原始的な魚は,深いオステイチアンの系統形成に起因する重要なキャラクターを提供します
1Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, PO Box 643, Beijing 100044, China. zhumin@ivpp.ac.cn
Nature
|May 5, 2006
まとめ
新しい魚の化石であるMeemannia eosは,骨のある脊椎動物が独自の皮膚の甲板をどのように進化させたかを明らかにしています. この発見は,主要な魚の系統間の形態学的ギャップを埋め,初期の脊椎動物の進化の洞察を提供しています.
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
- 脊椎動物学 脊椎動物学
背景:
- 骨性脊椎動物 (Osteichthyans) には,アクチノプテリジアン (actinopterygians) とサルコプテリジアン (sarcopterygians) が含まれる.
- サルコプテリジアンの皮の甲羅 (コスミン) の進化的起源は,未だに十分に理解されていない.
- ベースアクトノプテリジアンとサルコプテリジアンには,重要な形態学的ギャップが存在します.
研究 の 目的:
- 新しい化石の魚を記述するために,Meemannia eos gen. et sp. nov., 下デボニアンから.
- コスマインの進化的起源とその構成要素 (毛孔-運河ネットワーク,オドントード,エナメル) を調査する.
- オステイチアンの深い系統と共通の祖先の形態型についての洞察を提供するために.
主な方法:
- 中国ユナン州の化石標本の記述.
- 基礎アクチノプテリジアンとサルコプテリジアンとのメメマニアエオスの比較形態学的分析.
- Meemannia eosがOsteichthyes内の位置を決定するための系統遺伝分析.
主要な成果:
- Meemannia eosは,アクティノプテリジアン型の頭蓋骨の屋根とコスミン型の皮膚表面を持っています.
- 皮膚表面は,多孔運河ネットワークを重ね合わせたオドントードとエナメル層と組み合わせています.
- この4億5000万年前の化石は,コスマインの特徴の段階的な獲得を示しています.
結論:
- サルコプテリジアンにおけるコスミンは,毛穴・運河ネットワークの形成と,その後のオドントード/エナメルの再吸収を含む,漸進的に進化した.
- ミエマニアは,深層の骨イチチアン系を理解するために重要なキャラクターを提供します.
- この発見は,アクチノプテリジアンとサルコプテリジアンの共通の祖先の潜在的な形態型を示唆しています.
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