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シンモリフォームのコンドリキシアン脳内とキメロイド魚の起源
Michael I Coates1, Robert W Gess2, John A Finarelli3,4
1Department of Organismal Biology and Anatomy, University of Chicago, Chicago, Illinois 60637-1508, USA.
Nature
|January 5, 2017
まとめ
ドイカセラクスの化石は シンモライドサメの初期のキメロイドの特徴を示しています この発見は,デボニアン絶滅後の状脊椎動物の進化とコンドリキシアの起源の理解を形づくっている.
科学分野:
- 古生物学
- 進化生物学
- 比較解剖学
背景:
- キメロイド魚 (Holocephali) は,独特の解剖学を持つを持つ脊椎動物の主要なグループです.
- 初期のキメロイドの進化に関する化石の証拠は,既知の化石の初期の専門化により限られている.
- チンマエロイドはコンドリクシアンとグナトストームの祖先の状況に洞察を与えます
研究 の 目的:
- コンピュータトモグラフィーを用いて 謎のコンドリッチアン・ドワイカセラクスの脳を分析する
- チンパンジーの進化の起源と 初期の専門性を調べるため
- 初期のグナトストームとコンドリクシアンの 絶滅への反応を明らかにする.
主な方法:
- コンピュータートモグラフィー (CT) によるドイカセラクスの脳内分析
- 内部と外部の特徴の比較形態学的分析
- 新しいデータを取り入れた 系統遺伝分析
主要な成果:
- およそ2億8千万年前の南アフリカの堆積物から発見されたドイカセラクスの脳は,外見はシンモリド型のサメ,内側はキメロイド型のものである.
- 内部形状は,オティック・ラビリンスと脳空間構成を含む特徴的なキメロイドの特異性を示しています.
- この標本はその種の最も完全な未粉砕の標本で 前例のない細部を提供しています
結論:
- Dwykaselachusはシンモライドとキメロイドの特徴のモザイクを示し,派生キメロイドの頭蓋骨の初期の形態機能的基盤を示唆しています.
- これらの発見は,初期のグナトストームの系統形成と現代のコンドリクシアン起源に堅固な構造を提供している.
- この研究は,デヴォン期の絶滅後のコンドリキシアの適応と生存に光を当てています.
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