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已知最古老的欧特里亚哺乳动物.
Qiang Ji1, Zhe-Xi Luo, Chong-Xi Yuan
1Chinese Academy of Geological Sciences, Beijing 100037, China.
Nature
|April 27, 2002
概括
来自中国的1.25亿年前的乳腺 (胎盘) 哺乳动物化石揭示了早期哺乳动物的多样性. 这种古老的eutherian化石显示了爬适应性,这表明早期胎盘哺乳动物的运动方式有所不同.
科学领域:
- 古生物学的古生物学
- 脊椎动物古生物学 脊椎动物古生物学
- 哺乳动物学 哺乳动物学
背景情况:
- 早期乳头 (胎盘) 哺乳动物的化石记录稀少,特别是在白纪早期.
- 了解类动物的早期进化和多样化对于重建哺乳动物进化史至关重要.
研究的目的:
- 为了描述一个新发现的来自中国下白纪溪形成的eutherian哺乳动物化石.
- 为了确定这个新化石的遗传位置和运动适应性.
- 推断早期eutherian多样化和生态利基区分的含义.
主要方法:
- 化石的挖掘和准备.
- 骨特征的比较解剖学分析,特别是四肢和脚的形态.
- 遗传学分析以确定进化关系.
主要成果:
- 发现一个几乎完整的eutherian骨架约为1.25亿年前.
- 这种化石代表了最古老的eutherian标本之一,具有头骨和骨架.
- 遗传学分析将这种新型的eutherian置于eutherian树的根部.
- 独特的四肢和脚部特征表明了扫描 (爬) 和树木 (树木生活) 适应.
- 这与其他已知的白纪eutherians的陆地或cursorial (运行) 适应形成鲜明对比.
结论:
- 这一发现将化石eutherians与保存的骨的记录推迟了4千万到5千万年.
- 它表明,比先前估计的更为多样化和早期的干部eutherians辐射,先于现存的胎盘超级序列的分子分歧估计.
- 早期的eutherian血统表现出多样化的运动专业化,使得在白纪期间能够适应各种生态.
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