クレータ紀末の絶滅後の胎盤哺乳類の脳より前には筋肉がある
Ornella C Bertrand1, Sarah L Shelley1,2, Thomas E Williamson3
1School of GeoSciences, University of Edinburgh, Grant Institute, Edinburgh, Scotland EH9 3FE, UK.
Science (New York, N.Y.)
|March 31, 2022
まとめ
初期の胎盤哺乳類は最初は体量に比べて脳のサイズが小さかった. 後に 生態学的な競争と ニッチ飽和によって 複数の系統が独立して より大きな脳を進化させたのです
科学分野:
- 古生物学
- 進化生物学
- 比較神経解剖学
背景:
- 哺乳類は高度な脳形成を示し,胎盤哺乳類は特に脳と新皮質の拡大を示している.
- 拡張した哺乳類の新皮質の進化的起源と体の大きさとの関係は不明である.
研究 の 目的:
- 早期の胎盤哺乳類の脳の進化の軌道を調査する
- 哺乳類の進化における 感覚領域の拡大と脳全体の大きさの要因を理解する
主な方法:
- 新しく発見されたパレオセンの化石哺乳類のコンピュータートモグラフィ (CT) スキャン.
- 進化の過程で相対的な脳サイズと体量の変化の分析
- 異なる胎児哺乳類の系統における脳進化の比較分析
主要な成果:
- 以前の仮定とは対照的に,胎盤哺乳類は,より速い体量増加のために相対的な脳サイズが減少しました.
- エオセンの間には 胎盤哺乳類の複数の独立した系統が 大きく大きな脳を進化させた.
- この脳形成は 感覚処理領域の 顕著な成長で特徴づけられました
結論:
- 最初の胎盤放射線は 絶滅後の空いた生態的ニッチを埋めるために 体の大きさを優先しました
- 生態系が飽和し 種間の競争が激化するにつれて 脳の大きさの拡大は 特に感覚領域では 後になって起こりました
- この研究は 哺乳類の脳進化の理解を 洗練しつつあり 体の大きさや 生態学的圧力や 認知の発達との ダイナミックな相互作用を 強調しています
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