歯との発達は,最古ののある脊椎動物でもあった
Martin Rücklin1, Philip C J Donoghue, Zerina Johanson
1School of Earth Sciences, University of Bristol, Wills Memorial Building, Queen's Road, Bristol BS8 1RJ, UK. m.ruecklin@bristol.ac.uk
Nature
|October 19, 2012
まとめ
初期ののある脊椎動物,プラコダームは,歯のような構造ではなく,真の連続歯を持っていた. この発見は,脊椎動物の歯との進化的起源を明らかにしている.
科学分野:
- パレオントロジー・パレオントロジー
- 進化的発達生物学 進化的発達生物学
- 脊椎動物の古生物学について
背景:
- と歯は,脊椎動物の進化における重要な革新であり,適応放射線の中心である.
- 歯の進化的起源と,絶滅したプラコダームにおける歯の存在は,依然として議論の余地がある.
- コンドリキシアンとオステイキシアンの絶滅した姉妹群であるプラコドームにはがあったが,その歯の構造は論争の的だ.
研究 の 目的:
- 絶滅したプラコデルマであるコンパゴピシス・クロッシェリ (Compagopiscis croucheri) の歯の存在と歯の性質を調査する.
- 初期ののある脊椎動物における歯との進化的起源を明らかにする.
- プラコデルマの歯の構造が真の歯または収束進化を表しているかどうかを判断する.
主な方法:
- シンクロトロン放射線X線トモグラフィー顕微鏡 (SRXTM) を利用した.
- コンパゴプシシス・クロッシェリ (Compagopiscis croucheri) の種を分析した.
- 検査されたと歯の発達,構造,および組成.
主要な成果:
- プラコダームのには,明確な軟骨,骨化,皮膚の要素が含まれています.
- コンパゴピシスの歯骨格化は,連続した歯の複合構造である.
- これらの歯は,パルプの空洞を持つ歯骨と骨で構成され,他のプラコダーマ構造とは異なる.
結論:
- コンパゴピシス (Compagopiscis) と他のアルトロダイア (Arthrodires) は,歯のような構造ではなく,真の歯を持っていた.
- 連続歯は,の起源の直後に,グナトストーム系統の初期に進化した.
- プラコダームの歯との発達は統合されず,異なる進化的起源を反映しています.
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