来自北美早期白时期的tribosphenic哺乳动物
1Oklahoma Museum of Natural History and Department of Zoology, University of Oklahoma, Norman, Oklahoma 73019, USA.
Nature
|July 25, 2006
概括
来自北美的一种新的早期白纪哺乳动物化石表明,eutherians (胎盘哺乳动物) 比以前认为的更广泛. 这一发现挑战了关于早期哺乳动物进化和生物地理学的现有理论.
科学领域:
- 古生物学的古生物学
- 哺乳动物学 哺乳动物学
- 进化生物学 进化生物学
背景情况:
- marsupials 和 eutherians (胎盘哺乳动物) 的分歧发生在白纪早期,但它们的早期进化历史和地理分布仍然不清楚.
- 以前的牙科证据表明,eutherian起源于亚洲,后来扩散到北美,那里的有袋动物已经在多样化.
研究的目的:
- 为了描述北美早期白时期的一种新的tribosphenic哺乳动物化石.
- 调查这个新分类对了解早期eutherian生物地理和进化的影响.
主要方法:
- 一个新的哺乳动物分类的描述,基于一个几乎完整的化石标本.
- 形态测量分析和牙特征的特征比较,特别是骨结构.
- 基于形态特征的族系学解释.
主要成果:
- 描述了北美早期白时期的一种新的tribosphenic哺乳动物,它表现出以前只与Eutheria相关的特征.
- 形态测量分析显示了原始的牙结构,警告不要仅基于单独的牙进行解释.
- 这种新的哺乳动物与已知最古老的亚洲Eutheria同时代.
结论:
- 这一发现表明,Eutheria在白纪早期的分布可能比以前所认为的更广泛.
- 在北美早期存在的Eutheria为大陆的晚白纪哺乳动物辐射提供了潜在的解释.
- 这一发现强调了完整标本对于古生物学中精确的遗传学解释的重要性.
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