一只来自中国西南部的三叠纪晚期的祖先乌
Chun Li1, Xiao-Chun Wu, Olivier Rieppel
1Laboratory of Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of SciencesPO Box 643, Beijing 100044, China. lichun@ivpp.ac.cn
Nature
|November 28, 2008
概括
来自中国的新发现的化石海揭示了关于海外演变的关键见解. 这种古老的爬行动物显示了一个中间阶段,具有发达的石膏,但原始的,澄清了贝的起源.
科学领域:
- 古生物学的古生物学
- 进化生物学 进化生物学
- 脊椎动物解剖学 脊椎动物解剖学
背景情况:
- 乌体图的进化起源是爬行动物进化中的一个重要题,这是由于乌的高度衍生解剖学.
- 已知最古老的乌,Proganochelys,拥有完整的外,没有提供关于其进化开始的线索.
研究的目的:
- 描述一个新的,特别保存的来自中国的化石乌,早于Proganochelys.
- 阐明海外和相关骨结构进化的中间步骤.
主要方法:
- 从中国2200万年前的海洋沉积物中,考古学挖掘和分析了一种新的化石海物种.
- 遗传学分析以确定新物种相对于其他海的进化地位.
主要成果:
- 描述了一种具有完全发育的腹部胎盘,但仅由神经板组成的背的新鱼物种.
- 在新物种中,有扩张的背脊肋骨和缺少骨质皮的证据.
- 遗传学分析将这种新物种定位为已知所有化石和现存的海的基底物种.
结论:
- 这些发现表明,塑在甲之前已经进化了.
- 甲形成的初始阶段涉及神经板的骨化和肋骨扩张,反映了现代海的早期胚胎发育.
- 这一发现驳斥了海外起源于合的骨皮动物的假设,并表明了不同的进化途径.
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