一个白时期的对称形类动物,有一些类似单体的脑后特征
1Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China.
Nature
|January 13, 2006
概括
来自中国的新发现的哺乳动物化石与单极动物有惊人的相似之处,挑战了我们对早期哺乳动物进化和分散的理解. 这一发现揭示了早期白纪时期的spalacotheroid symmetrodonts的进化历史.
科学领域:
- 古生物学的古生物学
- 脊椎动物动物学 脊椎动物动物学
- 进化生物学 进化生物学
背景情况:
- 斯帕拉科状对称龙是现代类动物 (类动物和胎盘动物) 的已灭绝的亲属.
- 这些哺乳动物具有特有的骨特征.
- 之前的理解表明,斯帕拉科泰罗伊德和单极体之间存在明显的分歧.
研究的目的:
- 为了描述来自中国宜形成的一种新型的spalacotheriid哺乳动物化石.
- 为了调查这个新分类中的不寻常的骨特征.
- 分析这一发现对早期哺乳动物进化的进化和生物地理影响.
主要方法:
- 发现化石并准备一个完整的头骨后部和部分头骨.
- 对骨特征的比较解剖学分析,特别是脊椎,骨盆和后肢.
- 遗传学分析结合了新的分类,以推断进化关系.
主要成果:
- 一种新的spalacotheriid哺乳动物在腰椎,骨盆和后肢中表现出与单体动物融合的特征.
- 这些趋同可能代表运动的功能适应或进化发育同位素 (例如,腰椎肋骨的存在/缺失).
- 分析表明,spalacotheroids起源于欧亚大陆,并在白纪早期分散到北美.
结论:
- 这种新化石突出了斯帕拉科泰罗伊德和单体动物之间意外的进化趋同.
- 这一发现完善了我们对类动物进化和哺乳动物早期多样化的理解.
- 这些发现支持了早期白时期哺乳动物生物地理现有模型,特别是欧亚-北美分散模式.
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