モンゴルの白亜紀末期のエウテリアン哺乳類のエピプビック骨
M J Novacek1, G W Rougier, J R Wible
1Department of Vertebrate Paleontology, American Museum of Natural History, New York, New York 10024, USA. novacek@amnh.org
Nature
|October 23, 1997
まとめ
2つの古代の胎盤哺乳類 (エウテリアン) の系統でエピプビック骨の発見は,これらの哺乳類はこれまで考えられていたよりも原始的であったことを示唆しています. この発見は,現代の胎盤生殖の進化のタイムラインに挑戦しています.
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
- 比較解剖学 比較解剖学とは
背景:
- エピプビック骨は,メソゾーイク期の哺乳類,有袋類,モノトリーム類に見られる骨盤帯の要素であるが,現代の胎盤哺乳類 (エウテリアン類) には存在しない.
- 彼らの機能は議論され,袋のサポートから移動とリターサスペンションまでの理論があります.
研究 の 目的:
- モンゴルの白亜紀後期からの新しいエウテリアン哺乳類を記述する.
- 2つの異なったエウテリアン系統のエピプビック骨の最初の証拠を報告するために.
- これらのエウテリアの系統的位置と哺乳類の進化への影響について調査する.
主な方法:
- 化石発掘と新しいエウテリアン種の記述.
- 骨盤構造に焦点を当てた化石標本の比較解剖学的分析.
- 新種の分類の進化的関係を決定するための系統遺伝分析.
主要な成果:
- モンゴルの白亜紀後期における新しいエウテリアン哺乳類の記述.
- 2つの異なる白亜紀のエウテリアン系におけるエピプビック骨の識別.
- これらの発見は,これらのエウテリア群がエウテリア内での基礎位置にあることを示唆している.
結論:
- これらの白亜紀のエウテリアン類の骨の存在は,この原始的な特徴が,これまで考えられていたよりも長く存在していたことを示しています.
- エウテリアン類のエピプビック骨の喪失は,妊娠期間延長と幼虫の内部の発達と関連している可能性が高い.
- これらの発見は,現代の胎盤哺乳類の重要な生殖戦略が,エウテリアの歴史の後に進化したことを示唆しています.
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