを示しています.
科学分野:
- パレオントロジー・パレオントロジー
- 進化生物学の進化生物学について
- マリン・バイオロジー マリン・バイオロジー
背景:
- 双方向対称性を示すコエレンテラタの化石は,以前オーストラリアで発見されていた.
- これらのユニークな化石は,ハリントンとムーアによって新しいクラスであるDipleurozoaとして分類されました.
- クラスDipleurozoaは,オーストラリア以外では以前報告されていませんでした.
研究 の 目的:
- Shawangunk (Tuscarora) 形成から新たに発見されたDipleurozoa標本について説明します.
- クラスDipleurozoaのストラティグラフィックと地理的な範囲を決定する.
- クラスDipleurozoa.内の新しい種と新しい属を確立する.
主な方法:
- 化石化した遺骸の古生物学的な発掘と分析.
- 化石を含む岩層の年齢を判別するためのストラティグラフィック分析.
- 比較形態学は,物理的特徴に基づいて新しい種や属を識別する.
主要な成果:
- 最近,ペンシルベニア州デラウェア・ウォーター・ギャップのシャワングンク (トゥスカロラ) 群で,多くのディプルロゾアエ種が発見されました.
- 新しい Dipleurozoa の属に属する3つの新しい種が特定されました.
- この発見は,Dipleurozoaの化石が,下カンブリア期から下シルウリア期の層に及ぶことを示唆している.
結論:
- クラスDipleurozoaは,これまで知られていたよりも広い地理的分布を有し,北米東部まで広がっています.
- ディプルロゾアの層構造の範囲は,下カンブリア期から少なくとも下シルリア期まで広がることが確認されています.
- この発見は,初期の海洋無脊椎動物の進化と古生物学地理学の理解を大幅に高めています.
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