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Updated: Feb 2, 2026

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Measuring Left Ventricular Pressure in Late Embryonic and Neonatal Mice
Published on: February 23, 2012
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象の大きさのトライアスのシナプシドで,足も直立している
Tomasz Sulej1, Grzegorz Niedźwiedzki2
1Institute of Paleobiology, Polish Academy of Sciences (PAS), Twarda 51/55, 00-818 Warsaw, Poland.
まとめ
トライアス紀後期に生息していた 巨大ダイキノドント (Lisowicia bojani) は 9トンに達し トライアス紀の大草食動物進化に関する以前の考えに 異議を唱えました この発見は 初期の哺乳類の親類が 以前は恐竜に限ると考えられていた 巨大なサイズに達したことを示しています
科学分野:
- 古生物学
- 脊椎動物の進化
- 中世生態系
背景:
- ディキノドントはトライアス時代に流行した多様なシナプシド群である.
- 恐竜だけが トライアス紀後期に 巨大な地上の草食動物体型に達したと考えられていました
- トライアス紀における非恐竜の陸上四足類の上限は,大型恐竜のそれより著しく小さいと考えられていた.
研究 の 目的:
- リソヴィシア・ボジャニという 発見された巨大なダシノドントについてです
- Lisowicia bojaniのサイズと成長パターンの古生物学と進化の影響を分析する.
- トライアスの大草食生物の放射線におけるシナプシド,特に幹群哺乳類の役割を再評価する.
主な方法:
- リソウィシア・ボジャニの化石の記述と骨質学的分析
- 化石の残骸に基づいて体のサイズ (長さ,高さ,質量) を推定する.
- 肢骨の皮質の組織学的検査と,成長速度を推論するための成長停止線 (LAG) の分析.
主要な成果:
- Lisowicia bojaniは巨大なシナプシドとして記述されており,長さ4.5メートル,高さ2.6メートルに達すると推定されています.
- トライアス紀に生息していた最も若いディサイノドントと最大の地上の四足動物である.
- 証拠によると 恐竜や哺乳類に似た 恒久的な急速な成長が示され,LAGの欠如と高度に改造された骨皮質が示されている.
結論:
- リソビシア・ボジャニの発見は トライアス紀で恐竜だけが 巨大草食動物になったという説を覆しました
- 幹群哺乳類 (ディキノドント) は,エオセーンまで哺乳類の進化で再び見られなかった体サイズに達することができたことを示しています.
- この発見はトライアスの大草食生物の多様性と シナプシドの進化能力の理解を大きく広げています
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