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最も原始的なオステイチアンの脳箱?
A M Basden1, G C Young, M I Coates
1Centre for Ecostratigraphy and Palaeobiology, Department of Earth and Planetary Sciences, Macquarie University, New South Wales, Australia. abasden@laurel.ocs.mq.edu.au
Nature
|January 26, 2000
まとめ
オーストラリアで4億年前の化石の脳蓋が発見されたことで,初期の骨魚 (オステイクシアン) の原始的な特徴が明らかになった. この発見は,線羽魚 (アクチノプテリジアン) およびすべての現代オステイクシアン群の進化的起源に関する新しい洞察を提供します.
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
- 脊椎動物学 脊椎動物学
背景:
- オステイチア (骨魚) は,生きている脊椎動物の中で最も多様な群れであるが,その進化的起源は不明である.
- 最も成功した脊椎動物群であるアクティノプテリジアン (射線の魚) は,シルウリア後期に化石記録に初めて登場したが,デボニア後期以前にはほとんど理解されていない.
研究 の 目的:
- "最も古く,最も原始的なアクチノプテリジアン類のオステイクチアンの脳細胞の発見を報告する.
- 現代のオステイクシアン群の進化的放射線に近い解剖学的条件に関する新しい洞察を提供するため.
主な方法:
- オーストラリア南東部の4億年前の石灰岩から化石化したオステイクチアンの脳蓋の発見と分析.
- Psarolepis.pis.などの他の初期の骨質動物との比較解剖学的分析.
主要な成果:
- アクチノプテリジアン類のオステイクシアン類の最も古い脳殻が発見され,その年代は4億年前にさかのぼる.
- この標本には,以前は文書化されていない原始的な特徴が示されており,軟骨状のアイストークのための開口が含まれています.
- この発見は,Psarolepisのような似たような年齢の化石に決定的な対照性を提供し,対照的な解剖学的特徴を強調しています.
結論:
- 新しい化石のブレインケースは,オステイチアンの初期の進化に関するユニークな洞察を提供します.
- この標本の異常な解剖学は,初期の脊椎動物の進化に関する以前の理解に挑戦しています.
- この発見は,現代の骨魚群の主要な放射線に先立つ解剖学的条件の再構築に大きく貢献しています.
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